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Breast milk for adults: we went looking for the evidence

Bodybuilders buy human milk. So do people getting over an illness, people with gut trouble, and people losing their hair. This page is what we found when we checked those claims one at a time – and since we are the ones selling it, read the paragraph under the summary as well.

One disclosure before anything else, because it decides how you should read the rest. We are a marketplace for human milk. We make money when milk sells, including to you. A page that told adult buyers what they wanted to hear would be the profitable page to write. We are writing the deflationary one because the alternative is selling you a promise we cannot keep, and because the mothers we want listing here would not thank us for a website that made claims about their milk that nobody can support.

Who buys it, and why we are not going to be odd about it

The fitness lane is the best known: men buying frozen milk in bulk for training, usually described in terms of recovery and "natural" nutrition. Behind it sits a quieter set of buyers – people in chemotherapy, people recovering from gut surgery, people with long-running digestive conditions, and people who read something once about immunity and thought it was worth a try. Some are hopeful. Some are desperate. Almost none of them want a lecture. If the idea itself still feels strange, that reaction has a history and we wrote it up separately: why buying breast milk feels weird.

Our position is simple and it is not going to change: nothing in food law turns on who drinks it, and we do not ask buyers to justify themselves. Selling human milk is legal in the UK and the US, and the legality does not acquire an asterisk when the buyer is an adult.

Two things do apply to you as an adult buyer. The first is the audience setting: every seller decides whether her listing is open to families only or open to everyone, and the setting is enforced at the point of contact. A listing closed to you is not a judgement we passed – it is a mother's own boundary, and she owes nobody an explanation for it. The second is the conduct rule, which is short: sellers are here to sell food. Contact that treats them as anything else ends the account.

And one consumer warning, from the literature rather than from us. The 2015 review in the Journal of the Royal Society of Medicine that first put adult buying under a microscope noted sellers charging adult buyers as much as four times the price families pay. Know the ordinary rate before you make an offer: peer-sold milk runs $1.50 to $4.50 an ounce in the US, and roughly £1.20 to £3.50 per fl oz in the UK. The pricing page shows what moves a listing up or down that range.

What is actually in it

Start with the food, since most of the claims collapse here without any further argument. Mature human milk averages out like this, next to the bottle of whole milk in your fridge:

Human milk figures are the Australian Breastfeeding Association's averages for mature milk; the cow's milk column is a typical UK carton label, which you can check on your own doorstep. Individual mothers vary, and so does one woman across a single feed.

Read that table as a design brief and it makes perfect sense: a low-protein, high-sugar, moderate-fat food built for a small human who is growing a brain and cannot chew. Read it as sports nutrition and it is upside down.

Two consequences worth stating out loud. Human milk has about a third of the protein of cow's milk, one of the lowest protein contents of any mammal's milk. And it has considerably more lactose. If you avoid dairy because lactose disagrees with you, human milk is the wrong direction entirely. The one dairy problem it genuinely sidesteps is the protein one, which is a different condition with a different mechanism, explained on our page about human milk against animal milk.

The gym: the arithmetic is the whole argument

A 100 ounce order is three litres of milk. At peer prices that is $150 to $450, or £120 to £350, plus frozen postage. Inside those three litres sit roughly 36 grams of protein.

Two pints of supermarket whole milk – 1.1 litres, a couple of pounds at the till – carry slightly more protein than that. Whey powder, the staple of every gym bag in the country, is cow's milk protein with the water taken out, and one tub carries more than the freezer full. The three litres also bring about 2,100 calories, most of them lactose and fat, which is a costly way to eat a day's energy.

The usual reply is that the point was never the protein: it is the growth factors, the hormones, the living components. Those are present, and they are proteins too. A newborn's gut handles some intact proteins in a way an adult's does not; whatever survives your stomach acid then meets the same enzymes that take apart a steak. There is no trial showing any of it reaching an adult muscle. The JRSM review put it plainly: the purported benefits "do not stand up clinically", and milk bought online is "not optimal for adult nutrition or in the treatment of disease".

If a training buyer wants to keep buying with all of that in view, that is their business and their money, and sellers here are welcome to serve them. We would rather that trade ran on a clear head than on an advertisement we wrote.

Hair loss: missing strands of evidence

This one is short, because nobody has run the study. That is a gap in the literature, not a result: no trial has looked, so none has failed. We looked for clinical trials of human milk for hair loss – swallowed, or massaged into the scalp – and found none. What exists is a genre of supplement-blog articles citing one another, usually pivoting to a product by the fourth paragraph. Milk on your scalp will not hurt you. It is a wash, it is not a treatment, and at peer prices it is the most expensive conditioner ever sold.

Hair loss does have treatments with real evidence behind them, and more usefully it has causes worth identifying: thyroid trouble, iron, medication, and several patterns a GP can tell apart quickly. The NHS page on hair loss is the honest starting point, and it says to see a GP before a commercial hair clinic. We are a milk marketplace; that is as far as our competence reaches.

