Vitamin D, iron, and protein may improve hair growth and thickness while sugar-sweetened beverages and alcohol may worsen hair loss. Digest
Hair loss affects self-image and mental well-being, yet evidence on whether diet can prevent or improve it has been inconsistent. To clarify the picture, researchers systematically reviewed human studies examining how individual foods, nutrients, and supplements influence hair health.
They analyzed 17 studies involving over 61,000 participants, mostly women, spanning childhood to older age. Only studies on specific foods or nutrients were included, not whole-diet patterns. The studies examined a range of hair-related conditions, including alopecia areata (a patchy, autoimmune form of hair loss), androgenetic alopecia (commonly known as male or female pattern hair loss), and general hair thinning or shedding.
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Several consistent patterns emerged across the evidence:
- Low vitamin D levels correlated with greater severity and longer duration of alopecia areata and with worse premature androgenetic alopecia in men.
- Iron supplementation improved self-reported hair growth in women with low iron status and alopecia.
- Protein deprivation reduced the diameter and pigmentation of hair bulbs, indicating compromised hair quality.
- Higher intake of cruciferous vegetables was linked to less hair loss, with soy intake showing a similar but weaker trend.
- Drinking more than 3.5 liters of sugar-sweetened beverages per week was associated with male pattern hair loss, and alcohol use related to greater hair loss and earlier greying.
- A marine protein supplement reduced hair shedding and promoted growth in women with temporary thinning. Hydrolyzed eggshell membrane increased hair density.
These findings fit plausible mechanisms. Vitamin D helps regulate follicle regeneration through Wnt/β-catenin signaling. Iron supports DNA synthesis in fast-dividing follicle cells. Adequate protein is needed for keratin, the main hair protein. Sugary diets may increase scalp oil and inflammation, while cruciferous vegetables and soy supply antioxidant and anti-inflammatory compounds that can reduce follicle stress.
While the results of the study point to clear dietary signals, most included studies were observational or high-risk clinical trials, and outcome measures varied widely. Explore other evidence-based approaches to reversing hair loss and graying in Aliquot #112.