Chinese Association of Idaho State University (CAISU)
Most hair loss is not associated with systemic or internal disease, nor is poor diet a frequent factor. Hair may simply thin as a result of predetermined genetic factors and the overall aging process. Many men and women may notice mild physiologic thinning of hair starting in their 30s and 40s. Life vicissitudes, including illness, emotional trauma, protein deprivation (during strict dieting), and hormonal changes like those in pregnancy, puberty, and menopause may cause hair loss.