Sulphur-containing amino acids (cystine, cysteine) are essential components for the health of normal hair. Cystine is used in the treatment of many forms of hair loss. Vitamin B6 (pyridoxine) plays an important role in the development and maintenance of the skin and it is useful in reducing hair loss. Cystine is needed for proper Vitamin B6 utilization in the body. Vitamin B6 also speeds up how Cystine gets incorporated into the body.
D'Agostini and colleagues performed some very fascinating studies looking at the B6/cystine pair. In a 2007 study they showed that vitamin B6 and cystine prevented smoke induced hair loss in mice.
They demonstrated a study in 2013 that the combined oral administration at high dosages of L-cystine and vitamin B6 prevented hair loss from doxorubicin chemotherapy in mice.
Conclusion: There may be a role of cystine and B complex vitamins including vitamin B5 and B6 in human hair health. It seems that we may be entering a new era in understanding how to use supplements. Even when cystine dietary intake is good, there may be benefits in supplementation - especially in those with excessive shedding. Cystine use in sheep (to make more wool) has been studied since the early 1930s. These early studies showed that increasing cystine delivery to sheep helped these sheep produce more wool. It is important to check with your physician for how much of any supplement to take and for how long. 20 mg L-cystine and 100 mg B6 are often appropriate for short periods. Whether and how the supplement n-acetyl cystine (NAC) - a precursor of cystine- can be used in place of cystine remains to be determined.
D'Agostini F, et al. Chemoprevention of smoke-induced alopecia in mice by oral administration of L-cystine and vitamin B6. J Dermatol Sci. 2007.
D'Agostini F, et al.Chemoprevention of doxorubicin-induced alopecia in mice by dietary administration of L-cystine and vitamin B6. Arch Dermatol Res. 2013.
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Vancouver office at 604.283.9299