Dietary Vitamin A Regulates Wingless-Related MMTV Integration Site Signaling to Alter the Hair Cycle

The study found that dietary vitamin A activates hair follicle stem cells in mice in a dose-dependent manner, which induces the growth phase of the hair cycle and could make follicles more susceptible to autoimmune attack in alopecia areata. High levels of vitamin A were shown to increase WNT signaling within the hair follicle, with significant effects observed at doses as low as 4 IU vitamin A/g diet. The research suggests that retinoic acid regulates WNT signaling in developing hair follicles, and the authors aim to further explore this mechanism and establish a healthy range of retinoids for hair follicles, potentially aiding in the treatment of hair loss diseases. The study used doses of vitamin A 3-7 times higher than recommended for humans, which could be toxic, but are commonly consumed by mice and some Americans through supplements.