‘Relaxers’ damage hair: Evidence from amino acid analysis
Accepted 14 April 2009.
Refers to article:
Commentary: Healthy hair and protein loss
Zoe Diana Draelos
Journal of the American Academy of Dermatology
March 2010 (Vol. 62, Issue 3, Pages 409-410) Full Text |
Full-Text PDF (52 KB)
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.
aDivision of Dermatology, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
bDepartment of Statistical Sciences, University of Cape Town, Cape Town, South Africa
cDepartment of Clinical Biochemistry, Bristol Royal Infirmary, Bristol, United Kingdom
dDepartment of Dermatology, Bristol Royal Infirmary, Bristol, United Kingdom
Reprint requests: Nonhlanhla P. Khumalo, Division of Dermatology, Groote Schuur Hospital, Ward G23, Observatory 7925, University of Cape Town, Cape Town, South Africa.
Funding sources: Dr Khumalo's post at the time of the study was funded by the Discovery Foundation of South Africa.
ABSTRACT