Immunity and "general health": the antibodies are real, and they are not going where you think

Human milk is genuinely full of immune machinery. Secretory IgA, lactoferrin, lysozyme, live cells, oligosaccharides: the list is long and the science behind it is good. The leap comes next, when people assume that swallowing those things transfers them to your immune system.

Secretory IgA is built to survive digestion, which is exactly why it works in the gut. It coats the surfaces it lands on and interferes with bacteria and viruses sticking to the gut wall. It does not cross into your bloodstream and top up your defences. Meanwhile your own intestine is already secreting three to five grams of IgA every day, making it the most abundant antibody your body produces. A glassful of human milk carries a small fraction of a gram into a system that manufactures grams of the stuff daily, all of it tuned to the bugs in your own household.

Lactoferrin is the other component people name, and it is worth knowing that you can already buy it: it is sold as a supplement, made from cow's milk, standardised and cheap. That pattern repeats through this whole subject, and it is the most useful thing on this page.

Cancer: real science, pointing somewhere else entirely

This claim deserves respect, because underneath it sits genuine research. In 1995 a group in Lund led by Catharina Svanborg found that a component of human milk killed tumour cells while leaving healthy ones alone. They named it HAMLET, for Human Alpha-lactalbumin Made LEthal to Tumour cells. It is a complex of alpha-lactalbumin, a milk protein, with oleic acid, a fatty acid. Both halves are required.

Then look at how it reaches a patient. The version now in trials, alpha1-oleate, is built from a 39-amino-acid fragment of that protein, mixed with sodium oleate at a set molar ratio in a laboratory. In the bladder cancer studies it was instilled directly into the bladder through a catheter, 30 ml at a time, on six occasions. The published results are encouraging: tumour cells shed into the urine, complete or partial responses in most treated tumours at the higher dose, few side effects beyond local irritation.

None of that describes a glass of milk. The complex does not exist in the bottle; it is made by unfolding a protein and binding a fatty acid to it under conditions a kitchen cannot produce, and it was delivered to a bladder instead of a stomach. A page that cited this research as a reason to buy milk from a stranger would be misreading it in the most basic way available.

The harder thing to say, and the reason this section is not shorter: people with cancer are among the most frequent adult buyers, and they are the readers with the most to lose from unscreened raw milk. Chemotherapy is not the moment for a food-safety gamble. Whatever you decide, tell your oncology team – they will have seen the question before, and they need to know what you are drinking.

The gut and the microbiome: the claim with real adult trials behind it

Human milk oligosaccharides are the most interesting thing in milk that nobody outside the field had heard of ten years ago. They are sugars the baby cannot digest at all. They are there to feed particular gut bacteria, and they have become the one part of this story with actual adult trials attached.

This is also the one section of this page where the honest answer is that something real happens. In a two-week trial, 100 healthy adults took purified 2'-fucosyllactose and lacto-N-neotetraose at five, ten or twenty grams a day. Bifidobacteria rose substantially, Firmicutes and Proteobacteria fell, and roughly three quarters of the participants responded. A six-week trial in 89 people aged sixty and over, at one gram and five grams a day, raised Bifidobacterium again in the higher-dose group. A crossover trial in ulcerative colitis found no clear effect on the standard disease measures, with some improvement in how patients rated their own control of it. Enriching an adult microbiome with these sugars is a genuine finding, and anyone who tells you they do nothing outside infancy is behind the evidence.

Then comes the arithmetic, and it is as unforgiving here as it was about the gym. The five-gram arm is where most of those changes reached significance. Mature milk carries somewhere around 1.6 to 2 grams of 2'-fucosyllactose per litre, so five grams a day means drinking two and a half to three litres of milk, every day, for six weeks – £100 to £355 a day at the going rate, or $125 to $455. The two-week safety study went as high as twenty grams a day, which is ten litres or more. Even the low-dose arm, one gram, is about half a litre of milk daily, and that is the arm where the least happened.

There is also a lottery nobody mentions in the listings. Whether a woman makes 2'-fucosyllactose at all is decided by a gene called FUT2. Milk from women with both copies inactivated contains zero or only traces of it, and inactivating variants turn up in about one person in five in the populations where they have been counted. So roughly one seller in five is offering milk with essentially none of this molecule in it. She does not know that, you cannot see it, and no honest listing can tell you either way without a laboratory.

And the milk most likely to be for sale is the milk with the least of it left. Oligosaccharide content falls as lactation goes on – about 17.7 grams per litre in colostrum, 13.3 in transitional milk, 11.3 in mature milk – with 2'-fucosyllactose itself dropping from around 3.2 grams per litre early to 1.6 in late milk. A freezer stash is by definition milk from further along, often months along. The thing the claim rests on is the thing that thins out first.

