The gut microbiome is known to help in metabolizing various essential vitamins, including those that support the growth of our hair such as biotin.1 Biotin helps metabolize amino acids, which produce keratin—the building block of our hair. When there’s an imbalance in gut bacteria, the process of synthetizing the biotin is disrupted, which in turn could have effects on the hair.
It is believed that gut bacteria may also help in regulating the hormone levels in our bodies, including those responsible for hair growth: testosterone, estrogen and cortisol. These hormones affect the growth cycle of the hair.
The microbiome contains a group of microbes called estrobolome, whose role it is to help metabolize estrogen. If the estrobolome is not healthy it may affect the estrogen levels, which in turn can lead to the development of estrogen-related conditions and the disruption of processes over which this hormone has an influence,2 such as hair growth.
The hair growth cycle (or to be specific the hair follicle’s transformation) goes through 3 distinct stages: growth (anagen), regression (catagen) and resting (telogen). A drop in the hormone can lead to the disruption of the anagen phase.