‘Relaxers’ damage hair: Evidence from amino acid analysis Nonhlanhla P. Khumalo, FCDerm, PhD, a Janet Stone, BSc, PhD, c Freedom Gumedze, PhD, b Emily McGrath, MRCP, d Mzudumile R. Ngwanya, FCDerm, a and David de Berker, MRCP d Cape Town, South Africa, and Bristol, United Kingdom See commentary on page 409 Background: ‘Relaxers’ are used by more than two thirds of African females to straighten hair, with easy grooming and increased length often cited as reasons. A recent study reported relaxed hair lengths much shorter than expected, suggesting increased fragility; the potential for scalp inflammation and scarring alopecia remains unclear. Objective: To investigate the biochemical effects of ‘relaxers’ on hair. Methods: With informed consent, included participants represented 3 groups: natural hair, asymptomatic relaxed hair, and symptomatic (brittle) relaxed hair. Biochemical analysis was performed by using a Biochrom 30 amino acid analyzer. Differences in amino acid levels were assessed using either Wilcoxon rank sum test or matched-pairs signed-rank test. Results: There was a decrease in cystine, citrulline, and arginine; however, an increase in glutamine was found in all relaxed compared to natural hair. Cystine levels (milligram per gram amino acid nitrogen) were similar in natural proximal and distal hair: 14 mg/g (range, 4-15 mg/g) versus 14 mg/g (range, 12-15 mg/g); P = .139. In asymptomatic relaxed hair, cystine levels were higher in less frequently relaxed samples proximal to scalp: 7.5 mg/g (5.6-12) versus 3.3 mg/g (1.3-9.2); P = .005. Cystine levels in distal asymptomatic relaxed and symptomatic relaxed hair were similar to each other and to those in the genetic hair fragility disease trichothiodystrophy. Limitations: It was not possible to analyze lye and no-lye ‘relaxers’ separately. Conclusions: ‘Relaxers’ are associated with reduced cystine consistent with fragile damaged hair. A decrease in citrulline and glutamine has been associated with inflammation; prospective studies are needed to investigate whether or how ‘relaxers’ induce inflammation. ( J Am Acad Dermatol 2010;62:402-8.) Key words: African hair; amino acids; cystine; hair fragility; hair relaxers; hair straightening. INTRODUCTION I ndigenous African hair varies from very curly in the southern part of the continent to nearly straight in northern areas. ‘African’ hair for the purpose of this article refers to the former—typically black, tight curly hair. Notwithstanding reported differ- ences in the distribution of high and low sulfur proteins, the amino acid analysis of different hair phenotypes 1-4 has proved to be similar. The latter proved to be similar despite significant differences in both appearance and behavior (eg, comb-ability and elasticity). 5,6 Curly hair in those persons of African origin is known to be vulnerable to breakage, whether subjects are African Americans 7 or indigenous Africans. 8 The latter may explain the observed short lengths of combed natural African hair even after many years without a haircut. 8,9 The breakage that From the Division of Dermatology, Groote Schuur Hospital, a and the Department of Statistical Sciences, University of Cape Town, b Cape Town; and the Departments of Clinical Bioche- mistry c and Dermatology, d Bristol Royal Infirmary. Funding sources: Dr Khumalo’s post at the time of the study was funded by the Discovery Foundation of South Africa. Conflicts of interest: None declared. Accepted for publication April 14, 2009. Reprint requests: Nonhlanhla P. Khumalo, Division of Dermatology, Groote Schuur Hospital, Ward G23, Observatory 7925, University of Cape Town, Cape Town, South Africa. E-mail: Nonhlanhla.khumalo@ uct.uct.ac.za. 0190-9622/$36.00 ª 2009 by the American Academy of Dermatology, Inc. doi:10.1016/j.jaad.2009.04.061 Abbreviations used: TN: trichorrhexis nodosa TTD: trichothiodystrophy 402