View source for Breast milk

{{short description|Milk produced by the mammary glands in the breast of a female human}}
{{redirect|Mother's milk|other uses|Mother's Milk (disambiguation)}}
{{About|human's breast milk|breast milk of other mammals|milk}}
[[Image:Human Breastmilk - Foremilk and Hindmilk.png|thumb|upright=1.6|Two samples of human breast milk. The sample on the left is the first milk produced by the mother, while the sample on the right was produced later during the same breast pumping cycle.]]
'''Breast milk''' (sometimes spelled as '''breastmilk''') or '''mother's milk''' is [[milk]] produced by the [[mammary glands]] in the [[breasts]] of women. Breast milk is the primary source of nutrition for newborn [[infants]], comprising fats, proteins, carbohydrates, and a varying composition of minerals and vitamins. Breast milk also contains substances that help protect an infant against infection and inflammation, such as [[Human milk microbiome|symbiotic bacteria and other microorganisms]] and [[immunoglobulin A]], whilst also contributing to the healthy development of the infant's [[immune system]] and [[gut microbiome]].<ref>{{Cite web|last=Association|first=Australian Breastfeeding|date=2017-07-03|title=Breastmilk composition|url=https://www.breastfeeding.asn.au/bfinfo/breastmilk-composition|access-date=2021-01-29|website=Australian Breastfeeding Association|archive-date=2021-01-19|archive-url=https://web.archive.org/web/20210119061906/https://www.breastfeeding.asn.au/bfinfo/breastmilk-composition|url-status=live}}</ref>

==Use and methods of consumption==
[[File:Bottles of Pumped Breast Milk.jpg|thumb|Pumped breast milk in bottles]]
[[File:Breastfeeding.png|thumb|Breast feeding latch]]
The [[World Health Organization]] (WHO) and [[UNICEF]] recommend [[Breastfeeding#Duration and exclusivity|exclusive breastfeeding]] with breast milk for the first six months of an infant's life. This period is followed by the incorporation of nutritionally adequate and safe complementary solid foods at six months, a stage when an infant's nutrient and energy requirements start to surpass what breast milk alone can provide. Continuation of breastfeeding is recommended up to two years of age. This guidance is due to the protective benefits of breast milk, which include fewer infections such as diarrhea—a protection not afforded by [[formula milk]].<ref name=":8">{{Cite web |title=Infant and young child feeding |url=https://www.who.int/news-room/fact-sheets/detail/infant-and-young-child-feeding |access-date=2024-03-03 |website=www.who.int |language=en |archive-date=2024-03-12 |archive-url=https://web.archive.org/web/20240312030238/https://www.who.int/News-Room/Fact-Sheets/Detail/Infant-and-Young-Child-Feeding |url-status=live }}</ref>

Breast milk constitutes the sole source of nutrition for exclusively breastfed newborns, supplying all necessary nutrients for infants up to six months. Beyond this age, breast milk continues to be a source of energy for children up to two years old, providing over half of a child's energy needs up to the age of one and a third of the needs between one and two years of age.<ref name=":8" />

Despite the capability of most newborns to latch onto the mother's breast within an hour of birth, globally, sixty percent of infants are not breastfed within this crucial first hour. Breastfeeding within the first hour of life protects the newborn from acquiring infections and reduces risk of death during the neonatal period.<ref name="who1">{{cite web |date=2021 |title=World Health Organization; Exclusive breastfeeding |url=https://www.who.int/nutrition/topics/exclusive_breastfeeding/en/ |access-date=2021-12-01 |publisher=Who.int |archive-date=2019-10-30 |archive-url=https://web.archive.org/web/20191030175834/https://www.who.int/nutrition/topics/exclusive_breastfeeding/en/ |url-status=live }}</ref><ref>{{cite journal |last1=Eidelman |first1=Arthur I. |last2=Schanler |first2=Richard J. |last3=Johnston |first3=Margreete |last4=Landers |first4=Susan |last5=Noble |first5=Larry |last6=Szucs |first6=Kinga |last7=Viehmann |first7=Laura |title=Breastfeeding and the Use of Human Milk |journal=Pediatrics |date=March 2012 |volume=129 |issue=3 |pages=e827–e841 |doi=10.1542/peds.2011-3552 |pmid=22371471 |doi-access=free }}</ref>

Alternatively, breast milk can be expressed using a [[breast pump]] and administered via [[baby bottle]], cup, spoon, supplementation drip system, or [[nasogastric tube]].<ref name=":6">{{cite journal |last1=Allen |first1=Elizabeth |last2=Rumbold |first2=Alice R |last3=Keir |first3=Amy |last4=Collins |first4=Carmel T |last5=Gillis |first5=Jennifer |last6=Suganuma |first6=Hiroki |title=Avoidance of bottles during the establishment of breastfeeds in preterm infants |journal=Cochrane Database of Systematic Reviews |date=21 October 2021 |volume=2021 |issue=10 |article-number=CD005252 |doi=10.1002/14651858.CD005252.pub5 |pmid=34671969 |pmc=8529385 }}</ref> This method is especially beneficial for [[preterm babies]] who may initially lack the ability to suck effectively. Using cups to feed expressed breast milk and other supplements results in improved breastfeeding outcomes in terms of both duration and extent, compared with traditional bottle and tube feeding.<ref name=":6" /><ref>{{cite journal |last1=Abouelfettoh |first1=Amel M |last2=Dowling |first2=Donna A |last3=Dabash |first3=Soheir A |last4=Elguindy |first4=Shadia R |last5=Seoud |first5=Iman A |title=Cup versus bottle feeding for hospitalized late preterm infants in Egypt: A quasi-experimental study |journal=International Breastfeeding Journal |date=2008 |volume=3 |issue=1 |page=27 |doi=10.1186/1746-4358-3-27 |pmid=19025602 |pmc=2635351 |doi-access=free}}</ref>

For mothers unable to produce an adequate supply of breast milk, the use of [[pasteurized]] donor human breast milk is a viable option. In the absence of pasteurized donor milk, commercial formula milk is recommended as a secondary alternative.<ref name=":7">{{cite journal |last1=Pound |first1=Catherine |last2=Unger |first2=Sharon |last3=Blair |first3=Becky |title=Pasteurized and unpasteurized donor human milk |journal=Paediatrics & Child Health |date=16 December 2020 |volume=25 |issue=8 |pages=549–550 |doi=10.1093/pch/pxaa118 |pmid=33365109 |pmc=7739531 }}</ref> However, unpasteurized breast milk from a source other than the infant's mother, particularly when shared informally, carries the risk of [[Vertical transmission|vertically transmitting]] bacteria, viruses (such as [[HIV]]), and other microorganisms from the donor to the infant, rendering it an unsafe alternative.<ref name=":7" /><ref>{{Cite web |last=Society |first=Canadian Paediatric |title=Pasteurized and unpasteurized donor human milk {{!}} Canadian Paediatric Society |url=https://cps.ca/en/documents//position//pasteurized-and-unpasteurized-donor-human-milk/ |access-date=2022-04-28 |website=cps.ca |language=en |archive-date=2021-04-23 |archive-url=https://web.archive.org/web/20210423020155/https://www.cps.ca/en/documents/position/pasteurized-and-unpasteurized-donor-human-milk |url-status=live }}</ref>

==Benefits==<!-- DISTINGUISH: Between benefits of 'breast milk' and 'breastfeeding' -->

Breastfeeding offers health benefits to mother and child even after infancy.<ref>{{cite web|url=https://www.who.int/nutrition/topics/infantfeeding_recommendation/en/
|archive-url=https://web.archive.org/web/20120108021950/http://www.who.int/nutrition/topics/infantfeeding_recommendation/en/
|archive-date=January 8, 2012
|title=The World Health Organization's infant feeding recommendation
}}</ref> These benefits include proper heat production and adipose tissue development,<ref>{{cite journal | vauthors = Yu H, Dilbaz S, Coßmann J, Hoang AC, Diedrich V, Herwig A, Harauma A, Hoshi Y, Moriguchi T, Landgraf K, Körner A, Lucas C, Brodesser S, Balogh L, Thuróczy J, Karemore G, Kuefner MS, Park EA, Rapp C, Travers JB, Röszer T | display-authors = 6 | title = Breast milk alkylglycerols sustain beige adipocytes through adipose tissue macrophages | journal = The Journal of Clinical Investigation | volume = 129 | issue = 6 | pages = 2485–2499 | date = May 2019 | pmid = 31081799 | pmc = 6546455 | doi = 10.1172/JCI125646 }}</ref> a 73% decreased risk of [[sudden infant death syndrome]],<ref>{{cite journal | vauthors = Hauck FR, Thompson JM, Tanabe KO, Moon RY, Vennemann MM | title = Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis | journal = Pediatrics | volume = 128 | issue = 1 | pages = 103–10 | date = July 2011 | pmid = 21669892 | doi = 10.1542/peds.2010-3000 | s2cid = 1257376 }}</ref> increased [[intelligence]],<ref>{{Cite web |url=https://www.sciencedaily.com/releases/2008/05/080505162902.htm |title=Breastfeeding Associated With Increased Intelligence, Study Suggests<!-- Bot generated title --> |access-date=2018-02-28 |archive-date=2021-01-15 |archive-url=https://web.archive.org/web/20210115014247/https://www.sciencedaily.com/releases/2008/05/080505162902.htm |url-status=live }}</ref> decreased likelihood of contracting [[middle ear infections]],<ref>{{cite journal | vauthors = Persico M, Podoshin L, Fradis M, Golan D, Wellisch G | title = Recurrent middle-ear infections in infants: the protective role of maternal breast feeding | journal = Ear, Nose, & Throat Journal | volume = 62 | issue = 6 | pages = 297–304 | date = June 1983 | pmid = 6409579 }}</ref> cold and [[flu]] resistance,<ref>{{cite journal | vauthors = Cantey JB, Bascik SL, Heyne NG, Gonzalez JR, Jackson GL, Rogers VL, Sheffield JS, Treviño S, Sendelbach D, Wendel GD, Sánchez PJ | display-authors = 6 | title = Prevention of mother-to-infant transmission of influenza during the postpartum period | journal = American Journal of Perinatology | volume = 30 | issue = 3 | pages = 233–40 | date = March 2013 | pmid = 22926635 | doi = 10.1055/s-0032-1323585 | s2cid = 37717003 }}</ref> a tiny decrease in the risk of [[childhood leukemia]],<ref>{{cite journal | vauthors = Aguiar H, Silva AI | title = [Breastfeeding: the importance of intervening] | journal = Acta Médica Portuguesa | volume = 24 | pages = 889–96 | date = December 2011 | issue = Suppl 4 | pmid = 22863497 }}</ref> lower risk of childhood onset [[diabetes]],<ref>{{cite journal | vauthors = Finigan V | title = Breastfeeding and diabetes: Part 2 | journal = The Practising Midwife | volume = 15 | issue = 11 | pages = 33–4, 36 | date = December 2012 | pmid = 23304866 }}</ref> decreased risk of [[asthma]] and [[eczema]],<ref name="pmid23372130">{{cite journal | vauthors = Salone LR, Vann WF, Dee DL | title = Breastfeeding: an overview of oral and general health benefits | journal = Journal of the American Dental Association | volume = 144 | issue = 2 | pages = 143–51 | date = February 2013 | pmid = 23372130 | doi = 10.14219/jada.archive.2013.0093 | doi-access = free }}</ref> decreased [[dental problems]],<ref name="pmid23372130"/> decreased risk of [[obesity]] later in life,<ref>{{cite journal | vauthors = Lausten-Thomsen U, Bille DS, Nässlund I, Folskov L, Larsen T, Holm JC | title = Neonatal anthropometrics and correlation to childhood obesity--data from the Danish Children's Obesity Clinic | journal = European Journal of Pediatrics | volume = 172 | issue = 6 | pages = 747–51 | date = June 2013 | pmid = 23371390 | doi = 10.1007/s00431-013-1949-z | s2cid = 25934526 }}</ref> and a decreased risk of developing [[psychological disorders]], including in [[adoption|adopted]] children.<ref>{{cite journal | vauthors = Gribble KD | title = Mental health, attachment and breastfeeding: implications for adopted children and their mothers | journal = International Breastfeeding Journal | volume = 1 | issue = 1 | article-number = 5 | date = March 2006 | pmid = 16722597 | pmc = 1459116 | doi = 10.1186/1746-4358-1-5 | doi-access = free }}</ref> In addition, feeding an infant breast milk is associated with lower insulin levels and higher leptin levels compared feeding an infant via [[Infant formula|powdered-formula]].<ref name="Crume_2011">{{cite journal | vauthors = Crume TL, Ogden L, Maligie M, Sheffield S, Bischoff KJ, McDuffie R, Daniels S, Hamman RF, Norris JM, Dabelea D | display-authors = 6 | title = Long-term impact of neonatal breastfeeding on childhood adiposity and fat distribution among children exposed to diabetes in utero | journal = Diabetes Care | volume = 34 | issue = 3 | pages = 641–5 | date = March 2011 | pmid = 21357361 | pmc = 3041197 | doi = 10.2337/dc10-1716 }}</ref> Many of the infection-fighting and immune system related benefits are associated with [[human milk oligosaccharide]]s.<ref>{{cite journal |last1=Bode |first1=L. |title=Human milk oligosaccharides: Every baby needs a sugar mama |journal=Glycobiology |date=September 2012 |volume=22 |issue=9 |pages=1147–1162 |doi=10.1093/glycob/cws074 |pmid=22513036 |pmc=3406618 }}</ref>

