Biology of Hair Growth and Influence of External Factors (Ecology, Stress, Nutrition

In the article the biological mechanisms of hair growth are examined and the influence of external factors ecology, chronic stress, nutrition and nutraceuticals on their growth is assessed. The study is based on a systematic literature review with emphasis on original works concerning the molecular mechanisms of hair growth. A descriptive meta-analysis of the results of other publications as well as clinical trials was conducted and a data integration scheme for multidisciplinary prognosis of alopecia risks, incorporating biochemical and physiological parameters, was developed. Data were systematized on how air pollution, ultraviolet radiation and heavy metals disrupt the functions of the dermal papilla and the phase balance of the hair cycle. The molecular pathways of stress-induced hair loss via HPA axis hyperactivity, neuropeptide signaling and local inflammation are described. A conclusion is drawn on the necessity of a comprehensive multifactorial approach and monitoring of nutritional status for personalized therapy of hair loss. The information presented in this work will be of interest to specialists in trichology and dermatophysiology investigating molecular and cellular mechanisms of hair growth in the context of endocrine and immunological interactions. The material will also be valued by experts in ecotoxicology and nutrition seeking to integrate data on the impact of polluted environments, chronic stress and macro- and micronutrients into the development of preventive and therapeutic strategies to maintain physiological homeostasis of the hair follicle.