Dietary Isoflavone Increases Insulin-Like Growth Factor-I Production, Thereby Promoting Hair Growth in Mice

In the study from 2011, researchers found that dietary isoflavone increased insulin-like growth factor-I (IGF-I) production, which in turn promoted hair growth in wild-type (WT) mice. Isoflavone significantly raised CGRP mRNA levels in dorsal root ganglion neurons and IGF-I production in the skin of WT mice, leading to enhanced hair follicle morphogenesis, hair regrowth, and pigmentation. These effects were not observed in CGRP-knockout (CGRP-/-) mice, indicating the importance of CGRP in the process. The study concluded that isoflavones could promote hair growth by increasing IGF-I production in hair follicle dermal papilla cells via the increase of CGRP production in sensory neurons. The number of mice used in each experimental group was five.