Breastfeeding also provides health benefits for the mother. It assists the uterus in returning to its pre-pregnancy size and reduces post-partum bleeding, through the production of oxytocin (see Production). Breastfeeding can also reduce the risk of [[breast cancer]] later in life.<ref>{{cite web | title = Breast-Feeding Might Cut Risk for Tough-to-Treat Breast Cancer: Study | url = http://www.womenshealth.gov/news/headlines/669591.cfm | access-date = 18 October 2012 | first1 = Alyssa | last1 = Gillego | first2 = Stephanie | last2 = Bernik | name-list-style = vanc | archive-date = 3 March 2016 | archive-url = https://web.archive.org/web/20160303173034/http://www.womenshealth.gov/news/headlines/669591.cfm }}</ref><ref>{{cite journal|last=Levin|first=Roy J. | name-list-style = vanc |title=The breast/nipple/areola complex and human sexuality|journal=Sexual & Relationship Therapy|date=May 2006|volume=21|issue=2|pages=237–249|doi=10.1080/14681990600674674|s2cid=219696836 }}</ref> [[Lactation]] may also reduce the risk for both mother and infant from both types of diabetes.<ref>{{cite journal | vauthors = Gouveri E, Papanas N, Hatzitolios AI, Maltezos E | title = Breastfeeding and diabetes | journal = Current Diabetes Reviews | volume = 7 | issue = 2 | pages = 135–42 | date = March 2011 | pmid = 21348815 | doi = 10.2174/157339911794940684 }}</ref> Lactation may protect the infant from specifically developing Type 2 diabetes, as studies have shown that bioactive ingredients in human breast milk could prevent excess weight gain during childhood via contributing to a feeling of energy and satiety. The lower risk of child-onset diabetes may be more applicable to infants who were born from diabetic mothers.<ref name="Crume_2011" /> The reason is that while breastfeeding for at least the first six months of life minimizes the risk of type 1 diabetes from occurring in the infant, inadequate breastfeeding in an infant prenatally exposed to diabetes was associated with a higher risk of the child developing diabetes later.<ref name="Crume_2011" /> There are arguments that breastfeeding may contribute to protective effects against the development of type 1 diabetes because the alternative of bottle-feeding may expose infants to unhygienic feeding conditions.<ref>{{cite journal | vauthors = Taylor JS, Kacmar JE, Nothnagle M, Lawrence RA | title = A systematic review of the literature associating breastfeeding with type 2 diabetes and gestational diabetes | journal = Journal of the American College of Nutrition | volume = 24 | issue = 5 | pages = 320–6 | date = October 2005 | pmid = 16192255 | doi = 10.1080/07315724.2005.10719480 | s2cid = 24794632 }}</ref>

Though it is almost universally prescribed, in some countries during the 1950s, the practice of [[breastfeeding]] went through a period where it was out of vogue and the use of [[infant formula]] was considered superior to breast milk.<ref>{{Cite web |title=Breastfeeding |url=https://www.who.int/health-topics/breastfeeding |access-date=2022-04-28 |website=www.who.int |language=en |archive-date=2019-05-29 |archive-url=https://web.archive.org/web/20190529191644/https://www.who.int/nutrition/topics/exclusive_breastfeeding/en/ |url-status=live }}</ref> However, it is since universally recognized that there is no commercial formula that can adequately substitute for breast milk. In addition to the appropriate amounts of [[carbohydrate]], [[protein]], and [[fat]], breast milk provides [[vitamin]]s, [[Mineral (nutrient)|minerals]], [[digestive enzyme]]s,<ref name="pmid21091243">{{cite journal | vauthors = Chantry CJ, Wiedeman J, Buehring G, Peerson JM, Hayfron K, K'Aluoch O, Lonnerdal B, Israel-Ballard K, Coutsoudis A, Abrams B | title = Effect of flash-heat treatment on antimicrobial activity of breastmilk | journal = Breastfeeding Medicine | volume = 6 | issue = 3 | pages = 111–6 | date = June 2011 | pmid = 21091243 | pmc = 3143386 | doi = 10.1089/bfm.2010.0078 }}</ref> and [[hormones]].<ref name="pmid21091243"/> Breast milk also contains antibodies and lymphocytes from the mother that may help the baby resist infections.<ref>{{cite journal | vauthors = Bertotto A, Castellucci G, Fabietti G, Scalise F, Vaccaro R | title = Lymphocytes bearing the T cell receptor gamma delta in human breast milk | journal = Archives of Disease in Childhood | volume = 65 | issue = 11 | pages = 1274–5 | date = November 1990 | pmid = 2147370 | pmc = 1792611 | doi = 10.1136/adc.65.11.1274-a }}</ref> The immune function of breast milk is individualized, as the mother, through her touching and taking care of the baby, comes into contact with pathogens that colonize the baby, and, as a consequence, her body makes the appropriate antibodies and immune cells.<ref>{{Cite web |url=http://www.gentlebirth.org/vre/newimmun.html |title=The Newborn Immune System and Immunological Benefits of Breastmilk<!-- Bot generated title --> |access-date=2013-02-23 |archive-date=2021-03-09 |archive-url=https://web.archive.org/web/20210309164329/http://gentlebirth.org/vre/newimmun.html |url-status=live }}</ref>

At around four months of age, the internal iron supplies of the infant, held in the hepatic cells of the liver, are exhausted. The [[American Academy of Pediatrics]] recommends that at this time that an iron supplement should be introduced.<ref>{{cite journal |last1=Baker |first1=Robert D. |last2=Greer |first2=Frank R. |last3=Committee on Nutrition American Academy of |first3=Pediatrics |title=Diagnosis and Prevention of Iron Deficiency and Iron-Deficiency Anemia in Infants and Young Children (0–3 Years of Age) |journal=Pediatrics |date=November 2010 |volume=126 |issue=5 |pages=1040–1050 |doi=10.1542/peds.2010-2576 |pmid=20923825 }}</ref> Other health organisations such as the [[National Health Service|NHS]] in the [[United Kingdom|UK]] have no such recommendation.<ref name=":0">{{Cite web|url=https://www.nhs.uk/start4life/baby/first-foods|title=First Foods|website=Start 4 Life|publisher=[[National Health Service]]|access-date=2018-11-21|archive-date=2018-11-22|archive-url=https://web.archive.org/web/20181122005517/https://www.nhs.uk/start4life/baby/first-foods|url-status=live}}</ref> Breast milk contains less iron than formula, but the iron is more [[bioavailability|bioavailable]] as [[lactoferrin]], which carries more safety for mothers and children than ferrous sulphate.<ref>{{cite journal|vauthors=Paesano R, Pacifici E, Benedetti S, Berlutti F, Frioni A, Polimeni A, Valenti P|date=October 2014|title=Safety and efficacy of lactoferrin versus ferrous sulphate in curing iron deficiency and iron deficiency anaemia in hereditary thrombophilia pregnant women: an interventional study|journal=Biometals|volume=27|issue=5|pages=999–1006|doi=10.1007/s10534-014-9723-x|pmid=24590680|s2cid=14807311}}</ref>

Both the AAP<ref name=":1">{{Cite journal|id={{ProQuest|234313238}}|last=Armstrong|first=Carrie|date=2009-07-15|title=AAP Doubles Recommended Vitamin D Intake in Children|url=https://www.aafp.org/afp/2009/0715/p196.html|journal=American Family Physician|volume=80|issue=2|access-date=2018-11-21|archive-date=2022-03-22|archive-url=https://web.archive.org/web/20220322013412/https://www.aafp.org/afp/2009/0715/p196.html|url-status=live}}</ref> and the NHS recommend [[vitamin D]] supplementation for breastfed infants.<ref name=":0" /> Vitamin D can be synthesised by the infant via exposure to sunlight; however, many infants are deficient due to being kept indoors or living in areas with insufficient sunlight. Formula is supplemented with vitamin D for this reason.<ref name=":0" /><ref name=":1" />

==Production==
{{See also|Low milk supply}}
Under the influence of the hormones [[prolactin]] and [[oxytocin]], women produce milk after [[childbirth]] to feed the [[baby]].<ref>{{Cite web |title=Lactation (Human Milk Production): Causes & How It Works |url=https://my.clevelandclinic.org/health/body/22201-lactation |access-date=2022-04-28 |website=Cleveland Clinic |archive-date=2022-04-28 |archive-url=https://web.archive.org/web/20220428110149/https://my.clevelandclinic.org/health/body/22201-lactation |url-status=live }}</ref> The initial milk produced is referred to as [[colostrum]], which is high in the [[immunoglobulin]] [[IgA]], which coats the [[gastrointestinal tract]]. This helps to protect the newborn until its own [[immune system]] is functioning properly. It also creates a mild laxative effect, expelling [[meconium]] and helping to prevent the build-up of [[bilirubin]] (a contributory factor in [[jaundice]]<ref>{{Cite journal |last1=Srinivasjois |first1=Ravisha |last2=Sharma |first2=Ajay |last3=Shah |first3=Prakesh |last4=Kava |first4=Maina |date=July 2011 |title=Effect of induction of meconium evacuation using per rectal laxatives on neonatal hyperbilirubinemia in term infants: a systematic review of randomized controlled trials |journal=Indian Journal of Medical Sciences |volume=65 |issue=7 |pages=278–285 |doi=10.4103/0019-5359.107388 |doi-broken-date=11 July 2025 |doi-access=free |pmid=23422701 }}</ref>). Male lactation  can occur; the production or administration of the hormone prolactin is necessary to induce lactation (see [[male lactation]]).

