Diet and hair: protein, biotin and the supplements that matter

Key takeaways

• Hair follicles divide rapidly, so crash diets, low protein and iron deficiency can trigger shedding.
• Iron deficiency is the most common nutritional deficiency in the world and is linked to shedding. Ferritin is the usual test for iron stores.
• Biotin deficiency is rare in people eating a normal diet, and there is no good evidence that extra biotin grows hair. High doses can distort blood test results.
• Excess vitamin A and selenium, often from stacking several supplements, can cause hair loss.
• A diet with dal, paneer, curd, eggs, chana, soya and sprouts covers most needs for most people.

Why does diet affect hair at all?

See, what happens is, the cells at the base of each growing hair divide very quickly. A 2019 review on vitamins, minerals and hair loss explains that micronutrients are involved in this rapid cell turnover and in immune function around the follicle. When the body is short of energy, protein or key nutrients, it treats hair as non-essential. Your body is practical. Growing hairs can shift into the resting phase together, and two to three months later you see heavy shedding (telogen effluvium).

That is why the NHS lists weight loss and iron deficiency among the causes of temporary hair loss. It is also why people on rapid weight loss plans often notice hair fall; see hair loss on weight loss medicine.

Are you eating enough protein?

Hair is made mostly of a protein called keratin. When I ask people what they ate yesterday, the answer is often rice, roti and sabzi, with protein as a small side. Hostel food, skipped breakfasts, fasting days and "only salad" diets make it worse.

So I ask one simple question: does every main meal have a clear protein source? Practical options:

• Breakfast: besan chilla, moong dal chilla, paneer bhurji, eggs, sprouts poha, curd with fruit
• Lunch and dinner: a proper katori of dal or rajma or chole, paneer or tofu, soya chunks, fish, chicken or eggs
• Snacks: roasted chana, peanuts, a glass of buttermilk or milk, a handful of nuts

If you are vegetarian, combining pulses with grains through the day (dal-rice, rajma-chawal, khichdi) and including dairy or soya daily helps. If you have kidney disease or another medical condition, check your protein target with your doctor first.

Which nutrients matter most for hair?

What about iron?

The 2019 review notes that iron deficiency is the most common nutritional deficiency in the world and contributes to telogen effluvium. Serum ferritin is used as a marker of total body iron stores. But it can be falsely raised during infection or inflammation, so I never read it alone. The review discusses that some clinicians supplement when ferritin is below 40, though the link between ferritin and hair loss has been debated for years.

In India, heavy periods, a mainly vegetarian diet, pregnancy and the habit of tea with meals (which reduces iron absorption) make low iron stores common in women. Iron tablets can cause constipation and stomach upset, and too much iron is harmful. So take them only after a test, and recheck. See which blood tests matter for hair fall.

Does biotin help hair grow?

This is the most heavily marketed hair supplement, so let me be clear. The US National Institutes of Health Office of Dietary Supplements says biotin deficiency is rare and that severe deficiency has never been reported in healthy people eating a normal mixed diet. The evidence that biotin improves hair in people who are not deficient is weak: a few case reports and small studies, many without a placebo group.

There is also a practical risk. High-dose biotin, which is common in hair, skin and nail supplements, can interfere with some laboratory tests and cause falsely high or low results, including thyroid tests. The US FDA has advised doctors to consider biotin interference when results do not fit the clinical picture. If you take biotin, tell your doctor before any blood test.

And here is the pattern I see. Someone takes biotin, sees no change, adds a second supplement, then a third. That is how vitamin A and selenium overdoses happen.

Can supplements make hair loss worse?

Yes, they can. The 2019 review notes that too much vitamin A can contribute to hair loss, as can too much selenium. Many "hair vitamin" packs, multivitamins and beauty gummies contain both. Take two or three products together, add a fish liver oil, and your intake can go well above what you need.

My practical step: before you add anything, read the labels of everything you already take, and bring them all to your consultation. Honestly, a carry bag of bottles tells me more than people expect.

Will a better diet stop pattern hair loss?

No, and I would rather tell you that now. Pattern hair loss (androgenetic alopecia) is driven by genetics and how sensitive the follicle is to hormones. A good diet supports overall hair health and helps if a deficiency is adding to the problem, but it cannot reverse follicle miniaturisation. The 2019 review found that neither biotin nor vitamin E supplementation is supported for treating pattern hair loss or telogen effluvium. Treating pattern hair loss is a separate, medical decision.

How we approach this at Dr Tvacha

At a hair diagnosis I ask about your diet, fasting habits, periods, recent weight change and every supplement you take. I suggest blood tests only where they will change the plan, and I prescribe supplements only when a deficiency is found or likely. Quite often I stop products rather than add them. The hair plan page explains how the diagnosis works at our Thane, Andheri, Bandra and Dahisar centres.

Written by

Dr Amit KarkhanisAesthetic Physician · MBBS, Dip. Dermatology (UK) · Reg. No. 2001/02/1124

Founder of Dr Tvacha, practising in Thane since 2005. Leads the weight loss and hair programmes.