In short: the deficiency most clearly linked to hair fall is iron (a mineral). Vitamin D, B12 and zinc deficiencies are associated with hair loss and are common in India, but whether they cause it is less certain. Biotin deficiency is rare. Test before you supplement, because several of these are harmful in excess.
The evidence, deficiency by deficiency
| Nutrient | Link to hair loss | Common in India? | Test | Too much is harmful? |
|---|---|---|---|---|
| Iron (ferritin) | Strongest. Linked to shedding and worse pattern thinning | Very common in women | Serum ferritin, CBC | Yes |
| Vitamin D | Associated with shedding and alopecia areata; cause vs effect unclear | Very common | 25-OH vitamin D | Yes (high doses) |
| Vitamin B12 | Possible link; causes anaemia and tiredness | Common in vegetarians | Serum B12 | Low risk |
| Zinc | Real but uncommon deficiency; can cause hair loss | Sometimes | Serum zinc | Yes (can cause copper deficiency) |
| Folate | Limited evidence | Sometimes | Serum folate | Low risk |
| Biotin | Deficiency rare; supplements don't help if levels are normal | Rare | Rarely tested | Distorts lab tests |
| Protein / calories | Severe shortfall or crash diets → shedding | With crash diets | Diet history | n/a |
Too much can also cause hair loss: excess vitamin A and selenium are known causes.
Vitamin D and hair
- Low vitamin D is very common in India, even in sunny cities, because of indoor lifestyles, covered skin and darker skin needing more sun.
- Studies find lower vitamin D in people with hair loss, but supplementing doesn't reliably regrow hair unless you're deficient.
- Correct it if low, under a doctor: high doses taken without monitoring can cause harmful calcium levels.
- Recovery: if deficiency contributed, shedding may ease over several months after levels improve.
Vitamin B12 and hair
- Mainly found in animal foods, so vegetarians and vegans are at higher risk. Long-term use of metformin or acid-reducing medicines can also lower it.
- Deficiency causes anaemia, tiredness, tingling and memory problems. Treat it for your overall health; hair may improve as a side benefit.
Which tests to ask for
For unexplained hair fall, doctors commonly check: CBC, ferritin, TSH, vitamin D, B12, and sometimes zinc. Women with signs of PCOS may need hormone tests too. → Cause finder
Before tests: stop biotin supplements a few days beforehand (ask your doctor).
Should I just take a multivitamin or hair gummies?
- If you're not deficient, hair vitamins are unlikely to help, and they're not a substitute for finding the cause. → Biotin · Hair growth tablets
- If you are deficient, a targeted supplement at the right dose works better than a general hair gummy.
See a doctor soon if you have: round bald patches that appear suddenly · hair coming out in clumps · redness, pain, pus, scaling or scarring on the scalp · hair loss with fever, weight loss, irregular periods, acne or new facial hair · eyebrow or eyelash loss · hair loss in a child.
Sources
- Almohanna HM, et al. The role of vitamins and minerals in hair loss: a review. Dermatol Ther (Heidelb). 2019;9:51–70.
Medical review pending: not yet reviewed by a dermatologist. Medical disclaimer
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