Le. Rhodes et al., DIETARY FISH-OIL SUPPLEMENTATION IN HUMANS REDUCES UVB-ERYTHEMAL SENSITIVITY BUT INCREASES EPIDERMAL LIPID-PEROXIDATION, Journal of investigative dermatology, 103(2), 1994, pp. 151-154
Ultraviolet radiation (UVR) - induced erythema may be mediated in part
by free radical-generated tissue damage, including lipid peroxidation
. We have examined the effect of dietary fish oil rich in omega-3 fatt
y acids upon susceptibility to UVB-induced erythema and epidermal lipi
d peroxidation. Fifteen volunteers took 10 g fish oil, containing 18%
eicosapentaenoic acid and 12% docosahexaenoic acid, daily for 3 or 6 m
onths. Sensitivity to UVB was assessed at intervals on fish oil, and 2
.5 months after stopping treatment. Paired skin shave biopsies were ta
ken from six subjects, at baseline and 3 months, from both irradiated
and control skin. Fatty acid composition was analyzed and thiobarbitur
ic acid-reactive substances measured as an index of lipid peroxidation
. With increasing time on fish oil the minimal erythema dose rose prog
ressively, from 18.9 +/- 13.9 mJ/cm(2) (mean +/- SD) at baseline to 41
.1 +/- 16.6 mJ/cm(2) at 6 months, p < 0.01. Ten weeks after stopping f
ish oil the minimal erythema dose fell to 23.1 +/- 4.9 mJ/cm(2), p < 0
.05. Epidermal total omega-3 fatty acids rose from 1.8 +/- 0.4% total
fatty acids (mean +/- SEM) to 24.2 +/- 3.9% at 3 months, p < 0.01. Thi
s was accompanied by a rise in thiobarbituric acid-reactive substances
in irradiated skin from 6 +/- 0.3 (mean +/- SEM) to 18.5 +/- 2.6 A(53
2)/g skin, p < 0.01. Hence dietary omega-3 fatty acids produce a prono
unced reduction in UVB-erythemal sensitivity, although susceptibility
of skin to lipid peroxidation is increased. Thus, omega-3 fatty acids
may act as an oxidizable buffer, protecting more vital structures from
free radical damage.