Which vitamins your hair actually needs
Only the vitamins and minerals you are demonstrably short of. Beyond that there is no good evidence that supplements make hair thicker, faster or glossier.
That is not the message of the hair vitamin shelf, and it is the message of the literature. I write this as a hairdresser rather than a doctor, so everything below points back to medical sources.
The practical order is simple: your doctor first, supplement second. The other way round costs money and sometimes your hair.
Because here is the part almost never printed on the packaging: with some nutrients, too much actively causes hair loss.
What hair vitamins are
Hair vitamins are food supplements rather than medicines, and that difference decides everything. It decides the standards they must meet.
Most contain a combination of biotin, zinc, selenium, vitamin C, iron and sometimes collagen. The dosage is often far above the daily requirement.
The American Academy of Dermatology warns that hair growth supplements are not regulated and can do more harm than good. It notes that the regulator does not approve supplements for safety and effectiveness before they reach the market.
That same body describes the effectiveness of biotin, collagen and probiotics as often inconsistent or unreliable. It advises a blood test first, to see whether there is a deficiency at all.
That is the core of this article in one sentence. The question is not which supplement, but whether you need one.
Why only a deficiency counts
Your body does not use a surplus, it stores or excretes it. That explains why topping up without a deficiency achieves nothing.
A comprehensive review of the role of vitamins and minerals in hair loss reaches the same conclusion for most nutrients. Supplementation is justified with a demonstrated deficiency, and beyond that the evidence is insufficient.
There is another reason to measure first. A deficiency is usually a symptom of something else, and that something else deserves attention.
Malnutrition is the clearest exception to the whole discussion. Severe protein malnutrition causes hair loss, and you do not solve that with a tablet.
Iron and ferritin
Iron is the best supported nutrition related cause of hair loss. If there is one nutrient the literature has most to say about, it is this one.
Supplementation is justified in patients with a demonstrated deficiency, especially women with diffuse shedding. That is a clearly different statement from everyone losing hair should take iron.
On the threshold there is no consensus. The literature discusses cut offs of thirty, forty and seventy micrograms per litre of ferritin, with thirty micrograms per litre giving ninety two percent sensitivity and ninety eight percent specificity for iron deficiency.
The figures circulating on some websites about ideal ferritin levels of a hundred or higher I could not trace to anything in the professional literature. So I leave them out.
Taking iron without a deficiency is also not harmless. Excess accumulates in the body, which makes this a nutrient to handle through your doctor.
Vitamin D, vitamin C and vitamin E
With vitamin D the answer depends on the type of hair loss. Advertising rarely makes that distinction.
For alopecia areata, the form with round bald patches, the association with low vitamin D is reasonably supported and supplementation is recommended where deficient. That is a condition for a doctor.
For diffuse and hereditary hair loss the results are conflicting. The literature does advise supplementing once a deficiency has been established.
In the Netherlands low vitamin D in winter is not unusual anyway, hair aside. That is a conversation with your doctor rather than a reason to start on hair supplements.
Vitamin C and vitamin E
Vitamin C is an antioxidant that mops up free radicals and helps your body absorb iron from plant foods. That indirect link with an iron shortage is the only reason it is relevant here, because it carries no authorised claim about normal hair.
Vitamin E is on this list for a less comfortable reason. The American Academy of Dermatology names too much vitamin E as one of the nutrients that has been linked to hair loss.
Biotin, the best known and weakest case
Biotin appears on virtually every hair supplement and has the weakest support of them all. That contrast is striking enough to handle separately.
The key publication is a 2017 review in Skin Appendage Disorders. The authors found eighteen reported cases in which biotin helped hair or nails.
In every one of those eighteen the patiënt had an underlying condition: an inherited metabolic disorder, uncombable hair syndrome, brittle nail syndrome or a genuine dietary deficiency. The authors conclude there is insufficient evidence for supplementation in people without low biotin levels.
