Kourtney Kardashian Barker isn’t the first to drink breast milk – but we know surprisingly little about its adult health benefits

“I just pounded a glass of breast milk because I feel sick ???? goodnight!” wrote Kourtney Kardashian Barker on an Instagram story to her 224 million followers in April 2024.

Her comment attracted shock, horror and disgust from many social media users, but it’s not the first time Kardashian Barker has used her milk as medicine. In 2013, she applied her breast milk to her sister Kim Kardashian’s leg in an effort to heal a patch of psoriasis.

The Kardashians are usually trendsetters. But by drinking her own breast milk, the eldest Kardashian sister helped promote a health trend already steeped in centuries of medical history.

After giving birth to Rocky, her child with Blink 182 drummer Travis Barker, Kourtney clearly wanted to put her extra breast milk to good use again. But is there any evidence that human milk is an effective remedy for illness?

The production of milk defines mammals. Every mammal produces milk which has been tailored to their offspring over millennia of evolution. As well as providing all the energy and nutrients needed for growth of newborns, human milk packs a punch of extra components that support the development of the immune system.

The World Health Organization recommends exclusive breastfeeding for the first six months of life. Once solid food is introduced, it is recommended that breastfeeding continues to two years of age and beyond. One thing that is not recommended by any health organisation is adult consumption of human milk.

History of human milk as medicine

Historically, there have been reports of human milk as a treatment for a range of illnesses. The physician and naturalist Thomas Muffet claimed in 1584 that human milk was good “not only for young and tender infants, but also for men and women of riper years, fallen by age or by sickness into compositions”.

In the 18th century it was also used to feed adults ill with consumption (now known as pulmonary tuberculosis). Many healers of the day also recommended treating eye infections with human milk, which was known as “whitened blood”.

We know that human milk contains many components which can be effective as antimicrobials – lactoferrin and antimicrobial peptides, for example. However, there is no robust evidence to suggest that that human milk can be used to treat illness and infections in adults.

Bodybuilders think breast is best

Human milk is also used by some bodybuilders to lose fat and bulk up. This has created an online marketplace allowing easy access to breast milk.

The 2020 Netflix series (Un)Well featured an episode focused on the safety and ethics of breast milk for bodybuilding. The practice was found to be both expensive and dangerously unregulated.

As with any private and unregulated market, there are risks, the primary one in this case being microbiological contamination. This can come through the expression process and is typically associated with handling and cleanliness of pumps and tubing.

This can be easily minimised by following health authority guidelines (such as from the UK’s NHS). Contamination of expressed milk can also be made worse through improper storage, such as more than a few hours at room temperature or a few days in the refrigerator, before freezing at around -20°C.

Unless they have a well equipped microbiological testing laboratory at home, people who buy human milk have no way of testing the safety of their purchase. Researchers at Nationwide Children’s Hospital in the US have shown that human milk purchased over informal networks has shown concerningly high levels of microbiological contamination. One in ten samples were also found to have added formula milk or cow’s milk.

Lack of research into potential benefits

The evidence does not exist that the use of human milk is beneficial to treat illnesses in adults. This does not, however, mean that it will not come. Considering human milk feeds most of the world’s population for the first six months of their life, it is a surprisingly understudied area.

Researchers have shown preliminary evidence that specific components of human milk could have antimicrobial activity against pathogens that infect adults. This may provide novel ways of treating infections in the future, but the work will require time and resources to reach this point.

Even though there is no established benefit of consuming human milk for adults, there is plenty of evidence of its benefit for newborns. For those who are unable to receive their mother’s own milk, WHO recommends the provision of donor human milk processed by regulated milk banks to ensure its safety. This will normally involve the screening of the donor and donated milk, similarly to blood donations, and pasteurisation to inactivate viruses and other microorganisms.

Kourtney Kardashian Barker may find that she has a surplus of expressed milk again in the future. If she does, there are many human milk banks in her native California that would welcome her donation. This would benefit vulnerable newborns in a way that is very much supported by evidence.

Simon Cameron receives funding from UK Research and Innovation for work related to human milk microbiology and composition.