Do vitamins for hair really work?

What are hair vitamins for, and where are the limits?

Which effects are actually documented?

The scalp has around 100’000 hair follicles, and roughly nine hairs out of ten are in full growth at any given moment^[2]. For keratin production — the protein, made of amino acids, that forms the hair structure —, the follicle continuously consumes proteins, vitamins and minerals, delivered by the scalp’s blood supply. These micronutrients play a crucial role in hair health throughout every hair cycle: at the root, cell division is intense, and these cells are among the first to give way when the body lacks something. A deficit can then show in the hair: drier, more brittle, or falling out more.

Yet this “more is better” logic does not hold. A large 2023 review in a leading dermatology journal examined supplements in people with no initial deficiency: the evidence of benefit there is at best modest and of variable quality^[1]. In other words, correcting a real shortfall can help; topping up a body that lacks nothing does not transform a head of hair — and no capsule, pill or tablet is a miracle solution.

Why a supplement isn’t enough if the cause lies elsewhere?

The most common thinning — androgenetic alopecia, which thins the top of the head with age, in men as in women — is largely hereditary and hormonal: no vitamin makes it disappear. Likewise, patchy hair loss (alopecia areata, autoimmune in origin) calls for specialist medical advice. Finally, an overly restrictive slimming diet is a documented cause of diffuse hair loss, sometimes two to five months after rapid weight loss^[2]. Before looking for the right capsule, you therefore have to identify the real cause.

Which nutrients really matter?

Iron and vitamin D: the two to get tested

Iron deficiency is the most widespread nutritional deficiency in the world, and it is closely linked to temporary diffuse hair loss, telogen effluvium^[2]. Periods, pregnancy and the post-pregnancy period are the main drivers in women. As for vitamin D, several large recent reviews find that people affected by hair loss have, on average, lower levels than others, with the link clearest for alopecia areata and female thinning^[5][6]. Note: this is an association, not proof that supplementation makes hair grow back.

Here is what the literature shows for each frequently cited nutrient — each fulfils a function in the body, more or less linked to hair. The “authorised claim” column gives the only wording that European and Swiss law allows on a product: a good reality check.

Biotin, zinc, selenium: what the label says — and doesn’t

Biotin is the star ingredient of “hair, skin, nails” supplements. Yet the only trial run under good conditions, with a placebo group, found no difference between biotin and placebo on growth^[4]. All documented improvements concerned people with a genuine biotin deficiency or a particular illness^[3]. And in a person who eats normally, this type of vitamin deficiency has never even been described^[2].

Antioxidants and diet: the real foundation

It’s often said that antioxidants such as vitamins C and E “protect” the follicle and help reduce oxidative stress. The idea is plausible, but no clear benefit on hair loss has been demonstrated, and this protection does not replace a proper diet.

Before supplements, the plate. A natural, varied diet covers most of the needs for hair growth. Iron is found in meat and offal such as liver (animal sources), but also in pulses such as lentils and in green vegetables like spinach (plant sources, useful on a vegan diet, to be paired with a source of vitamin C such as bell peppers that helps absorb it). Zinc, for its part, is found in meat, fish, seafood, nuts and seeds such as almonds and pumpkin seeds, which also contain it; proteins, the raw material of keratin, come from eggs, fish and pulses. Oily fish and vegetable oils provide omega-3 fatty acids, as part of a balanced diet, and brewer’s yeast is rich in B vitamins (folic acid/folate, pantothenic acid). Eating well remains the foundation of healthy hair growth; vitamins in capsules are only a support, not a substitute.

Deficiencies and hair loss: where to start?

The right move: a blood test before the capsules

When hair loss is diffuse, two nutritional leads deserve a blood test before any purchase. In a recent study of nearly 2’900 women seeking advice for hair loss, almost half had low iron stores^[7]. In the largest series published on this type of hair loss, ferritin testing is in fact the most common examination and iron supplementation the most prescribed treatment^[8].

1. 1Have your iron stores (ferritin) tested and, depending on the context, vitamin D and the thyroid, on a doctor’s prescription.
2. 2Make sure you eat enough and varied food; avoid very restrictive diets that trigger hair loss.
3. 3See a healthcare professional (dermatologist or doctor) if the hair loss is sudden, heavy or patchy, to tell temporary loss from hereditary thinning.

Women, periods, pregnancy — and the case of diabetes

Iron is the number-one cause in women, because periods and pregnancy deplete the stores: post-partum hair loss, common after a baby arrives, is the best-known example. Many doctors consider a low ferritin, below about 30 to 40 micrograms per litre, a deficit to correct; below this threshold, the proportion of shedding hair increases^[9]. Hair loss due to a deficiency is corrected by treating the shortfall, but that is not always enough, which is why it’s worth going through a doctor. As for diabetes, there is no specific “hair” vitamin: certain treatments or situations can come with a vitamin deficiency (vitamin B12, for example), to be investigated with a blood test; self-medication is not advisable, and a healthy lifestyle — varied diet, sleep, exercise — remains the best foundation.

Fine hair and supplements: avoiding the traps

Fine hair, falling hair: telling the cause apart

“Which vitamin to thicken my hair?” — or “what are the best vitamins for hair?” — is probably the most-asked question, and the answer depends first on what we’re talking about. Diffuse, temporary hair loss (after childbirth, a shock, a diet, an illness or against a background of deficiency) often recovers once the cause is removed. Progressive thinning that thins out the crown, on the other hand, is largely hereditary and hormonal: no vitamin makes it disappear. The best approach therefore starts with a diagnosis, not a supplement. Neither a shampoo, nor a care capsule, nor a “hair and nails” course replaces this step.

Reading a label without being fooled

The beauty and cosmetics aisle overflows with hair dietary supplements and “hair loss vitamins”, often marketed as vitamins for hair growth or against hair loss. Yet on a food supplement, only authorised health claims may be used. For hair, only three ingredients are entitled to one, with precise wording: biotin, zinc and selenium “contribute to the maintenance of normal hair”; copper “contributes to normal hair pigmentation”^[10]. Promises of “essential vitamins to boost growth”, of “anti-hair-loss” products, or of formulas that “strengthen” and “promote” beautiful hair go beyond what science and the law allow. An advertising authority has already sanctioned hair supplement brands whose slogans exaggerated the permitted claims^[10].

• !“Makes hair grow back” or “stops hair loss”: not authorised and not demonstrated.
• !“Guaranteed results in X days” or “the secret against baldness”: misleading.
• !Hair claims for vitamin E, silicon or vitamin B6: not authorised.

Frequently asked questions