Biotin deficiency is also rare on a normal diet. Eggs, nuts, seeds and wholegrains supply it comfortably.
Biotin interferes with laboratory tests
This is the reason I would not casually take biotin, and it has nothing to do with your hair. High doses interfere with immunoassays that work on biotin and streptavidin.
That affects thyroid values and the troponin test used to diagnose a heart attack, among others. The American regulator reports that biotin interference has caused falsely low troponin results.
The ratio makes it concrete. The daily requirement is around thirty micrograms, while hair supplements typically contain many times that.
If you take biotin, mention it at every blood test. That is not excessive caution but practical information for your doctor.
Zinc and selenium
Both appear in almost every hair supplement and for both the evidence for supplementation is weak. With selenium it is also risky.
For zinc the evidence is insufficient and inconsistent. The literature does not recommend screening for zinc in diffuse or hereditary hair loss, and double blind trials in alopecia areata are lacking.
With selenium the picture is clearer still. The evidence for supplementation is insufficient, while too much selenium is a known cause of hair loss.
That is an uncomfortable combination. A nutrient with little demonstrated benefit and a real risk on overdose sits in products promising hair growth.
Meanwhile both may legally claim to contribute to the maintenance of normal hair. One of the next sections covers that, because the claim means something other than people assume.
When supplements cause hair loss
This is the section I consider most important. More is not better here but demonstrably worse.
The upper limit for selenium in adults is four hundred micrograms a day. Chronically above that can cause selenosis, among whose signs are hair loss and brittle or discoloured nails.
That is not theoretical. In a documented outbreak involving a supplement containing two hundred times the labelled amount of selenium, most of those affected developed severe hair loss.
For preformed vitamin A the upper limit is three thousand micrograms of retinol activity equivalents a day. Excess is linked to hair loss, and retinoids also appear on the list of medicines that can trigger telogen effluvium.
The dermatology association sums it up briskly itself: getting too much of certain nutrients, including selenium, vitamin A and vitamin E, has been linked to hair loss. Anyone stacking several supplements runs that risk without knowing it.
What may legally be claimed
European rules are surprisingly useful here, because they constrain the marketing. They tell you exactly which claims have been assessed.
Under the European regulation listing permitted health claims, only biotin, selenium and zinc may claim to contribute to the maintenance of normal hair. Copper may separately claim to contribute to normal hair pigmentation.
Iron, vitamin D and vitamin E do not have that claim. Everything you read on a package about thicker, faster or fuller hair falls outside it.
Note the wording itself: maintenance of normal hair. That is different from improvement, and it concerns normal functioning rather than growth.
Combination products also failed at assessment. For mixtures of B vitamins with biotin and pumpkin seed oil, and for a keratin, copper and zinc combination, no cause and effect relationship with the maintenance of normal hair could be established.
Collagen, gummies and the rest
This category grows fastest and has the least to show. I keep it short because there is little to report.
The dermatology association describes the effectiveness of biotin, collagen and probiotics as often inconsistent or unreliable. Collagen has no authorised hair claim in the European Union.
Gummies deserve extra attention because they feel like sweets. They are not sweets: the biotin in them disturbs your blood test just as effectively.
What I see in practice is predictable. People take a supplement for months, see no difference, and switch brand rather than approach.
The money is better spent on a good haircut and less heat. That is not a joke but arithmetic over a year.
What your plate does do
Nutrition affects the hair still to grow, not the hair already there. That boundary runs exactly along your scalp.
The hairs you see in the mirror are dead tissue. No vitamin changes them retroactively.
What a varied diet with enough protein does is support the next few centimetres. Meat, fish, eggs, pulses, nuts, seeds, wholegrains and green vegetables cover the nutrients in this article comfortably.
Crash diets are the most damaging thing in this context. Rapid weight loss and unbalanced diets appear in the medical literature as recognised triggers for telogen effluvium.
