'Relaxers' damage hair: evidence from amino acid analysis.
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.


CONCLUSIONS
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.
Khumalo
Nonhlanhla P
NP
Division of Dermatology, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa.
Stone
Janet
J
Gumedze
Freedom
F
McGrath
Emily
E
Ngwanya
Mzudumile R
MR
de Berker
David
D
D000293:Adolescent; D000328:Adult; D000596:Amino Acids / Q000032:analysis*; D001120:Arginine / Q000032:analysis; D044383:Black People; D002956:Citrulline / Q000032:analysis; D003553:Cystine / Q000032:analysis; D005260:Female; D005973:Glutamine / Q000032:analysis; D006197:Hair / Q000737:chemistry / Q000187:drug effects*; D006203:Hair Preparations / Q000009:adverse effects* / Q000494:pharmacology; D006801:Humans; D054463:Trichothiodystrophy Syndromes / Q000139:chemically induced
D000596:Amino Acids; D006203:Hair Preparations; D005973:Glutamine; D002956:Citrulline; D003553:Cystine; D001120:Arginine