Actual inability to produce enough milk is rare, with studies showing that mothers from malnourished regions still produce amounts of milk of similar quality to that of mothers in developed countries.<ref>{{cite book |doi=10.1007/978-1-4615-7207-7_2 |chapter=Cross-Cultural Differences in Lactational Performance |title=Human Lactation 2 |date=1986 |last1=Prentice |first1=Andrew |last2=Paul |first2=Alison |last3=Prentice |first3=Ann |last4=Black |first4=Alison |last5=Cole |first5=Tim |last6=Whitehead |first6=Roger |pages=13–44 |isbn=978-1-4615-7209-1 }}</ref> There are many reasons a mother may [[low milk supply|not produce enough breast milk]].<ref>{{Cite web |title=Low milk supply: What causes it? |url=https://www.mayoclinic.org/healthy-lifestyle/infant-and-toddler-health/expert-answers/low-milk-supply/faq-20058148 |access-date=2022-04-28 |website=Mayo Clinic |language=en |archive-date=2022-04-28 |archive-url=https://web.archive.org/web/20220428110742/https://www.mayoclinic.org/healthy-lifestyle/infant-and-toddler-health/expert-answers/low-milk-supply/faq-20058148 |url-status=live }}</ref> Some of the most common reasons are an improper latch (i.e., the baby does not connect efficiently with the nipple), not nursing or pumping enough to meet supply, certain medications (including estrogen-containing [[hormonal contraceptives]]), illness, and dehydration. A rarer reason is [[Sheehan's syndrome]], also known as postpartum [[hypopituitarism]], which is associated with prolactin deficiency and may require hormone replacement.

The amount of milk produced depends on how often the mother is nursing and/or [[breast pump|pumping]]: the more the mother nurses her baby or pumps, the more milk is produced.<ref name="mayo1">{{cite web |url=http://www.mayoclinic.com/health/breast-feeding/FL00120 |title=Breast-feeding: Pumping and maintaining your milk supply |publisher=MayoClinic.com |date=2010-03-13 |access-date=2011-10-26 |archive-date=2019-08-26 |archive-url=https://web.archive.org/web/20190826135228/http://www.mayoclinic.com/health/breast-feeding/FL00120 |url-status=live }}</ref><ref>{{cite web |url=http://parenting.ivillage.com/newborn/nbreastfeed/0,,456z,00.html |title=Breast milk: Increasing supply – iVillage |publisher=Parenting.ivillage.com |date=2010-01-01 |access-date=2011-10-26 |archive-url=https://web.archive.org/web/20100514140816/http://parenting.ivillage.com/newborn/nbreastfeed/0,,456z,00.html |archive-date=2010-05-14 }}</ref><ref>{{cite web |url=http://www.babies.sutterhealth.org/breastfeeding/bf_production.html |title=How Breast Milk is Produced |publisher=Babies.sutterhealth.org |access-date=2011-10-26 |archive-date=2019-09-16 |archive-url=https://web.archive.org/web/20190916161254/http://www.babies.sutterhealth.org/breastfeeding/bf_production.html |url-status=live }}</ref> It is beneficial to nurse when the baby wants to nurse rather than on a schedule. A [[Cochrane review]] came to the conclusion that a greater volume of milk is expressed whilst listening to relaxing audio during breastfeeding, along with warming and massaging of the breast prior to and during feeding. A greater volume of milk expressed can also be attributed to instances where the mother starts pumping milk sooner, even if the infant is unable to breastfeed.<ref name="BeckerSmith2015">{{cite journal | vauthors = Becker GE, Smith HA, Cooney F | editor1-first = Genevieve E | editor1-last = Becker | title = Methods of milk expression for lactating women | journal = The Cochrane Database of Systematic Reviews | issue = 2 | article-number = CD006170 | date = February 2015 | pmid = 25722103 | doi = 10.1002/14651858.CD006170.pub4 }}</ref>

[[Sodium]] concentration is higher in hand-expressed milk, when compared with the use of manual and electric pumps, and fat content is higher when the breast has been massaged, in conjunction with listening to relaxing audio. This may be important for [[low birthweight]] infants.<ref name="BeckerSmith2015"/> If pumping, it is helpful to have an electric, high-grade pump so that all of the milk ducts are stimulated. [[Galactagogue]]s increase milk supply, although even herbal variants carry risks. Non-pharmaceutical methods should be tried first, such as pumping out the mother's breast milk supply often, warming or massaging the breast, as well as starting milk pumping earlier after the child is born if they cannot drink milk at the breast.<ref name="BeckerSmith2015" /><ref>{{cite web
|url=http://kellymom.com/bf/can-i-breastfeed/herbs/fenugreek/
|title=Fenugreek Seed for Increasing Supply
|access-date=2014-07-15
|archive-date=2021-03-09
|archive-url=https://web.archive.org/web/20210309095456/https://kellymom.com/bf/can-i-breastfeed/herbs/fenugreek/
|url-status=live
}}</ref><ref>{{cite web
|url=http://kellymom.com/bf/got-milk/supply-worries/low-supply/
|title=Increasing Low Milk Supply
|access-date=2014-07-15
|archive-date=2021-01-18
|archive-url=https://web.archive.org/web/20210118103019/https://kellymom.com/bf/got-milk/supply-worries/low-supply/
|url-status=live
}}</ref><ref>{{cite journal |last1=Asztalos |first1=Elizabeth |title=Supporting Mothers of Very Preterm Infants and Breast Milk Production: A Review of the Role of Galactogogues |journal=Nutrients |date=12 May 2018 |volume=10 |issue=5 |page=600 |doi=10.3390/nu10050600 |pmid=29757199 |pmc=5986480 |doi-access=free }}</ref>

== Composition ==
{{Further|Anti inflammatory agents in breast milk|Human milk immunity|Human milk microbiome}}
{{Infobox nutritional value
| name            = Human breast milk
| image_alt       = 
| caption         = 
| serving_size    = 100 {{abbr|mL|milliter}}
| kcal            = 65–78
| carbs           = 6.7–7.8{{nbsp}}g
| starch          = 
| sugars          = 
| lactose         = 6.7–7.8{{nbsp}}g
| fat             = 3.2–4.8{{nbsp}}g
| satfat          = 
| transfat        = 
| monofat         = 
| polyfat         = 
| omega3fat       = 
| omega6fat       = 
| protein         = 0.8–1.4{{nbsp}}g
| tryptophan      = 
| threonine       = 
| isoleucine      = 
| leucine         = 
| lysine          = 
| methionine      = 
| cystine         = 
| phenylalanine   = 
| tyrosine        = 
| valine          = 
| arginine        = 
| histidine       = 
| alanine         = 
| aspartic acid   = 
| glutamic acid   = 
| glycine         = 
| proline         = 
| serine          = 
| hydroxyproline  = 
| water           = 87–88{{nbsp}}g
| cholesterol     = 
| alcohol         = 
| caffeine        = 
| vitA_ug         = 
| vitA_iu         = 220
| betacarotene_ug = 
| lutein_ug       = 
| thiamin_ug      = 21
| riboflavin_ug   = 35
| niacin_mg       = 0.15
| pantothenic_mg  = 
| vitB6_ug        = 9–21
| folate_ug       = 2–5
| vitB12_ug       = 0.1
| choline_mg      = 
| vitC_mg         = 4
| vitD_ug         = 
| vitD_iu         = 2
| vitE_mg         = 0.2
| vitK_ug         = 0.2
| calcium_mg      = 20–25
| copper_mg       = 0.00001–0.00003
| iron_mg         = 0.03–0.07
| magnesium_mg    = 3–3.5
| manganese_mg    = 0.0003–0.0004
| phosphorus_mg   = 12–14
| potassium_mg    = 40–55
| selenium_ug     = 1–2.5
| sodium_mg       = 15–25
| zinc_mg         = 0.0001–0.0003
| opt1n           = 
| opt1v           = 
| note            = 
| source          = <ref name="pmid23178060">{{cite journal| author=Ballard O, Morrow AL| title=Human milk composition: nutrients and bioactive factors. | journal=Pediatr Clin North Am | year= 2013 | volume= 60 | issue= 1 | pages= 49–74 | pmid=23178060 | doi=10.1016/j.pcl.2012.10.002 | pmc=3586783 }}</ref><ref name="pmid32252145">{{cite journal| author=Kim SY, Yi DY| title=Components of human breast milk: from macronutrient to microbiome and microRNA. | journal=Clin Exp Pediatr | year= 2020 | volume= 63 | issue= 8 | pages= 301–309 | pmid=32252145 | doi=10.3345/cep.2020.00059 | pmc=7402982 }}</ref><ref name="pmid11339161">{{cite journal | author=Greer FR | title=Do breastfed infants need supplemental vitamins? | journal=Pediatr Clin North Am | year=2001 | volume=48 | issue=2 | pages=415–23 | pmid=11339161 | doi=10.1016/s0031-3955(08)70034-8 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11339161 | access-date=2024-03-03 | archive-date=2024-07-26 | archive-url=https://web.archive.org/web/20240726181925/https://www.sciencedirect.com/unsupported_browser }}</ref>
| float           = right
}}
<!--{| class = "wikitable" style = "margin: 0 0 1em 1em; float:right"
|+ Composition of human breast milk<ref>[http://archive.unu.edu/unupress/food/8F174e/8F174E04.htm Constituents of human milk] {{Webarchive|url=https://web.archive.org/web/20170910132409/http://archive.unu.edu/unupress/food/8F174e/8F174E04.htm |date=2017-09-10 }} United Nations University Centre</ref>
|colspan=2| '''Fat''' (g/100 ml)
|-
| total
| 4.2
|-
| fatty acids – length 8C
| 
|-
| polyunsaturated fatty acids
| 0.6
|-
| cholesterol
| 0.016
|-
|colspan=2| '''Protein''' (g/100 ml)
|-
| total
| 1.1
|-
| casein
| 0.4
|-
| a-lactalbumin
| 0.3
|-
| lactoferrin (apo-lactoferrin)
| 0.2
|-
| IgA
| 0.1
|-
| IgG
| 0.001
|-
| lysozyme
| 0.05
|-
| serum albumin
| 0.05
|-
| β-lactoglobulin
| –
|-
|colspan=2| '''Carbohydrate''' (g/100 ml)
|-
| lactose
| 7
|-
| oligosaccharides
| 0.5
|-
|colspan=2| '''Minerals''' (g/100 ml)
|-
| calcium
| 0.03
|-
| phosphorus
| 0.014
|-
| sodium
| 0.015
|-
| potassium
| 0.055
|-
| chlorine
| 0.043
|}-->
Breast milk contains fats, proteins, carbohydrates (including lactose and human milk oligosaccharides), and a varying composition of minerals and vitamins.<ref>{{cite journal |last1=Kim |first1=Su Yeong |last2=Yi |first2=Dae Yong |title=Components of human breast milk: from macronutrient to microbiome and microRNA |journal=Clinical and Experimental Pediatrics |date=15 August 2020 |volume=63 |issue=8 |pages=301–309 |doi=10.3345/cep.2020.00059 |pmid=32252145 |pmc=7402982 }}</ref><ref>{{cite book |doi=10.1201/9781482294491-7 |chapter=Biomolecules II: Biologically Important Molecules Other than Carbohydrates, Lipids, Proteins, and Nucleic Acids |title=Plant Cell Biology |date=2010 |pages=89–118 |isbn=978-0-429-08034-0 }}</ref> The composition changes over a single feed as well as over the period of lactation.<ref name="National Center for Biotechnology Information, U.S. National Library of Medicine">{{cite journal | vauthors = Andreas NJ, Kampmann B, Mehring Le-Doare K | title = Human breast milk: A review on its composition and bioactivity | journal = Early Human Development | volume = 91 | issue = 11 | pages = 629–35 | date = November 2015 | pmid = 26375355 | doi = 10.1016/j.earlhumdev.2015.08.013 | hdl = 10044/1/25981 | hdl-access = free }}</ref> Changes are particularly pronounced in [[marsupial]]s.<ref name="Marsupial and monotreme milk – a re">{{cite journal | vauthors =	Stannard HJ, Miller RD, Old JM | title = Marsupial and monotreme milk – a review of its nutrients and immune properties | journal = PeerJ | volume = 8 | article-number = e9335 | date = 2020 | doi = 10.7717/peerj.9335 | pmid = 32612884 | pmc = 7319036 | doi-access = free }}</ref>

[[File:Colostrum vs breastmilk.jpg|thumb|[[Colostrum]] vs breastmilk]]

During the first few days after delivery, the mother produces [[colostrum]]. This is a thin yellowish fluid that is the same fluid that sometimes leaks from the breasts during pregnancy. It is rich in protein and antibodies that provide passive immunity to the baby (the baby's immune system is not fully developed at birth). Colostrum also helps the newborn's digestive system to grow and function properly.{{citation needed|date=November 2023}}

Colostrum will gradually change to become mature milk. In the first 3–4 days it will appear thin and watery and will taste very sweet; later, the milk will be thicker and creamier. Human milk quenches the baby's thirst and hunger and provides the proteins, sugar, minerals, and antibodies that the baby needs.

