Hair supplements: what the evidence supports, and what it does not

Hair supplements: what the evidence supports, and what it does not

On a healthy scalp about nine per cent of follicles are resting at any given moment, and somewhere between 100 and 150 hairs leave the head every day without anything being wrong. Those figures come from a 2023 review in the Journal of Clinical Medicine, and they are the background noise against which every hair supplement is judged.

We sell one. That is worth saying first, because what follows is an audit of the category we sell in, and in several places the honest answer is that the evidence is thinner than the marketing.

The short version

• A supplement never reaches the hair fibre, only the living follicle, and the follicle runs on a slow clock. In telogen effluvium the trigger sits roughly three months before the shedding starts, and growth can take up to six months to restart. Three months is the shortest honest observation window, and six is better.

• The objection that matters most: biotin does carry an authorised EU claim about hair, but all 18 cases reported in the literature had an underlying deficiency or an inherited condition. The adequate intake is 30 micrograms a day. Hair products carrying 5,000 or 10,000 micrograms rest on a claim that is satisfied at a fraction of that dose, and high intakes interfere with troponin and thyroid function tests.

• Hair Beautification contains 300 mg of Keranat millet seed extract per daily dose, the dose the manufacturer specifies, plus 50 µg biotin, zinc and vitamin B6 at reference intake levels rather than at megadose. Biotin and zinc contribute to the maintenance of normal hair. For millet extract no health claim may be made, because the EU botanical claims have still not been adopted.

Health Royals Hair Beautification, hair supplement with Keranat millet extract, biotin, zinc and vitamin B6

What is actually in our jar

Hair Beautification contains 300 mg of Keranat millet seed extract per daily dose. That is the dose the manufacturer specifies and the one tested in the randomised trial of 65 women over 12 weeks, in which telogen density fell significantly while anagen density rose just as much in the placebo group. The trial is manufacturer funded and has no independent replication, and the same material is sold at the same dose by several other brands. Alongside it sit 50 µg biotin, zinc and vitamin B6 at reference intake levels rather than at megadose. Biotin and zinc contribute to the maintenance of normal hair, zinc contributes to normal protein synthesis and vitamin B6 contributes to normal cysteine synthesis. For millet extract no health claim may be made, and we make none.

See Hair Beautification

What can a hair supplement actually influence?

Only the living follicle, and only slowly.

The visible hair is dead keratin with no blood supply and no metabolism, which we have written about in more detail in the biology of the hair fibre. Nothing swallowed reaches it. What nutrition can reach is the follicle in the skin, and the follicle runs on a slow clock.

The same review puts anagen, the growth phase, at about two to eight years for scalp hair, catagen at about two weeks and telogen, the resting phase, at about two to three months.

That clock explains the most misused promise in the category. In telogen effluvium, the diffuse shedding that follows illness, surgery, childbirth or a crash diet, the StatPearls review places the trigger roughly three months before the shedding starts, with a range of one to six months, and notes that hair growth may take up to six months to restart. The follicle is already three months behind the event that changed it.

A product promising a visible difference in four weeks is promising something the tissue cannot deliver. Three months is the minimum honest observation window, and six is better.

What is biotin good for?

Biotin is a coenzyme for the carboxylase enzymes that run fat and amino acid metabolism, and in the EU it carries one authorised claim about hair.

The authorised wording, from Commission Regulation 432/2012, is exactly this: "Biotin contributes to the maintenance of normal hair". That is a nutrient function claim: the vitamin has a role in keeping normal hair normal. It is not evidence that additional biotin makes hair grow in a person who already has enough, and the two are constantly conflated on labels.

The evidence for that second, unstated claim is weak. A 2017 review by Patel, Swink and Castelo-Soccio in Skin Appendage Disorders searched the literature for biotin used for hair and nail complaints and found 18 reported cases. Every one of them had an underlying deficiency or an inherited condition such as biotinidase deficiency. The authors concluded that there is a lack of sufficient evidence for supplementation in healthy individuals. A 2019 review in Dermatology and Therapy is blunter still, finding that neither vitamin E nor biotin supplementation is supported by the literature for androgenetic alopecia or telogen effluvium.

Deficiency itself is uncommon. The US Office of Dietary Supplements notes that severe biotin deficiency in healthy people eating a normal mixed diet has never been reported.

How much biotin per day is reasonable?

The adequate intake for adults is 30 micrograms a day. Hair products routinely contain 5,000 or 10,000 micrograms, which is 170 to 330 times that figure, on the strength of a claim that is satisfied at a fraction of the dose.