The 2'-fucosyllactose in those trials was made in a factory by enzymatic synthesis, and it is worth being careful about what that does and does not settle. It settles the dose: a sachet is measured, identical every time, with no donor, no cold chain and no secretor lottery. What it does not settle is whether the molecule carries the effect on its own. The trials used two oligosaccharides, 2'-fucosyllactose and lacto-N-neotetraose. Mature human milk carries more than a hundred and fifty distinct oligosaccharide structures, alongside the fat globule membrane, the live cells and the enzymes that come with them.

That distinction has a history worth knowing, and it does not run the way the supplement aisle would like. Diets rich in carotenoid vegetables looked protective against lung cancer for years; when the active molecule was isolated and given as beta-carotene in large trials, the supplement raised lung cancer rates in smokers. Isolating the interesting compound is a reasonable first move and it is not the same as reproducing the food. Sometimes the matrix is the thing, and we do not yet know which case this is.

What you are actually taking on

Milk from a peer seller is a raw food. It has not been pasteurised and the donor has not been screened, unless she chose to do both and can show you. Milk banks screen donors for HIV, HTLV, hepatitis B, hepatitis C and syphilis and pasteurise every batch, and that is the list the JRSM review repeats for adult buyers, adding cytomegalovirus. Those are unlikely in any one seller and they are not zero across a market.

Bacteria are the everyday risk. The study everyone quotes bought 101 samples from a US milk-sharing site, shipped to a rented mailbox with no coolant and no seller accountability: 74% carried Gram-negative bacteria or high total aerobic counts. A follow-up found around one sample in ten had cow's milk mixed in, which tells you what an anonymous seller does when nobody can find them afterwards. Our reading of those studies is the same for adults as for families, and we set it out on the page about that bacteria study: they measured a venue, and the venue is fixable.

Two warnings specific to adult buyers. If you are immunosuppressed – chemotherapy, transplant medication, advanced HIV, a condition your consultant has described that way – you are both the likeliest buyer on this page and the person least able to absorb an infection. This is a decision for your medical team, and we would rather lose the sale. And if lactose is your reason for avoiding dairy, see the table above: you would be increasing your dose.

What actually stands between you and a bad batch?

Most people arrive with a ranking already in their head: supplements are the sensible option, formula is industrial, and raw human milk from a stranger is the reckless one. It is worth asking what that ranking is actually built on, because "regulated" and "safe" are not the same word, and the three things an adult buyer might compare fail in completely different directions.

The column that surprises people is the last one. In the US, the Dietary Supplement Health and Education Act of 1994 put supplements outside the approval process that covers drugs and infant formula: the manufacturer decides its own product is safe, puts it on sale, and the regulator may act afterwards if something goes wrong. In practice "afterwards" is doing enormous work – there are something like a hundred thousand supplement products on sale, and enforcement reaches a rounding error of them. The FDA’s own database of products found to contain undeclared drug ingredients – sibutramine, sildenafil, anabolic steroids – runs to hundreds of entries, and it is concentrated in exactly three categories: weight loss, sexual enhancement and bodybuilding. If you came to this page from the gym, that is your aisle.

It is also why independent testers keep finding things. Tamara Rubin's Lead Safe Mama has spent years publishing X-ray fluorescence results on consumer products, supplements among them, and the reason that work has an audience is that nobody official is doing it. Read those results for what they are: XRF measures what is present in an item, not the dose that reaches a person, and she is an independent advocate rather than a laboratory. It is a reason to ask questions, not a number to quote.

The honest summary is that these things fail in opposite directions, and only one of the two failures is yours to manage. Milk’s risk is bacterial, and it is visible and fixable: buy from a named seller, ask for her screening, insist it arrives frozen solid, and you have addressed nearly all of it. A supplement’s risk is that the label is the only thing you know, and the label can be false – no amount of care at your end can inspect for that. We are not going to pretend peer-sold milk is a regulated product; it is not approved, not batch-tested and not inspected by anybody, and the pathogen risk above is real. But one ingredient from a named woman with a record to lose is a different kind of unknown from twelve ingredients from an unnamed factory, and the ranking most people walk in with has those two the wrong way round.

If you are going ahead anyway

Plenty of readers will, and a page that shrugged at that point would be no use to anybody. The controls that matter are the same ones families use, and they work:

• Buy from a named seller with a track record, never from an anonymous advert. Every study on this page measured anonymity as much as milk. Our guide to buying safely is the long version.
• Ask about screening. Plenty of sellers hold recent results, and the donor screening page tells you what a full panel covers and what it costs, so you know what you are asking for.
• Insist on the cold chain. Frozen, insulated, next-day, arriving still solid. How milk should travel is worth reading before you agree a delivery.
• Heat it. Flash-heating on a hob kills the great majority of what might be in there, and our home pasteurising guide gives the method along with its honest limit: some staph toxins survive heat, so heat is the second line and an honest seller with a working freezer is the first.
• Know the price. $1.50 to $4.50 an ounce, £1.20 to £3.50 per fl oz. If you are quoted four times that because of who you are, you are being charged an adult tax, and you should say so and move on.

Common questions