In the 1980s and 1990s, lactation professionals (De Cleats) used to make a differentiation between foremilk and hindmilk. But this differentiation causes confusion as there are not two types of milk. Instead, as a baby breastfeeds, the fat content very gradually increases, with the milk becoming fattier and fattier over time.<ref>{{cite web|last1=Mohrbacher|first1=Nancy|title=Worries About Foremilk and Hindmilk|url=https://breastfeedingusa.org/content/article/worries-about-foremilk-and-hindmilk|website=Breastfeeding USA|access-date=1 March 2015|date=2011-07-10|archive-date=2021-01-15|archive-url=https://web.archive.org/web/20210115204204/https://breastfeedingusa.org/content/article/worries-about-foremilk-and-hindmilk}}</ref>

The level of [[Immunoglobulin A]] (IgA) in breast milk remains high from day 10 until at least 7.5 months post-partum.<ref>{{cite journal | vauthors = Rechtman DJ, Ferry B, Lee ML, Chapel H |year=2002 |title=Immunoglobulin A (IgA) content of human breast milk over time |journal=International Journal of Infectious Diseases |volume=6 |issue=S3 |pages=S58 |doi= 10.1016/s1201-9712(02)90302-4|doi-access=free }}</ref>

Human milk contains 0.8–0.9% protein, 4.5% fat, 7.1% carbohydrates, and 0.2% ash (minerals).<ref>{{cite book | vauthors = Belitz H | title = Food Chemistry |location=Berlin |publisher=Springer |edition=4th |year=2009 |isbn=978-3-540-69935-4 |page=501 [table 10.5] }}</ref> Carbohydrates are mainly [[lactose]]; several lactose-based oligosaccharides (also called [[human milk oligosaccharide]]s) have been identified as minor components.<ref>{{cite journal |last1=Corona |first1=Laura |last2=Lussu |first2=Anna |last3=Bosco |first3=Alice |last4=Pintus |first4=Roberta |last5=Cesare Marincola |first5=Flaminia |last6=Fanos |first6=Vassilios |last7=Dessì |first7=Angelica |title=Human Milk Oligosaccharides: A Comprehensive Review towards Metabolomics |journal=Children |date=14 September 2021 |volume=8 |issue=9 |page=804 |doi=10.3390/children8090804 |pmid=34572236 |pmc=8465502 |doi-access=free }}</ref> The fat fraction contains specific [[triglycerides]] of [[palmitic acid|palmitic]] and [[oleic acid]] (O-P-O triglycerides), and also lipids with trans bonds (see: [[trans fat]]). The lipids are [[vaccenic acid]], and [[conjugated linoleic acid]] (CLA) accounting for up to 6% of the human milk fat.<ref>{{cite journal | vauthors = Precht D, Molkentin J | title = C18:1, C18:2 and C18:3 trans and cis fatty acid isomers including conjugated cis delta 9, trans delta 11 linoleic acid (CLA) as well as total fat composition of German human milk lipids | journal = Die Nahrung | volume = 43 | issue = 4 | pages = 233–44 | date = August 1999 | pmid = 10481820 | doi = 10.1002/(SICI)1521-3803(19990801)43:4<233::AID-FOOD233>3.0.CO;2-B }}</ref><ref>{{cite journal | vauthors = Friesen R, Innis SM | title = Trans fatty acids in human milk in Canada declined with the introduction of trans fat food labeling | journal = The Journal of Nutrition | volume = 136 | issue = 10 | pages = 2558–61 | date = October 2006 | pmid = 16988126 | doi = 10.1093/jn/136.10.2558 | doi-access = free }}</ref>

The principal proteins are alpha-[[lactalbumin]], [[lactoferrin]] (apo-lactoferrin), IgA, [[lysozyme]], and [[serum albumin]]. In an acidic environment such as the [[stomach]], alpha-lactalbumin [[protein folding|unfolds]] into a different form and binds [[oleic acid]] to form a complex called [[Experimental cancer treatment#HAMLET (human alpha-lactalbumin made lethal to tumor cells)|HAMLET]] that kills [[tumor]] cells.{{citation needed|date=November 2023}} This is thought to contribute to the protection of breastfed babies against cancer.<ref>{{cite book |doi=10.1016/S0065-230X(03)88302-1 |title=HAMLET kills tumor cells by an apoptosis-like mechanism—cellular, molecular, and therapeutic aspects |series=Advances in Cancer Research |date=2003 |last1=Svanborg |first1=Catharina |last2=Ågerstam |first2=Helena |last3=Aronson |first3=Annika |last4=Bjerkvig |first4=Rolf |last5=Düringer |first5=Caroline |last6=Fischer |first6=Walter |last7=Gustafsson |first7=Lotta |last8=Hallgren |first8=Oskar |last9=Leijonhuvud |first9=Irene |last10=Linse |first10=Sara |last11=Mossberg |first11=Ann-Kristin |last12=Nilsson |first12=Hanna |last13=Pettersson |first13=Jenny |last14=Svensson |first14=Malin |volume=88 |pages=1–29 |pmid=12665051 |isbn=978-0-12-006688-9 }}</ref>

Non-protein nitrogen-containing compounds, making up 25% of the milk's nitrogen, include [[urea]], [[uric acid]], [[creatine]], [[creatinine]], [[amino acid]]s, and [[nucleotide]]s.<ref>{{cite journal | vauthors = Jenness R | title = The composition of human milk | journal = Seminars in Perinatology | volume = 3 | issue = 3 | pages = 225–39 | date = July 1979 | pmid = 392766 }}</ref><ref>{{cite journal | vauthors = Thorell L, Sjöberg LB, Hernell O | title = Nucleotides in human milk: sources and metabolism by the newborn infant | journal = Pediatric Research | volume = 40 | issue = 6 | pages = 845–52 | date = December 1996 | pmid = 8947961 | doi = 10.1203/00006450-199612000-00012 | s2cid = 36817657 | doi-access = free }}</ref> Breast milk has [[circadian]] variations; some of the nucleotides are more commonly produced during the night, others during the day.<ref>{{cite journal | vauthors = Sánchez CL, Cubero J, Sánchez J, Chanclón B, Rivero M, Rodríguez AB, Barriga C | title = The possible role of human milk nucleotides as sleep inducers | journal = Nutritional Neuroscience | volume = 12 | issue = 1 | pages = 2–8 | date = February 2009 | pmid = 19178785 | doi = 10.1179/147683009X388922 | s2cid = 30414322 | url = http://www.websciences.org/cftemplate/NAPS/archives/indiv.cfm?ID=20084074 | archive-url = https://web.archive.org/web/20090812180552/http://www.websciences.org/cftemplate/NAPS/archives/indiv.cfm?ID=20084074 | archive-date = 2009-08-12 | url-access = subscription }}</ref>

Mother's milk has been shown to supply [[endocannabinoid]]s (the natural neurotransmitters that [[cannabis]] simulates) [[2-Arachidonoylglycerol|2-arachidonoylglycerol]],<ref>{{cite journal | vauthors = Fride E, Bregman T, Kirkham TC | title = Endocannabinoids and food intake: newborn suckling and appetite regulation in adulthood | journal = Experimental Biology and Medicine | volume = 230 | issue = 4 | pages = 225–34 | date = April 2005 | pmid = 15792943 | doi = 10.1177/153537020523000401 | s2cid = 25430588 | url = http://www.ebmonline.org/cgi/reprint/230/4/225.pdf | access-date = 2007-10-23 | archive-date = 2009-08-02 | archive-url = https://web.archive.org/web/20090802181308/http://www.ebmonline.org/cgi/reprint/230/4/225.pdf }}</ref> [[anandamide]],<ref>[http://www.nel.edu/pdf_/25_12/NEL251204A01_Fride_.pdf The Endocannabinoid-CB Receptor System: Importance for development and in pediatric disease] {{Webarchive|url=https://web.archive.org/web/20160402083340/http://www.nel.edu/pdf_/25_12/NEL251204A01_Fride_.pdf |date=2016-04-02 }} Neuroendocrinology Letters Nos.1/2, Feb–Apr Vol.25, 2004.</ref><ref>[http://www.cannabis-med.org/data/pdf/2002-03-04-3.pdf Cannabinoids and Feeding: The Role of the Endogenous Cannabinoid System as a Trigger for Newborn Suckling] {{Webarchive|url=https://web.archive.org/web/20201001042840/http://www.cannabis-med.org/data/pdf/2002-03-04-3.pdf |date=2020-10-01 }} Women and Cannabis: Medicine, Science, and Sociology, 2002 The Haworth Press, Inc.</ref> [[oleoylethanolamide]],<ref name=Wu2016>{{cite journal | vauthors = Wu J, Gouveia-Figueira S, Domellöf M, Zivkovic AM, Nording ML | title = Oxylipins, endocannabinoids, and related compounds in human milk: Levels and effects of storage conditions | journal = Prostaglandins & Other Lipid Mediators | volume = 122 | pages = 28–36 | date = January 2016 | pmid = 26656029 | doi = 10.1016/j.prostaglandins.2015.11.002 }}</ref> [[palmitoylethanolamide]],<ref name="Wu2016" /> [[N-arachidonoyl glycine]],<ref name="Wu2016" /> eicosapentaenoyl ethanolamide,<ref name="Wu2016" /> docosahexaenoyl ethanolamide,<ref name="Wu2016" /> N-palmitoleoyl-ethanolamine,<ref name="Wu2016" /> dihomo-γ-linolenoylethanolamine,<ref name="Wu2016" /> N-stearoylethanolamine,<ref name="Wu2016" /> prostaglandin F2alpha ethanolamides<ref name="Wu2016" /> and prostaglandin F2 ethanolamides,<ref name="Wu2016" /> Palmitic acid esters of hydroxy-stearic acids (PAHSAs).<ref>{{cite journal | last1 = Brezinova | first1 = M | year = 2018| title = Levels of palmitic acid ester of hydroxystearic acid (PAHSA) are reduced in the breast milk of obese mothers | journal = Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids | volume = 1863| issue = 2| pages = 126–131| doi = 10.1016/j.bbalip.2017.11.004 | pmid = 29154942 }}</ref> They may act as an appetite stimulant, but they also regulate appetite so infants do not eat too much. That may be why formula-fed babies have a higher caloric intake than breastfed babies.<ref>{{cite news | url=https://www.theguardian.com/lifeandstyle/2012/jun/16/breasts-breastfeeding-milk-florence-williams | location=London | work=The Guardian | first=Florence | last=Williams | title=The wonder of breasts | date=2012-06-16 | access-date=2016-12-14 | archive-date=2021-04-11 | archive-url=https://web.archive.org/web/20210411004826/http://www.theguardian.com/lifeandstyle/2012/jun/16/breasts-breastfeeding-milk-florence-williams | url-status=live }}</ref>

