Nutrition and hair health go together, because hair follicles are among the most active cells in the body. They need a steady supply of energy, protein, vitamins and minerals to keep building hair. When supply falls short, hair is one of the first things the body economizes on.
How diet affects hair
- Too little energy or protein, as in crash diets, can trigger shedding two to three months later.
- A shortage of certain nutrients, especially iron, can cause diffuse thinning.
- Too much of some nutrients can also cause hair loss.
A varied, balanced diet covers the needs of most people. No single food makes hair grow faster.
Key nutrients and where to find them
| Nutrient | Why hair needs it | Food sources |
|---|---|---|
| Protein | Hair is made of the protein keratin | Meat, fish, eggs, dairy, beans, lentils, tofu, nuts |
| Iron | Carries oxygen to follicles; low stores are linked to shedding | Red meat, beans, lentils, dark green leafy vegetables, fortified cereals |
| Zinc | Supports cell growth and repair | Meat, shellfish, dairy, seeds, wholegrains |
| Vitamin D | Involved in the hair cycle | Sunlight on skin, oily fish, eggs, fortified foods |
| Vitamin B12 and folate | Needed to make new cells | Animal foods, fortified foods; folate in green vegetables and pulses |
| Vitamin C | Helps the body to absorb iron | Citrus fruit, berries, peppers, broccoli |
| Omega-3 fats | Part of a healthy scalp and skin | Oily fish, walnuts, flaxseed |
| Biotin | Helps to process nutrients | Eggs, nuts, seeds, wholegrains |
Iron deserves a special mention
Iron deficiency is one of the most common nutritional causes of hair shedding, particularly in people who have heavy periods, are pregnant, or eat little or no meat. Tiredness, shortness of breath and pale skin are other signs. Do not treat yourself with iron on a guess. A blood test confirms the diagnosis, and too much iron is harmful.
The truth about biotin
Biotin is the best-known "hair vitamin". True biotin deficiency is rare, and there is little evidence that extra biotin helps people who are not deficient. High-dose biotin supplements can also interfere with some blood tests, including tests of thyroid function and tests used when a heart attack is suspected. Tell your doctor if you take biotin before any blood test.
When supplements help and when they harm
Supplements are useful when a deficiency has been confirmed. Otherwise:
- Extra vitamins do not make healthy hair grow faster or thicker.
- Too much vitamin A and too much selenium can cause hair loss.
- Very high doses of some other nutrients carry their own risks.
- "Hair, skin and nails" products are not tested like medicines before they are sold.
Speak to a doctor or pharmacist before starting a supplement, especially if you are pregnant, breastfeeding or taking medicines.
Eating patterns that put hair at risk
- Very low-calorie or crash diets.
- Rapid weight loss, including after weight-loss surgery or with weight-loss medicines.
- Cutting out whole food groups without planning for replacements.
- Low-protein diets.
- Eating disorders.
If you follow a vegetarian or vegan diet, plan for iron, zinc, vitamin B12 and protein from plant sources or fortified foods.
A simple hair-friendly plate
- A portion of protein at each meal.
- Plenty of vegetables and fruit of different colors.
- Wholegrains for steady energy.
- Some healthy fats, such as nuts, seeds, olive oil or oily fish.
- Enough fluid through the day.
How long diet changes take to show
Hair grows about one centimeter a month, and the hair cycle is slow. After correcting a shortfall, expect three to six months before you notice less shedding or new growth. Hair Growth Cycle: How Hair Grows and Sheds explains the cycle.
When to see a doctor
See a doctor if you have ongoing shedding, a restricted diet, heavy periods, symptoms such as fatigue, or if you are considering supplements for hair loss. Hair Thinning: Causes and When to Get Help covers the other causes of thinning, and Stress and Hair Loss: Understanding Telogen Effluvium explains shedding after stress or rapid weight loss. Nails rely on good nutrition too. See Nail Growth: What Affects It and How to Track It. New mothers will find advice in Postpartum Hair Loss: What to Expect After Pregnancy.
Related on ArniSun
- Hair Thinning: Causes and When to Get Help
- Stress and Hair Loss: Understanding Telogen Effluvium
- Hair Growth Cycle: How Hair Grows and Sheds
- Nail Growth: What Affects It and How to Track It
- Postpartum Hair Loss: What to Expect After Pregnancy
Sources and further reading
Frequently asked questions
Which vitamin deficiency causes hair loss?
Low iron is the most common nutritional cause. Low vitamin D, zinc and vitamin B12 have also been linked to hair loss. A blood test is needed to find out.
Do hair growth supplements work?
They help only if they correct a deficiency you actually have. For people with adequate nutrition, evidence of benefit is weak.
Can eating more protein make my hair thicker?
If your protein intake was too low, restoring it helps hair to recover. Eating more than you need does not make hair thicker.