Overview

• Published in Nutrition and Health, the PRISMA‑guided review pooled 17 studies with 61,332 participants, a sample heavily dominated by one large cohort and predominantly female (~97%).
• High intake of sugary beverages—more than 3,500 ml per week, roughly 11 cans—was repeatedly associated with increased hair loss, particularly in men, and alcohol use was tied to greater loss and premature greying.
• Lower vitamin D levels were consistently linked to more severe alopecia areata and androgenetic alopecia, while evidence in women suggested iron deficiency worsened outcomes and supplementation supported hair growth.
• Several small trials of supplements and extracts, including marine protein complexes, eggshell membrane, green tea and persimmon leaf, reported improvements in hair measures but many carried a high risk of bias and no meta‑analysis was possible.
• Researchers cited potential mechanisms involving excess sebum and inflammation from high sugar intake and recommended limiting sugary and alcoholic drinks and ensuring key nutrients, with the caveat that findings remain associative.