Breast milk is not [[Sterilization (microbiology)|sterile]] and has [[Human milk microbiome|its own microbiome]], but contains as many as 600 different species of [[Human milk microbiome|various bacteria]], including beneficial ''[[Bifidobacterium]] breve'', ''B.&nbsp;adolescentis'', ''B.&nbsp;longum'', ''B.&nbsp;bifidum'', and ''B.&nbsp;dentium'', which contribute to colonization of the infant gut.<ref>{{cite journal | vauthors = Martín R, Jiménez E, Heilig H, Fernández L, Marín ML, Zoetendal EG, Rodríguez JM | title = Isolation of bifidobacteria from breast milk and assessment of the bifidobacterial population by PCR-denaturing gradient gel electrophoresis and quantitative real-time PCR | journal = Applied and Environmental Microbiology | volume = 75 | issue = 4 | pages = 965–9 | date = February 2009 | pmid = 19088308 | pmc = 2643565 | doi = 10.1128/AEM.02063-08 | bibcode = 2009ApEnM..75..965M }}</ref> As a result, it can be defined as a probiotic food, depending on how one defines "[[probiotic]]".<ref>{{cite journal | vauthors = McGuire MK, McGuire MA | title = Human milk: mother nature's prototypical probiotic food? | journal = Advances in Nutrition | volume = 6 | issue = 1 | pages = 112–23 | date = January 2015 | pmid = 25593150 | pmc = 4288270 | doi = 10.3945/an.114.007435 }}</ref> Breast milk also contains a variety of [[somatic cell]]s and [[stem cell]]s and the proportion of each cell type differs from individual to individual.<ref name=":02">{{cite journal | vauthors = Witkowska-Zimny M, Kaminska-El-Hassan E | title = Cells of human breast milk | journal = Cellular & Molecular Biology Letters | volume = 22 | issue = 1 | article-number = 11 | date = 2017-07-13 | pmid = 28717367 | pmc = 5508878 | doi = 10.1186/s11658-017-0042-4 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Indumathi S, Dhanasekaran M, Rajkumar JS, Sudarsanam D | title = Exploring the stem cell and non-stem cell constituents of human breast milk | journal = Cytotechnology | volume = 65 | issue = 3 | pages = 385–93 | date = May 2013 | pmid = 22940915 | pmc = 3597173 | doi = 10.1007/s10616-012-9492-8 }}</ref> The somatic cells are mainly [[wiktionary:lactocyte|lactocytes]] and [[myoepithelial cell]]s derived from the mother's mammary glands.<ref>{{cite journal |last1=Twigger |first1=Alecia-Jane |last2=Hepworth |first2=Anna R. |last3=Tat Lai |first3=Ching |last4=Chetwynd |first4=Ellen |last5=Stuebe |first5=Alison M. |last6=Blancafort |first6=Pilar |last7=Hartmann |first7=Peter E. |last8=Geddes |first8=Donna T. |last9=Kakulas |first9=Foteini |title=Gene expression in breastmilk cells is associated with maternal and infant characteristics |journal=Scientific Reports |date=10 August 2015 |volume=5 |issue=1 |article-number=12933 |doi=10.1038/srep12933 |pmid=26255679 |pmc=4542700 |bibcode=2015NatSR...512933T }}</ref> The stem cells found in human breast milk have been shown to be able to differentiate into a variety of other cells involved in the production of bodily [[Tissue (biology)|tissues]] and a small proportion of these cross over the nursing infant's intestinal tract into the bloodstream to reach certain organs and transform into fully functional cells.<ref>{{cite journal | vauthors = Ninkina N, Kukharsky MS, Hewitt MV, Lysikova EA, Skuratovska LN, Deykin AV, Buchman VL | title = Stem cells in human breast milk | journal = Human Cell | volume = 32 | issue = 3 | pages = 223–230 | date = July 2019 | pmid = 30972555 | pmc = 6570695 | doi = 10.1007/s13577-019-00251-7 }}</ref> Because of its diverse population of cells and multifarious functions, researchers have argued that breast milk should be considered a living tissue.<ref name=":02" />

Breast milk contains a unique type of sugars, [[human milk oligosaccharide]]s (HMOs), which were not present in traditional infant formula, however they are increasingly added by many manufacturers. HMOs are not digested by the infant but help to make up the [[intestinal flora]].<ref>{{cite book |doi=10.1016/B978-044451967-2/00128-8 |chapter=Milk Oligosaccharides |title=Comprehensive Glycoscience |date=2007 |last1=Urashima |first1=T. |last2=Asakuma |first2=S. |last3=Messer |first3=M. |pages=695–724 |isbn=978-0-444-51967-2 }}</ref> They act as [[decoy receptors]] that block the attachment of disease causing [[pathogens]], which may help to prevent infectious diseases.<ref>{{cite journal |last1=Maginnis |first1=Melissa S. |title=Virus–Receptor Interactions: The Key to Cellular Invasion |journal=Journal of Molecular Biology |date=August 2018 |volume=430 |issue=17 |pages=2590–2611 |doi=10.1016/j.jmb.2018.06.024 |pmid=29924965 |pmc=6083867 }}</ref> They also alter [[immune cell]] responses, which may benefit the infant. As of 2015 more than a hundred different HMOs have been identified; both the number and composition vary between women and each HMO may have a distinct functionality.<ref name="PubMed">{{cite journal | vauthors = Bode L | title = The functional biology of human milk oligosaccharides | journal = Early Human Development | volume = 91 | issue = 11 | pages = 619–22 | date = November 2015 | pmid = 26375354 | doi = 10.1016/j.earlhumdev.2015.09.001 }}</ref>

The breast milk of diabetic mothers has been shown to have a different composition from that of non-diabetic mothers. It may contain elevated levels of glucose and insulin and decreased polyunsaturated fatty acids. A dose-dependent effect of diabetic breast milk on increasing language delays in infants has also been noted, although doctors recommend that diabetic mothers breastfeed despite this potential risk.<ref>{{cite journal | vauthors = Rodekamp E, Harder T, Kohlhoff R, Dudenhausen JW, Plagemann A | title = Impact of breast-feeding on psychomotor and neuropsychological development in children of diabetic mothers: role of the late neonatal period | journal = Journal of Perinatal Medicine | volume = 34 | issue = 6 | pages = 490–6 | year = 2006 | pmid = 17140300 | doi = 10.1515/JPM.2006.095 | s2cid = 26423226 }}</ref>

Women [[breastfeeding]] should consult with their physician regarding substances that can be unwittingly passed to the infant via breast milk, such as [[alcohol (drug)|alcohol]], viruses ([[HIV]] or [[HTLV-1]]), or medications.<ref>{{Cite book |first=Margaret |last=Strock |title=Medications |date=2002 |publisher=Dept. of Health and Human Services, Public Health Service, National Institutes of Health, National Institute of Mental Health |oclc=52113208 }}</ref> Even though most infants infected with HIV contract the disease from breastfeeding, most infants that are breastfed by their HIV positive mothers never contract the disease.<ref name="Wahl_2015">{{cite journal | vauthors = Wahl A, Baker C, Spagnuolo RA, Stamper LW, Fouda GG, Permar SR, Hinde K, Kuhn L, Bode L, Aldrovandi GM, Garcia JV | title = Breast Milk of HIV-Positive Mothers Has Potent and Species-Specific In Vivo HIV-Inhibitory Activity | journal = Journal of Virology | volume = 89 | issue = 21 | pages = 10868–78 | date = November 2015 | pmid = 26292320 | pmc = 4621099 | doi = 10.1128/JVI.01702-15 }}</ref> While this paradoxical phenomenon suggests that the risk of HIV transmission between an HIV positive mother and her child via breastfeeding is small, studies have also shown that feeding infants with breast milk of HIV-positive mothers can actually have a preventative effect against HIV transmission between the mother and child.<ref name="Wahl_2015" /> This inhibitory effect against the infant contracting HIV is likely due to unspecified factors exclusively present in breast milk of HIV-positive mothers.<ref name="Wahl_2015" />

Most women that do not breastfeed use [[infant formula]], but breast milk donated by volunteers to human milk banks can be obtained by prescription in some countries.<ref>{{cite web |url=http://www.womenshealth.gov/breastfeeding/index.cfm?page=359 |title=Breastfeeding &#124; Health benefits for mother and baby |publisher=womenshealth.gov |date=2010-08-01 |access-date=2011-10-26 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304002201/http://www.womenshealth.gov/breastfeeding/index.cfm?page=359 }}</ref> In addition, research has shown that women who rely on infant formula could minimize the gap between the level of immunity protection and cognitive abilities a breastfed child benefits from versus the degree to which a bottle-fed child benefits from them.<ref>{{cite journal |last1=Martin |first1=Camilia |last2=Ling |first2=Pei-Ra |last3=Blackburn |first3=George |title=Review of Infant Feeding: Key Features of Breast Milk and Infant Formula |journal=Nutrients |date=11 May 2016 |volume=8 |issue=5 |page=279 |doi=10.3390/nu8050279 |pmid=27187450 |pmc=4882692 |doi-access=free }}</ref> This can be done by supplementing formula-fed infants with bovine [[milk fat globule membrane]]s (MFGM) meant to mimic the positive effects of the MFGMs which are present in human breast milk.<ref>{{cite journal | vauthors = Hernell O, Timby N, Domellöf M, Lönnerdal B | title = Clinical Benefits of Milk Fat Globule Membranes for Infants and Children | journal = The Journal of Pediatrics | volume = 173 Suppl | pages = S60–5 | date = June 2016 | pmid = 27234413 | doi = 10.1016/j.jpeds.2016.02.077 | doi-access = free }}</ref>

== Storage of expressed breast milk ==
[[File:Bottle of Pumped Breast Milk.jpg|thumb|upright|Bottle of [[Breast pump|pumped]] breast milk]]
<!--[[Image:Breast milk storage containers bottles.JPG|thumb|Breast milk storage containers.]]-->
Expressed breast milk can be [[Breastmilk storage and handling|stored]]. [[Lipase]] may cause thawed milk to taste soapy or rancid due to milk fat breakdown. It is still safe to use, and most babies will drink it. Scalding it will prevent rancid taste at the expense of antibodies.<ref>{{cite web
 |url          = http://www.llli.org/faq/milkstorage.html
 |title        = What are the LLLI guidelines for storing my pumped milk?
 |access-date  = 2014-07-16
 |archive-url  = https://web.archive.org/web/20140701095138/http://www.llli.org/faq/milkstorage.html
 |archive-date = 2014-07-01
 }}</ref> It should be stored with airtight seals. <!-- AAP, next reference. --> Some plastic bags are designed for storage periods of less than 72 hours. Others can be used for up to 12 months if frozen. This table describes safe storage time limits.<ref>[http://www.bfmed.org/Resources/Download.aspx?filename=Protocol_8.pdf Protocol #8: Human milk storage information for home use for healthy full-term infants.] {{Webarchive|url=https://web.archive.org/web/20201029024108/https://www.bfmed.org/Resources/Download.aspx?Filename=Protocol_8.pdf |date=2020-10-29 }} Academy of Breastfeeding Medicine Protocol.</ref>

{| class="wikitable"
|-
! Place of storage
! colspan=2|Temperature
! Maximum storage time
|-
| In a room
| {{cvt|25|C|F|disp=table|abbr=on}}
| Six to eight hours
|-
| Insulated [[thermal bag]] with ice packs
|
|
| Up to 24 hours
|-
| In a [[refrigerator]]
| {{cvt|4|C|F|disp=table|abbr=on}}
| Up to five days
|-
| [[Freezer]] compartment inside a [[refrigerator]]
| {{cvt|-15|C|F|disp=table|abbr=on}}
| Two weeks
|-
| A combined [[refrigerator]] and [[Refrigerator#Freezer|freezer]] with separate doors
| {{cvt|-18|C|F|disp=table|abbr=on}}
| Three to six months
|-
| Chest or upright manual defrost deep [[Refrigerator#Freezer|freezer]]
| {{cvt|-20|C|F|disp=table|abbr=on}}
| Six to twelve months
|}

== Comparison to other milks ==
All [[mammal]]ian species produce milk, but the composition of milk for each species varies widely and other kinds of milk are often very different from human breast milk. As a rule, the milk of mammals that nurse frequently (including human babies) is less rich, or more watery, than the milk of mammals whose young nurse less often. Human milk is noticeably thinner and sweeter than cow's milk.

