One of the major hair concerns for both men and women is that of hair loss. For men the most obvious manifestation of this is male pattern baldness known as alopecia areata. However hair shedding resulting in hair thinning is also a concern for both men and women. Individuals suffering hair loss often experience psychological disadvantages, for example social phobia, anxiety, and depression, due to their change in appearance. This invention relates to a hair care composition comprising glabranin or a derivative thereof. The invention also relates to a cosmetic method for increasing hair fibre diameter, stimulating hair growth, retaining hair or reducing hair loss, stimulating hair follicle growth in anagen or telogen phases, increasing hair fibre density and preventing or treating alopecia.