High intakes are not merely pointless. They are a laboratory problem. Biotin interferes with the biotin and streptavidin chemistry used in many immunoassays, and the US Food and Drug Administration keeps a public list of troponin tests that have not addressed the risk, warning that interference can produce falsely low troponin results. The Office of Dietary Supplements records that a patient with a high intake of supplemental biotin died after a troponin test returned a falsely low result, and that a single 10 mg dose has interfered with thyroid function tests taken within 24 hours. Thyroid disease is itself a common cause of hair shedding, so the interference lands precisely where it does most damage.

Sellers almost never mention this. If you take biotin at any dose above food levels, tell whoever draws your blood.

Hair vitamins: which B vitamin is good for hair?

Of all the B vitamins, only biotin, vitamin B7, carries an authorised EU claim that mentions hair at all.

Vitamin B6, B12, folate, niacin and riboflavin all have authorised claims, and several of them are about metabolism, tiredness or red blood cell formation. None of them is about hair. A B complex sold as a hair vitamin is resting on one ingredient plus a general metabolic story, and the label rarely makes that distinction visible. We have written separately about what biotin does in metabolism.

Two other minerals do carry hair wordings. Zinc has "Zinc contributes to the maintenance of normal hair" and "Zinc contributes to the maintenance of normal nails". Selenium has "Selenium contributes to the maintenance of normal hair" and "Selenium contributes to the maintenance of normal nails". Vitamin D, despite appearing in almost every hair formula sold, has no authorised claim about hair anywhere in the register.

Iron and ferritin: when is a blood test the right next step?

When shedding is diffuse and persistent, particularly in menstruating women, ferritin is the one number worth measuring before buying anything at all.

A 2022 systematic review and meta analysis in Skin Appendage Disorders pooled 36 studies covering 10,029 participants and found that women with nonscarring alopecia had significantly lower ferritin values than controls, a mean difference of 18.51 ng/dL, with roughly 21 per cent of women with hair loss showing ferritin at or below 10 to 15 ng/dL.

An association is not causation, and the review does not establish that iron pills regrow hair. What it does establish is that ferritin is worth measuring. Swedish primary care guidance on hair loss lists ferritin and TSH among the tests to consider, which is the right sequence: measure, then decide.

Iron bought blind is a poor idea. It accumulates, the authorised claims for it concern oxygen transport and the reduction of tiredness and fatigue rather than hair, and unnecessary supplementation carries real risk. This is a doctor and a blood sample, not a purchase.

Do skin, hair and nail supplements help brittle nails?

For nails specifically the trials exist, but they are old, small and mostly uncontrolled.

A 2018 review by Lipner and Scher in the Journal of Dermatological Treatment gathered what there is on oral biotin for nail disease. It reports improvements in the firmness, hardness and thickness of brittle nails, and then concludes that larger controlled trials are still needed to establish efficacy and dosing.

The combined skin, hair and nail category also carries a risk that is almost never printed on a label: too much of a trace element damages exactly the tissue it is sold to support. The clinical signs of chronically high selenium intake are hair loss and nail brittleness or loss. In 2008, 201 people in the United States had severe reactions to a liquid supplement that contained 200 times the labelled amount of selenium. The tolerable upper intake level for adults is 400 micrograms a day. Excess vitamin A is also a recognised trigger of telogen effluvium.

What do the studies on millet seed extract show?

One randomised trial in 65 women, published by authors connected to the ingredient's manufacturer, with no independent replication.

Our own hair formula contains 300 mg of Keranat, a millet seed extract made by Robertet in Grasse, a house founded in 1850. The material is miliacin, a triterpenoid from Panicum miliaceum, encapsulated in polar lipids from wheat, and we have described the ingredient in more detail in our note on the millet complex.

The pivotal human study, published in the Journal of Cosmetic Dermatology in 2019, was randomised, double blind and placebo controlled in 65 non menopausal women with telogen effluvium over 12 weeks. Telogen density fell significantly in the supplemented group. Anagen density rose in both groups, with no significant difference between them. Scalp dryness and hair brightness improved more in the supplemented group.

Now the parts a seller would rather leave out. Sixty five participants is a small trial. Anagen density, arguably the outcome most people care about, did not separate from placebo. The authors include people affiliated with the material's manufacturer, which makes this manufacturer funded research on a proprietary ingredient, and that is a weaker form of evidence than independent replication. No independent replication exists. Robertet's own summary of its scientific studies reports a 50 per cent average reduction after 12 weeks by phototrichogram, and that number comes from the manufacturer, not from a third party.