Whole cow's milk contains too little [[iron]], [[retinol]], [[vitamin E]], [[vitamin C]], [[vitamin D]], [[unsaturated fat]]s or essential [[fatty acid]]s for human babies.<ref>Department of Health, 1994. Weaning and the weaning diet. Report of the Working Group on the Weaning Diet of the Committee on Medical Aspects of Food Policy. London: HMSO. Report on Health and Social Subjects No 45.</ref><ref name=vegcomp5>{{Cite web |url=http://www.vegetarian.org.uk/campaigns/whitelies/wlreport05.shtml |title=Vegetarian & Vegan Foundation<!-- Bot generated title --> |access-date=2013-01-07 |archive-url=https://web.archive.org/web/20140821103225/http://www.vegetarian.org.uk/campaigns/whitelies/wlreport05.shtml |archive-date=2014-08-21 }}</ref><ref name=vegcomp6>{{Cite web |url=http://www.vegetarian.org.uk/campaigns/whitelies/wlreport06.shtml |title=Vegetarian & Vegan Foundation<!-- Bot generated title --> |access-date=2013-01-07 |archive-url=https://web.archive.org/web/20140811224245/http://www.vegetarian.org.uk/campaigns/whitelies/wlreport06.shtml |archive-date=2014-08-11 }}</ref><ref>FSA, 2002. McCance and Widdowson's The Composition of Foods, 6th summary edition. Cambridge, England, Royal Society of Chemistry.</ref> Whole cow's milk also contains too much [[protein]], [[sodium]], [[potassium]], [[phosphorus]] and [[chloride]] which may put a strain on an infant's immature [[kidneys]]. In addition, the proteins, fats and [[calcium]] in whole cow's milk are more difficult for an infant to digest and absorb than the ones in breast milk.<ref name="vegcomp5" /><ref>MedlinePlus Medical Encyclopedia: [https://www.medlineplus.gov/ency/article/002448.htm Cow's milk for infants and children] </ref><ref>{{cite journal |vauthors=Martinez GA, Ryan AS, Malec DJ | year = 1985 | title = Nutrient intakes of American infants and children fed cow's milk or infant formula | journal = American Journal of Diseases of Children | volume = 139 | issue = 10| pages = 1010–8 | doi=10.1001/archpedi.1985.02140120056027| pmid = 4036886 }}</ref>

The composition of marsupial and monotreme milk contains essential nutrients, growth factors and immunological properties to support the development of joeys and puggles.<ref name="Marsupial and monotreme milk – a re"/>

{| class="wikitable"
|+Comparing milks (per cup [1cup=246g] in SI units of measurement)<ref>{{Cite web |title=Breastfeeding: Human Milk Versus Animal Milk |url=http://www.nutritionmd.org/nutrition_tips/nutrition_tips_infant_nutrition/breastfeeding_milks.html |url-status=usurped |archive-url=https://web.archive.org/web/20081122024542/http://www.nutritionmd.org/nutrition_tips/nutrition_tips_infant_nutrition/breastfeeding_milks.html |archive-date=22 November 2008}}</ref><ref>{{Cite web |title=Milk, human, mature, fluid Nutrition Facts & Calories |url=http://nutritiondata.self.com/facts/dairy-and-egg-products/95/2 |url-status=usurped |archive-url=https://web.archive.org/web/20211129080542/https://nutritiondata.self.com/facts/dairy-and-egg-products/95/2 |archive-date=29 November 2021 |access-date=10 June 2018}}</ref>

!'''[[Nutrient]]'''
!'''Human milk'''
!'''[[Cow]] milk (3.25% fat)'''
!'''[[Goat]] milk'''
|-
|[[Calories]] (Kcal)
|172
|146
|168
|-
|[[Water]] (g)
|215
|215
|212
|-
|[[Protein]] (g)
|2.5
|7.9
|8.7
|-
|[[Fat]] (g)
|10.8
|7.9
|10.1
|-
|[[Saturated fat]] (g)
|4.9
|4.6
|6.5
|-
|[[Monounsaturated fat]] (g)
|4.1
|2.0
|2.7
|-
|[[Polyunsaturated fat]] (g)
|1.2
|0.5
|0.4
|-
|[[Omega-3 fatty acid]]s (mg)
|128
|183
|97.6
|-
|[[Omega-6 fatty acid]]s (mg)
|920
|293
|266
|-
|[[Cholesterol]] (mg)
|34.4
|24.4
|26.8
|-
|[[Carbohydrate]] (g)
|17.0
|11.0
|10.9
|-
|[[Sugar]]s (g)
|17.0
|11.0
|10.9
|-
|[[Vitamin A]] (IU)
|522
|249
|483
|-
|[[Vitamin C]] (mg)
|12.3
|0
|3.2
|-
|[[Vitamin D]] (IU) *
|9.8
|97.6
|29.3
|-
|[[Vitamin E]] (mg)
|0.2
|0.1
|0.2
|-
|[[Vitamin K]] (mcg)
|0.7
|0.5
|0.7
|-
|[[Thiamin]] (mg)
|0.0
|0.1
|0.1
|-
|[[Riboflavin]] (mg)
|0.1
|0.4
|0.3
|-
|[[Niacin (nutrient)|Niacin]] (mg)
|0.4
|0.3
|0.7
|-
|[[Vitamin B6]] (mg)
|0.0
|0.1
|0.1
|-
|[[Folate]] (mcg)
|12
|12
|2
|-
|[[Vitamin B12]] (mcg)
|0.1
|1.1
|0.2
|-
|[[Pantothenic acid]] (mg)
|0.5
|0.9
|0.8
|-
|[[Choline]] (mg)
|39.4
|34.9
|39.0
|-
|[[Calcium]] (mg)
|79
|276
|327
|-
|[[Iron]] (mg)
|0.07
|0.07
|0.12
|-
|[[Magnesium]] (mg)
|7.4
|24.4
|34.2
|-
|[[Phosphorus]] (mg)
|34.4
|222
|271
|-
|[[Potassium]] (mg)
|125
|349
|498
|-
|[[Sodium]] (mg)
|42
|98
|122
|-
|[[Zinc]] (mg)
|0.4
|1.0
|0.7
|-
|[[Copper]] (mg)
|0.1
|0.0
|0.1
|-
|[[Manganese]] (mg)
|0.1
|0.0
|0.0
|-
|[[Selenium]] (mcg)
|4.4
|9.0
|3.4
|}
{{asterisk}} Note: Milk is generally fortified with vitamin D in the U.S. and Canada. Non-fortified milk contains only 2&nbsp;IU per 3.5 oz.

==Effects of medications and other substances on milk content==
{{Main|Breastfeeding and medications}}
{{Further|Breast milk-mediated drug delivery}}
Almost all medicines, or drugs, pass into breastmilk in small amounts by a [[concentration gradient]].<ref name="Drugs in human milk. Clinical pharm">{{cite journal | vauthors = Atkinson HC, Begg EJ, Darlow BA | title = Drugs in human milk. Clinical pharmacokinetic considerations | journal = Clinical Pharmacokinetics | volume = 14 | issue = 4 | pages = 217–40 | date = April 1988 | pmid = 3292101 | doi = 10.2165/00003088-198814040-00003 | s2cid = 33029715 }}</ref> The amount of the drug bound by maternal [[plasma proteins]], the size of the drug molecule, the pH and/or [[pKa]] of the drug, and the [[lipophilicity]] of the drug all determine whether and how much of the drug will pass into breastmilk.<ref name=":3">{{cite journal | vauthors = Hotham N, Hotham E | title = Drugs in breastfeeding | journal = Australian Prescriber | volume = 38 | issue = 5 | pages = 156–9 | date = October 2015 | pmid = 26648652 | pmc = 4657301 | doi = 10.18773/austprescr.2015.056 }}</ref> Medications that are mostly non-protein bound, low in [[molecular weight]], and highly lipid-soluble are more likely to enter the breast milk in larger quantities.<ref name=":2">{{cite journal | vauthors = Spencer JP, Gonzalez LS, Barnhart DJ | title = Medications in the breast-feeding mother | journal = American Family Physician | volume = 64 | issue = 1 | pages = 119–26 | date = July 2001 | pmid = 11456429 | url = https://www.aafp.org/afp/2001/0701/p119.html | access-date = 2019-08-02 | archive-date = 2019-07-03 | archive-url = https://web.archive.org/web/20190703130557/https://www.aafp.org/afp/2001/0701/p119.html | url-status = live }}</ref> Some drugs have no effect on the baby and can be used whilst breastfeeding, while other medications may be dangerous and harmful to the infant.<ref name="NIH2014">{{cite web | url = https://www.womenshealth.gov/files/assets/docs/breastfeeding/owh_fs_breastfeeding_7-25-2014.pdf | publisher = Office on Women's Health, U.S. Department of Health and Human Services | date = 2014 | access-date = 20 July 2017 | title = Breastfeeding | archive-date = 14 May 2017 | archive-url = https://web.archive.org/web/20170514000256/https://www.womenshealth.gov/files/assets/docs/breastfeeding/owh_fs_breastfeeding_7-25-2014.pdf }}{{PD-notice}}</ref><ref name=":2" />

Some medications considered generally safe for use by a breastfeeding mother, with a doctor's or pharmacist's advice, include simple analgesics or pain killers such as [[Paracetamol|paracetamol/acetaminophen]],<ref>{{Cite web |title=Breastfeeding and Medication |url=http://www.aap.org/en-us/Pages/Breastfeeding-and-Medication.aspx |archive-url=https://web.archive.org/web/20190802213426/https://www.aap.org/en-us/Pages/Breastfeeding-and-Medication.aspx |archive-date=2019-08-02 |access-date=2019-08-02 |website=AAP.org |language=en-US}}</ref> anti-hypertensives such as the [[ACE inhibitor|ACE-inhibitors]] [[enalapril]] and [[captopril]], anti-depressants of the [[SSRI]] and [[SNRI]] classes, and medications for gastroesophageal reflux such as [[omeprazole]] and [[ranitidine]].<ref name=":5">{{cite journal |vauthors=Rowe H, Baker T, Hale TW |date=February 2013 |title=Maternal medication, drug use, and breastfeeding |journal=Pediatric Clinics of North America |series=Breastfeeding Updates for the Pediatrician |volume=60 |issue=1 |pages=275–94 |doi=10.1016/j.pcl.2012.10.009 |pmid=23178070}}</ref>

