Overview

• The review, published in Nutrition and Health, synthesized 17 studies spanning 61,332 participants and was conducted under PRISMA guidelines with PROSPERO registration.
• High intake of sugary beverages—more than 3,500 ml per week—was correlated with greater hair loss, with several studies indicating a stronger association in men.
• Alcohol consumption was associated with increased hair loss and premature hair depigmentation in observational research.
• Lower serum vitamin D levels were linked to more severe alopecia in multiple studies, while one large cohort found no association, and iron supplementation in women was tied to improved hair growth.
• Small trials of supplements and plant extracts reported benefits for hair parameters, but heterogeneity and high risk of bias prevented meta-analysis and prompted calls for rigorous controlled studies.