Two more things. Under EU rules, health claims for botanical substances were split off from the rest of the Article 13 list and have still not been adopted, so no health claim may be made for millet extract at all. And 300 mg is simply the dose the manufacturer specifies. Several other brands sell the same material at the same dose, so it is not exclusive to us, and we would rather say so.

What does the evidence not show?

It does not show that any food supplement can do anything about hereditary hair loss.

Androgenetic alopecia affects roughly half of men and women over a lifetime. It runs on dihydrotestosterone and 5 alpha reductase activity at the follicle, which shortens anagen and drives follicular miniaturisation, and its established treatments are topical minoxidil and oral finasteride. Those are medicines. A food supplement is not, and no formulation of vitamins and plant extracts changes androgen signalling in a follicle.

EU law reflects this. A food may not state or imply that it prevents, treats or cures any condition, which means no supplement, ours included, may be described as reducing hair loss. Where a brand says otherwise, it is breaking the rule, not reporting a finding.

The wider pattern is consistent: correcting a shortage helps, adding more on top of sufficiency mostly does not. The 2019 Dermatology and Therapy review finds insufficient data to recommend zinc supplementation outside deficiency, mixed results for vitamin D in female pattern hair loss and telogen effluvium, and no case for selenium at all.

Hair loss that is sudden, patchy, accompanied by scalp symptoms or scarring, or that keeps going for more than six months, belongs with a doctor and not with a supplement shelf.

What is reasonable to do in practice?

Start by ruling out what a supplement cannot touch: thyroid function, iron status, a recent illness or delivery, a new medicine, a very restricted diet. Ask for ferritin and TSH rather than guessing.

If you then take something, take it for at least three months before forming a view, and take a photograph in the same light at the start so you are comparing something other than memory. Check the total biotin, selenium, zinc and vitamin A across every product you take. Expect maintenance rather than transformation, because that is what the authorised claims actually describe.

Our own hair page sets out how we think about the category, and Hair Beautification is the formula this article has been auditing: 300 mg of Keranat, with biotin, vitamin B6 and zinc at reference intake levels rather than at megadose. It is a food supplement, which is a smaller thing than most of the category pretends.

Further reading

Frequently asked questions

Do hair supplements work for hair loss?
Not for hereditary hair loss. Androgenetic alopecia runs on dihydrotestosterone and 5 alpha reductase activity at the follicle, and its established treatments are medicines. Nor may a food supplement be described as reducing hair loss, because a food may not be said to prevent, treat or cure any condition. Where a brand says otherwise, it is breaking the rule.

How much biotin do you need for hair?
The adequate intake for adults is 30 micrograms a day, and severe biotin deficiency has never been reported in healthy people eating a normal mixed diet. The 5,000 and 10,000 microgram doses common in hair products are 170 to 330 times that level, on the strength of a claim satisfied far below it. High intakes are also a laboratory problem, so tell whoever draws your blood.

How long before you see any difference?
At least three months, and six is better. Telogen lasts about two to three months, and in telogen effluvium the trigger sits roughly three months before the shedding starts. A product promising a visible difference in four weeks is promising something the tissue cannot deliver. Take a photograph in the same light at the start, so you are comparing something other than memory.

Should I take iron if my hair is shedding?
Not without measuring first. A 2022 meta-analysis of 36 studies and 10,029 participants found that women with nonscarring alopecia had significantly lower ferritin values than controls, but an association is not causation and the review does not show that iron pills regrow hair. Swedish primary care guidance lists ferritin and TSH among the tests to consider. Iron accumulates, so this is a blood sample and a doctor, not a purchase.

Can a supplement make shedding worse?
Yes, and it is almost never printed on a label. The clinical signs of chronically high selenium intake are hair loss and brittle nails, and the tolerable upper intake level for adults is 400 micrograms a day. Excess vitamin A is also a recognised trigger of telogen effluvium. Add up the biotin, selenium, zinc and vitamin A across every product you take at once.

What is Keranat, and how good is the trial behind it?
Keranat is a millet seed extract from Robertet in Grasse, in which the active constituent is miliacin encapsulated in polar lipids. The pivotal trial was randomised, double blind and placebo controlled in 65 non menopausal women over 12 weeks. Telogen density fell significantly, but anagen density, arguably the outcome most people care about, did not separate from placebo. The authors include people affiliated with the manufacturer, and no independent replication exists.

Sources