Conversely, there are medications that are known to be toxic to the baby and thus should not be used in breastfeeding mothers, such as [[chemotherapeutic agents]] which are [[cytotoxic]] like [[cyclosporine]],<ref name=":4">{{cite journal |last1=American Academy of Pediatrics Committee on |first1=Drugs |title=The Transfer of Drugs and Other Chemicals Into Human Milk |journal=Pediatrics |date=September 2001 |volume=108 |issue=3 |pages=776–789 |doi=10.1542/peds.108.3.776 |pmid=11533352 |s2cid=27763768 |doi-access=free}}</ref> [[immunosuppressants]] like [[methotrexate]],<ref name=":4" /> [[amiodarone]], or [[lithium]].<ref name=":2" /><ref name=":3" />

Furthermore, [[drugs of abuse]], such as cocaine, amphetamines, heroin, and marijuana cause adverse effects on the infant during breastfeeding. Adverse effects include seizures, tremors, restlessness, and diarrhea.<ref name=":4" />

To reduce infant exposure to medications used by the mother, use topical therapy or avoid taking the medication during breastfeeding times when possible.<ref name="Drugs in human milk. Clinical pharm"/>

Hormonal products and combined oral contraceptives should be avoided during the early postpartum period as they can interfere with lactation.<ref name=":5" />

There are some medications that may stimulate the production of breast milk. These medications may be beneficial in cases where women with [[hypothyroidism]] may be unable to produce milk.<ref name="NIH2017">{{cite web|title=Thyroid Disease & Pregnancy|url=https://www.niddk.nih.gov/health-information/endocrine-diseases/pregnancy-thyroid-disease|publisher=Office on Women's Health, U.S. Department of Health and Human Services|access-date=20 July 2017|date=1 February 2017|archive-date=12 July 2017|archive-url=https://web.archive.org/web/20170712111551/https://www.niddk.nih.gov/health-information/endocrine-diseases/pregnancy-thyroid-disease|url-status=live}}{{PD-notice}}</ref><ref name="ATA">{{cite web | title = Postpartum Thyroiditis | publisher = American Thyroid Association | access-date = 20 July 2017 | date = 2014 | url = http://www.thyroid.org/wp-content/uploads/patients/brochures/Postpartum_Thyroiditis_brochure.pdf | archive-date = 20 June 2019 | archive-url = https://web.archive.org/web/20190620165715/https://www.thyroid.org/wp-content/uploads/patients/brochures/Postpartum_Thyroiditis_brochure.pdf | url-status = live }}</ref> A Cochrane review looked at the drug domperidone (10&nbsp;mg three times per day) with results showing a significant increase in volume of milk produced over a period of one to two weeks.<ref>{{cite journal | vauthors = Donovan TJ, Buchanan K | title = Medications for increasing milk supply in mothers expressing breastmilk for their preterm hospitalised infants | journal = The Cochrane Database of Systematic Reviews | issue = 3 | article-number = CD005544 | date = March 2012 | pmid = 22419310 | doi = 10.1002/14651858.cd005544.pub2 | pmc = 11747959 }}</ref> However, another review concluded little evidence that use of domperidone and metoclopramide to enhance milk supply works. Instead, non-pharmacological approaches such as support and more frequent breastfeeding may be more efficacious.<ref name=":3" />

Finally, there are other substances besides medications that may appear in breast milk. [[Alcohol (drug)|Alcohol]] use during pregnancy carries a significant risk of serious birth defects, but consuming alcohol after the birth of the infant is considered safe.<ref name="who2">{{cite web|url=http://apps.who.int/iris/bitstream/10665/107130/1/9789241548731_eng.pdf?ua=1|title=Guidelines for the identification and management of substance use and substance use disorders in pregnancy|publisher=World Health Organization|access-date=11 August 2017|date=2014|archive-date=14 May 2017|archive-url=https://web.archive.org/web/20170514012719/http://apps.who.int/iris/bitstream/10665/107130/1/9789241548731_eng.pdf?ua=1|url-status=live}}</ref> High [[caffeine]] intake by breastfeeding mothers may cause their infants to become irritable or have trouble sleeping.<ref name=":3" /> A meta-analysis has shown that breastfeeding mothers who smoke expose their infants to nicotine, which may cause respiratory illnesses, including [[otitis media]] in the nursing infant.<ref name=":4" />

== Market ==
{{main|human milk bank}}
There is a commercial [[Market (economics)|market]] for human breast milk, both in the form of a [[wet nurse]] service and as a milk product.

As a product, breast milk is exchanged by [[human milk bank]]s, as well as directly between milk donors and customers as mediated by websites on the internet. Human milk banks generally have standardized measures for screening donors and storing the milk, sometimes even offering [[pasteurization]], while milk donors on websites vary in regard to these measures. A study in 2013 came to the conclusion that 74% of breast milk samples from providers found from websites were colonized with [[gram-negative bacteria]] or had more than 10,000 [[colony-forming unit]]s/mL of [[aerobic bacteria]].<ref name="Keim2013">{{cite journal | vauthors = Keim SA, Hogan JS, McNamara KA, Gudimetla V, Dillon CE, Kwiek JJ, Geraghty SR | title = Microbial contamination of human milk purchased via the Internet | journal = Pediatrics | volume = 132 | issue = 5 | pages = e1227–35 | date = November 2013 | pmid = 24144714 | pmc = 4530303 | doi = 10.1542/peds.2013-1687 }}</ref> Bacterial growth happens during transit.<ref name="Keim2013" /> According to the FDA, bad bacteria in food ''at room temperature'' can double every 20 minutes.<ref>{{cite web |title=Refrigerator Thermometers: Cold Facts about Food Safety |url=https://www.fda.gov/food/resourcesforyou/consumers/ucm253954.htm |website=U.S. Food and Drug Administration |date=14 September 2021 |access-date=6 August 2017 |archive-date=22 April 2019 |archive-url=https://web.archive.org/web/20190422141448/https://www.fda.gov/Food/ResourcesForYou/Consumers/ucm253954.htm }}</ref>

Human milk is considered to be healthier than cow's milk and infant formula when it comes to feeding an infant in the first six months of life, but only under extreme situations do international health organizations support feeding an infant breast milk from a healthy [[wet nurse]] rather than that of its biological mother.<ref name="Geraghty_2011">{{cite journal | vauthors = Geraghty SR, Heier JE, Rasmussen KM | title = Got milk? Sharing human milk via the Internet | journal = Public Health Reports | volume = 126 | issue = 2 | pages = 161–4 | date = 2011 | pmid = 21387943 | pmc = 3056026 | doi = 10.1177/003335491112600204 }}</ref> One reason is that the unregulated breast milk market is fraught with risks, such as drugs of abuse and prescription medications being present in donated breast milk.<ref name="Geraghty_2011" /> The transmission of these substances through breast milk can do more harm than good when it comes to the health outcomes of the infant recipient.<ref name="Geraghty_2011" />

===Fraud===
In the United States, the online marketplace for breast milk is largely unregulated and the high premium has encouraged [[food fraud]].<ref name="Oaklander2015">{{cite magazine |last1=OAKLANDER |first1=MANDY |title=Don't Buy Your Breast Milk Online, Scientists Say |url=https://time.com/3757041/breast-milk-buy-online/ |access-date=18 April 2024 |magazine=TIME |date=24 March 2015 |language=en |archive-date=18 April 2024 |archive-url=https://web.archive.org/web/20240418175443/https://time.com/3757041/breast-milk-buy-online/ |url-status=live }}</ref><ref>{{cite news |last1=Erika |first1=Edwards |last2=Briggs |first2=Bill |title=Breast Milk Bought Online Diluted With Cows Milk, Researchers Find |url=https://www.nbcnews.com/health/kids-health/breast-milk-scams-detected-samples-online-sellers-n335451 |access-date=18 April 2024 |work=NBC News |date=6 April 2015 |language=en |archive-date=18 April 2024 |archive-url=https://web.archive.org/web/20240418175452/https://www.nbcnews.com/health/kids-health/breast-milk-scams-detected-samples-online-sellers-n335451 |url-status=live }}</ref> Human breast milk may be diluted with other liquids to increase volume including [[cow's milk]], [[soy milk]], and [[water]], thus undermining its health benefits.<ref name="Oaklander2015"/><ref name="OaklanderApr2015">{{cite magazine |last1=OAKLANDER |first1=MANDY |title=This Is What's Actually in the Breast Milk You Buy Online |url=https://time.com/3772009/breast-milk-online/ |access-date=18 April 2024 |magazine=TIME |date=6 April 2015 |language=en |archive-date=18 April 2024 |archive-url=https://web.archive.org/web/20240418175441/https://time.com/3772009/breast-milk-online/ |url-status=live }}</ref>

A 2015 [[CBS]] article cites an editorial led by Dr. Sarah Steele in the ''[[Journal of the Royal Society of Medicine]]'', in which they say that "health claims do not stand up clinically and that [[Raw milk|raw human milk]] purchased online poses many health risks." CBS found a study from the Center for Biobehavioral Health at [[Nationwide Children's Hospital]] in [[Columbus, Ohio|Columbus]] that "found that 11 out of 102 breast milk samples purchased online were actually blended with [[cow's milk]]." The article also explains that milk purchased online may be improperly sanitized or stored, so it may contain food-borne illness and infectious diseases such as [[hepatitis]] and [[HIV]].<ref name="Kraft">{{cite news|last1=Kraft|first1=Amy|date=18 June 2015|title=Adult health craze for human breast milk poses risks|publisher=CBS|url=https://www.cbsnews.com/news/adult-craze-for-human-breast-milk-poses-risks/|access-date=13 January 2019|archive-date=13 January 2019|archive-url=https://web.archive.org/web/20190113182302/https://www.cbsnews.com/news/adult-craze-for-human-breast-milk-poses-risks/|url-status=live}}</ref>

== Consumption by adults ==
=== Restaurants and recipes ===
A minority of people, including restaurateurs Hans Lochen of [[Switzerland]] and Daniel Angerer of [[Austria]], who operate a restaurant in New York City, have used human breast milk, or at least advocated its use, as a substitute for cow's milk in [[dairy]] products and food [[recipe]]s.<ref>{{cite news| url=https://www.telegraph.co.uk/news/newstopics/howaboutthat/2976181/Swiss-restaurant-to-serve-meals-cooked-with-human-breast-milk.html |archive-url=https://ghostarchive.org/archive/20220112/https://www.telegraph.co.uk/news/newstopics/howaboutthat/2976181/Swiss-restaurant-to-serve-meals-cooked-with-human-breast-milk.html |archive-date=2022-01-12 |url-access=subscription |url-status=live | work=The Daily Telegraph | location=London | title=Swiss restaurant to serve meals cooked with human breast milk A Swiss gastronomist has stirred a controversy in the tranquil Alpine republic after announcing that he will serve meals cooked with human breast milk | date=2008-09-17 | access-date=2010-04-26}}{{cbignore}}</ref><ref>{{cite web | work = New York Daily News | title = Restaurant Drops Plan to Cook with Breast Milk | url = http://www.nydailynews.com/money/2008/09/18/2008-09-18_restaurant_drops_plan_to_cook_with_breas.html | first = Rosemary | last = Black | name-list-style = vanc | date = 18 September 2008 | access-date = 2009-06-18 | archive-date = 2011-08-05 | archive-url = https://web.archive.org/web/20110805032411/http://www.nydailynews.com/money/2008/09/18/2008-09-18_restaurant_drops_plan_to_cook_with_breas.html }}</ref> An icecreamist in London's Covent Garden, [[The Licktators]], started selling an ice cream named Baby Gaga in February 2011. Each serving cost £14. All the milk was donated by a Mrs Hiley who earned £15 for every 10 ounces and called it a "great recession beater".<ref>{{cite news | url=https://www.bbc.co.uk/news/uk-england-london-12569011 | work=BBC News | location=London | title=Breast milk ice cream goes on sale in Covent Garden | date=2011-02-24 | access-date=2011-03-07 | archive-date=2011-03-02 | archive-url=https://web.archive.org/web/20110302202137/http://www.bbc.co.uk/news/uk-england-london-12569011 | url-status=live }}</ref> The ice cream sold out on its first day. Despite the success of the new flavour, the Westminster Council officers removed the product from the menu to make sure that it was, as they said, "fit for human consumption."<ref>{{cite news | url=https://www.bbc.co.uk/news/uk-england-london-12615353 | work=BBC News | location=London | title=Baby Gaga breast milk ice cream seized for safety tests | date=2011-03-01 | access-date=2011-03-07 | archive-date=2011-03-02 | archive-url=https://web.archive.org/web/20110302052333/http://www.bbc.co.uk/news/uk-england-london-12615353 | url-status=live }}</ref> Tammy Frissell-Deppe, a family counsellor specialized in [[attachment parenting]], published a book, titled ''A Breastfeeding Mother's Secret Recipes'', providing a lengthy compilation of detailed food and beverage recipes containing human breast milk.<ref>{{cite book | first = Tammy | last = Frissell-Deppe | name-list-style = vanc | title = A Breastfeeding Mother's Secret Recipes: Breast milk Recipes, Fun Food for Kids and Quick Dishes! | location = Dracut, MA | publisher = JED Publishing | year = 2002 }}</ref> Human breast milk is not produced or distributed industrially or commercially, because the use of human breast milk as an adult food is considered unusual to the majority of [[culture]]s around the world, and most disapprove of such a practice.<ref>{{cite book|last1=Jelliffe|first1=Derrick B.|last2=Jelliffe|first2=E. F. Patrice | name-list-style = vanc |title=Human milk in the modern world: psychosocial nutritional and economic significance|date=1978|publisher=Oxford University Press|location=Oxford|isbn=978-0-19-264921-8}}</ref>