That is a more useful lever than any supplement. Anyone eating normally rarely develops a deficiency that reaches their hair.
Other causes of hair loss
Vitamins are rarely the explanation, and that is good news because the real causes are more often addressable. Three come up most.
Telogen effluvium follows a trigger that usually sits about three months earlier, with a range of one to six months. Fever, surgery, childbirth, a crash diet or iron deficiency are known triggers, and it usually resolves on its own.
Hereditary hair loss is the second and progresses gradually in a recognisable pattern. The British NHS names finasteride and minoxidil as the main treatments in men. For women it names only minoxidil and states plainly that women should not use finasteride, and both work only for as long as they are used.
The third is the only one connected to styling and is called traction alopecia. Sustained pull from tight styles damages the follicles, and that damage eventually becomes permanent.
And then there is something that looks like shedding but is not: breakage. There is more on that in the article about making hair grow faster.
When to see a doctor
There are clear moments when a supplement is beside the point and a consultation is not. Four signals are enough to go on.
- Sudden or unusually heavy shedding, or shedding that lasts beyond a few months.
- Round bald patches, since that is a different condition from diffuse shedding.
- A painful, flaking, itching or inflamed scalp.
- Shedding alongside fatigue, weight change or other symptoms.
Your doctor decides which blood tests make sense, and that is the logical first step. That costs one round of effort and saves months of guessing.
Mention which supplements you take, biotin in particular. That is exactly where the story about disturbed laboratory tests becomes practical.
What I can do as a hairdresser is notice and care for, not diagnose. What I do recognise is the difference between hair that breaks and hair that sheds, and that sometimes saves a wrong search.
For advice on caring for thinning hair you can get in touch. There is more on daily routines under hair care.
Frequently asked questions about hair vitamins
Which vitamin is best for your hair?
There is not one. Only correcting a demonstrated deficiency has evidence behind it, and that means a blood test at your doctor rather than a tub from the chemist.
Does biotin really help against hair loss?
Only if you have a genuine biotin deficiency, and that is rare. A 2017 review found eighteen reported cases in which biotin helped, and in every one the patiënt had an underlying condition or a demonstrated deficiency.
Which deficiencies show up with hair loss?
Iron is the best supported, especially in women with diffuse shedding, and vitamin D in alopecia areata. For zinc, selenium, vitamin E, folic acid and B12 the literature finds the evidence too thin to screen for routinely; what makes sense in your case is for your doctor to decide.
Can supplements cause hair loss?
Yes, and it is rarely mentioned. Chronically high selenium intake can cause selenosis, with hair loss and brittle nails among its signs, and excess vitamin A is likewise linked to hair loss.
Which vitamins may legally make a hair claim?
In the European Union only biotin, selenium and zinc may claim to contribute to the maintenance of normal hair. Copper may separately claim to contribute to normal hair pigmentation, and nothing else is permitted.
Does collagen work for hair?
The dermatology association describes the evidence for biotin, collagen and probiotics as often inconsistent or unreliable. Collagen has no authorised hair claim in the European Union.
How much hair is normal to lose daily?
Fifty to a hundred hairs a day, and you usually do not notice. Roughly eighty five to ninety percent of your hairs are in the growing phase and the rest are cycling.
When should I see a doctor about hair loss?
With sudden or unusual shedding, bald patches, a painful or flaking scalp, or if it continues beyond a few months. Your doctor decides which blood tests make sense, and that is the logical first step.
The essentials
Only correcting a demonstrated deficiency has evidence, and iron is the best supported nutrient there. Get tested before you swallow, because inventing a deficiency helps nobody.
Biotin sits in almost every hair supplement and has the weakest support, while high doses do interfere with laboratory tests including the troponin test. So always mention it at a blood test.
Too much selenium or vitamin A is itself linked to hair loss, and in the European Union only biotin, selenium and zinc may claim anything about normal hair. Sudden shedding belongs with a doctor rather than a web shop.