Dietary Vitamin A Dose Dependently Regulates BMP4 and WNT7A in Hair Follicles

The study, conducted by Helen B. Everts and her team in 2017, investigated the effects of dietary vitamin A on hair follicle regulation, specifically focusing on bone morphogenetic protein 4 (BMP4) and wingless-related MMTV integration site 7A (WNT7A) expression. The research involved female C57BL/6J mice aged 70-100 days and was designed to further define hair cycle changes. The results showed that dietary vitamin A altered the hair cycle in a dose-dependent manner. In mice bred on a high retinoic acid (RA) diet, excess vitamin A (56 IU) increased BMP4 and reduced WNT7A, suggesting that excess vitamin A arrests hair follicles in refractory telogen, similar to the effects of oral retinoids in humans. However, in mice bred on an adequate RA diet, the reverse was observed; excess vitamin A (56 IU) reduced BMP4 and increased WNT7A, indicating that physiological levels of dietary vitamin A promote competent telogen, which allows hair follicle stem cells to be activated. The study concluded that further research is needed to better define these dose-dependent effects.