Veggie Blog

Many people notice thinning hair and look for a vitamin that will fix it. The old version of this post said that baldness is caused by not having enough vitamin B, that biotin shampoo “gets into the root tips,” and that men who eat foods rich in vitamin B are less likely to lose hair. None of that is supported. Hair loss has several causes, and a supplement helps only in one of them, a true deficiency. Here is what the evidence shows.

What causes hair loss?

The most common cause is heredity. MedlinePlus explains that both men and women tend to lose hair thickness as they age, and that pattern baldness is related to aging, heredity and changes in the hormone testosterone, and is not usually caused by a disease. The American Academy of Dermatology (AAD) describes other causes, including childbirth, illness or a stressful time, which can cause a lot of shedding a few months later. In most cases the shedding stops and hair regains its normal fullness within 6 to 9 months. Thyroid disease and crash diets without enough protein can also cause hair loss. So the idea that baldness is simply a vitamin B problem is wrong.

Can too little of a nutrient cause hair loss?

Yes, in some cases. AAD says that if you do not get enough biotin, iron, protein or zinc, you can have noticeable hair loss, and that when your body gets enough of the missing nutrient, hair can regrow. MedlinePlus notes that if you have a certain vitamin deficiency, your provider will likely recommend a supplement. The key word is deficiency. A blood test is the way to find out. Our post on vitamin deficiency: who is at risk and why to test before you supplement explains how this works.

Does biotin help hair grow?

The NIH Office of Dietary Supplements reports that biotin deficiency can cause thinning hair, and so biotin supplements are often promoted for hair, skin and nail health. But the evidence is thin: only case reports support the claim, and these were in children, including a rare disorder called uncombable hair syndrome. ODS concludes that future studies are needed to determine whether biotin supplements might improve hair health, especially in healthy people. Biotin is found in many foods, and true deficiency is uncommon. The old post said that biotin in shampoo reaches the root tips faster, and I could not find any support for that claim.

Why can biotin supplements be a problem?

Very high biotin intakes can interfere with common laboratory tests. ODS says that biotin may produce falsely normal or abnormal results in tests that measure thyroid hormones and other substances. A single 10 mg dose has interfered with thyroid tests taken within 24 hours. Most seriously, according to the FDA, a patient with a high intake of supplemental biotin died after a troponin test, used to help diagnose a heart attack, gave a falsely low result. The FDA advises health care providers to ask patients about biotin. So if you take biotin, tell your doctor and any lab before blood tests. You can read the details in the ODS biotin fact sheet.

What about vitamins A and E?

The old post said that vitamins A and E are needed for hair growth. They are needed for general health, but more is not better. The AAD notes that taking large amounts of vitamin A or selenium is toxic and can cause hair loss. ODS warns that too much preformed vitamin A from supplements can cause severe headache, blurred vision and other problems. Our guide to vitamin E and your body explains why you do not need high doses of it.

What should you do about thinning hair?

See your doctor or a dermatologist if hair loss is sudden, patchy or comes with other symptoms such as tiredness or weight change. They can check for thyroid problems, low iron and other causes, and discuss treatments such as minoxidil. A balanced diet with enough protein, iron and zinc supports healthy hair, but it will not stop inherited hair loss. Do not take high-dose supplements on your own. For general guidance on picking and taking supplements safely, see vitamins and your health.