Correlation between tryptophan and hair pigmentation in human hair

Abstract

The concentration of tryptophan in human hair of various colours is determined in order to study their correlation with hair pigmentation. The mean levels of this amino acid in hair samples are higher in men than in women. Therefore, sex influences the content of tryptophan in human hair. In addition, age influences the distribution, the highest levels are observed in the 1-5 year age-group and in ageing subjects in the groups up to 61-80 years in both sexes. The hair samples subdivided, according the colour, into blond, dark blond, red, light brown, brown, black, grey, and white demonstrate that in both sexes the concentrations of tryptophan are higher in brown and black hair than in blond hair. However, the tryptophan levels are highest in grey and white hair, showing that tryptophan accumulates among hair fibres with age. Therefore, there is a correlation between tryptophan content and hair pigmentation.