The relationship between diet and hair loss is one of the most frequently misunderstood areas in hair health. Nutritional deficiency can cause significant hair loss that is entirely reversible once the deficiency is corrected — but supplementation in the absence of a genuine deficiency is unlikely to make any difference to genetically driven hair loss.
Iron deficiency is the most common nutritional cause of hair loss in women and is also seen in men with restricted diets. Ferritin (stored iron) levels below 30 ng/mL are associated with increased hair shedding, even in patients who are not technically anaemic. A standard blood test will reveal your ferritin level.
Zinc deficiency affects the protein synthesis required for hair growth and is associated with diffuse hair thinning. It is seen in patients with inflammatory bowel conditions, strict vegan diets, or those who have recently undergone bariatric surgery.
Vitamin D deficiency is widespread in the UK due to limited sun exposure and is linked to alopecia areata as well as general hair thinning. Supplementation in deficient patients has been shown to improve hair loss outcomes in some studies.
Protein intake is another factor. Hair is primarily composed of keratin, a protein. Severe protein restriction — through crash dieting or eating disorders — impairs the body’s ability to produce adequate hair, causing a form of telogen effluvium.
If you are concerned that nutritional factors are contributing to your hair loss, a blood test panel covering full blood count, ferritin, zinc, vitamin D, and thyroid function is a sensible starting point. Treat identified deficiencies before spending money on supplements that may have no clinical basis in your specific case.
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