In Costa Rica, there have been trials to produce human [[cheese]], and [[custard]] from human milk, as an alternative to [[weaning]].<ref name="Nacion">''[http://wvw.nacion.com/ln_ee/2007/junio/17/aldea1131695.html Clínica busca cómo hacer queso de leche materna] {{Webarchive|url=https://web.archive.org/web/20201003052203/http://wvw.nacion.com/ln_ee/2007/junio/17/aldea1131695.html|date=2020-10-03}}'', [[Nación]], 17 June 2007</ref>

=== Bodybuilders ===
While there is no scientific evidence that shows that breast milk is advantageous for adults, according to several 2015 news sources, breast milk is being used by [[bodybuilders]] for its nutritional value. In a February 2015 [[ABC News (United States)|ABC News]] article, one former competitive body builder said, "It isn't common, but I've known people who have done this. It's certainly talked about quite a bit on the bodybuilding forums on the Internet." Calling bodybuilders "a strange breed of individuals", he said, "Even if this type of thing is completely unsupported by research, they're prone to gym lore and willing to give it a shot if there is any potential effect." At the time the article was written, in the U.S., the price of breast milk procured from milk banks that pasteurize the milk, and have expensive quality and safety controls, was about {{convert|10|$/USoz|$/ml}}, and the price in the alternative market online, bought directly from mothers, ranges from {{convert|1|-|4|$/USoz|$/ml|2}}, compared to cow's milk at about {{convert|3.44|$/USgal|$/USoz $/ml|4}}.<ref name="ABC News">{{cite web | url=https://abcnews.go.com/Health/body-builders-pounding-breast-milk/story?id=29020910 | title=Why Bodybuilders Are Pounding Down Breast Milk | work=ABC News | date=17 February 2015 | access-date=4 December 2015 | last=Neporent | first=Liz | name-list-style=vanc | archive-date=8 December 2015 | archive-url=https://web.archive.org/web/20151208173744/http://abcnews.go.com/Health/body-builders-pounding-breast-milk/story?id=29020910 | url-status=live }}</ref><ref>{{cite web | url=https://www.menshealth.com/fitness/a19530877/human-breast-milk-and-bodybuilding/ | title=Bodybuilders Are Drinking Human Breast Milk. Are They Insane, or Super Insane? | publisher=Men's Health | access-date=4 December 2015 | first=Michael | last=Easter | name-list-style=vanc | date=2015-02-19 | archive-date=2018-05-11 | archive-url=https://web.archive.org/web/20180511145942/https://www.menshealth.com/fitness/a19530877/human-breast-milk-and-bodybuilding/ | url-status=live }}</ref>

=== Erotic lactation ===
{{Expand section|date=October 2024}}
{{Main|Erotic lactation}}

For sexual purposes, some couples have decided to [[Lactation#Without pregnancy, induced_lactation, relactation|induce lactation]] outside a pregnancy through a practice called "Erotic lactation".

== Breast milk contamination ==
Breast milk is oftentimes used as an environmental bioindicator given its ability to accumulate certain chemicals, including organochlorine pesticides.<ref>{{Cite journal |last1=Mekonen |first1=Sablework |last2=Ambelu |first2=Argaw |last3=Wondafrash |first3=Mekitie |last4=Kolsteren |first4=Patrick |last5=Spanoghe |first5=Pieter |date=2021 |title=Exposure of infants to organochlorine pesticides from breast milk consumption in southwestern Ethiopia |journal=Scientific Reports |volume=11|issue=1 |page=22053 |doi=10.1038/s41598-021-01656-x |pmid=34764390 |pmc=8585979 |bibcode=2021NatSR..1122053M }}</ref> Research has found that certain organic contaminants such as [[Polychlorinated biphenyl|PCBs]], [[organochlorine pesticide]]s, [[Polychlorinated dibenzodioxins|PCDDs]], [[Polybrominated diphenyl ethers|PBDEs]], and [[DDT]] can contaminate breastmilk.<ref name=Solomon>{{cite journal |last1=Solomon |first1=Gina M |last2=Weiss |first2=Pilar M |title=Chemical contaminants in breast milk: time trends and regional variability. |journal=Environmental Health Perspectives |date=June 2002 |volume=110 |issue=6 |pages=A339-47 |doi=10.1289/ehp.021100339 |pmid=12055065 |pmc=1240888 }}</ref> According to research done in 2002, the levels of the organochlorine pesticides, PCBs, and dioxins have declined in breast milk in countries where these chemicals have been banned or otherwise regulated, while levels of PBDEs are rising.<ref name=Solomon/>

=== Pesticide contamination in breastmilk ===
Pesticides and other toxic substances [[bioaccumulate]]; i.e., creatures higher up the [[food chain]] will store more of them in their [[body fat]]. This is an issue in particular for the [[Inuit]], whose [[Inuit diet|traditional diet]] is predominantly meat. Studies are looking at the effects of [[polychlorinated biphenyls]] and [[persistent organic pollutants]] in the body; the breast milk of Inuit mothers is extraordinarily high in toxic compounds.<ref>{{cite book |last1=Cone |first1=Marla |title=Silent Snow: The Slow Poisoning of the Arctic |date=2007 |publisher=Open Road + Grove/Atlantic |isbn=978-1-55584-769-2 }}{{pn|date=June 2024}}</ref>

The CDC has provided some resources for breastfeeding mothers to reference for safe medication use, including [https://www.ncbi.nlm.nih.gov/books/NBK501922/ LactMed], [https://mothertobaby.org/ Mother to Baby], and [http://www.infantrisk.com/categories/breastfeeding The InfantRisk Center].<ref>{{Cite web |last=CDC |date=2018 |title=Prescription Medication Use |url=https://www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/vaccinations-medications-drugs/prescription-medication-use.html |access-date=2019-08-02 |website=Centers for Disease Control and Prevention |language=en-us |archive-date=2019-06-23 |archive-url=https://web.archive.org/web/20190623114642/https://www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/vaccinations-medications-drugs/prescription-medication-use.html |url-status=live }}</ref>

===Contamination effects of organochlorine pesticides on infants===
When a mother is exposed to organochlorine pesticides (OCP's), her infant can be exposed to these OCP's through breast milk intake. This result is supported by a study done in India, which revealed that in each lactation period there is a loss of OCPs from the mother's body involved in the nursing of their children. A longitudinal study was conducted to assess pesticide residues in human breast milk samples and evaluate the risk-exposure of infants to these pesticides from consumption of mother's milk in Ethiopia. The estimated daily intake (EDI) of infants in the present study was above provisional tolerable daily intake (PTDI) during the first month of breastfeeding which indicates that there is a health risk for infants consuming breast milk at an early stage of breastfeeding in the study areas. Based on these studies, the exposure of women during pregnancy to these OCPs may lead to various health problems for fetus such as low birth weight, disturbance of thyroid hormone, and neurodevelopmental delay.<ref>{{Cite journal |last1=Mekonen |first1=Seblework |last2=Ambelu |first2=Argaw |last3=Wondafrash |first3=Mekitie |last4=Kolsteren |first4=Patrick |last5=Spanoghe |first5=Pieter |date=November 11, 2021 |title=Exposure of infants to organochlorine pesticides from breast milk consumption in southwestern Ethiopia |journal=Scientific Reports |volume=11 |issue=1 |page=22053 |doi=10.1038/s41598-021-01656-x |pmid=34764390 |pmc=8585979 |bibcode=2021NatSR..1122053M }}</ref>

== See also ==
*[[Breastmilk storage and handling]]
*[[Blocked milk duct]]
*[[Breastfeeding in public]]
*[[Breast milk jewelry]]
*[[Human milk banking in North America]]
*[[La Leche League International]]
*[[Lactation room]]
*[[Lactivism]]
*[[Mary Rose Tully]]

==References==
{{Reflist}}

== Further reading ==

* {{Cite book |last=Van Esterik |first=Penny |title=Food and Culture: A Reader |publisher=[[Routledge]] |year=2019 |isbn=978-1-138-93057-5 |editor-last=Counihan |editor-first=Carole |edition=4th |location=New York & Oxford |chapter=Breastfeeding as Foodwork |editor-last2=Van Esterik |editor-first2=Penny |editor-last3=Julier |editor-first3=Alice P}}

== External links ==
* [https://www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/vaccinations-medications-drugs/prescription-medication-use.html Drug Interactions with Human Milk]
* ''[https://emedicine.medscape.com/article/1835675-overview Human milk and lactation]'' by Carol L. Wagner (Overview article, eMedicine, December 14, 2010)
* [https://web.archive.org/web/20101023071139/http://www.unu.edu/unupress/food/8F174e/8F174E04.htm United Nations University Centre – Constituents of human milk] – including comparison of human and cow's milk ones
* [https://web.archive.org/web/20070120085511/http://www.aap.org/healthtopics/breastfeeding.cfm Children's Health Topics: Breastfeeding]
* [https://web.archive.org/web/20140821103225/http://www.vegetarian.org.uk/campaigns/whitelies/wlreport05.shtml A comparison between human milk and cow's milk] and [https://web.archive.org/web/20140811224245/http://www.vegetarian.org.uk/campaigns/whitelies/wlreport06.shtml The composition of cow's milk]
* Meigs, EB (August 30, 1913) [http://www.jbc.org/content/16/2/147.full.pdf The comparative composition of human milk and of cow's milk], J.Biol.Chem 147–168

{{Breastfeeding}}
{{Infants and their care}}
{{Milk by provenance}}
{{Nursing}}
{{Authority control}}

[[Category:Breast milk| ]]
[[Category:Breast]]
[[Category:Breastfeeding]]
[[Category:Body fluids]]
[[Category:Neonatology]]
[[Category:Midwifery]]
[[Category:Milk by animal]]
[[Category:Immunology]]
[[Category:Babycare]]