Dietary fish-oil supplementation in humans reduces UVB-erythemal sensitivity but increases epidermal lipid peroxidation.
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 fatty acids upon susceptibility to UVB-induced erythema and epidermal lipid peroxidation. Fifteen volunteers took 10 g fish oil, containing 18% eicosapentaenoic acid and 12% docosahexaenoic acid, daily for 3 or 6 months. Sensitivity to UVB was assessed at intervals on fish oil, and 2.5 months after stopping treatment. Paired skin shave biopsies were taken from six subjects, at baseline and 3 months, from both irradiated and control skin. Fatty acid composition was analyzed and thiobarbituric acid-reactive substances measured as an index of lipid peroxidation. With increasing time on fish oil the minimal erythema dose rose progressively, from 18.9 +/- 13.9 mJ/cm2 (mean +/- SD) at baseline to 41.1 +/- 16.6 mJ/cm2 at 6 months, p < 0.01. Ten weeks after stopping fish oil the minimal erythema dose fell to 23.1 +/- 4.9 mJ/cm2, 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. This was accompanied by a rise in thiobarbituric acid-reactive substances in irradiated skin from 6 +/- 0.3 (mean +/- SEM) to 18.5 +/- 2.6 A532/g skin, p < 0.01. Hence dietary omega-3 fatty acids produce a pronounced 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.
Dermatology Unit, Royal Liverpool University Hospital, U.K.
L E
LE
Rhodes
S
S
O'Farrell
M J
MJ
Jackson
P S
PS
Friedmann
D000293:Adolescent; D000328:Adult; D000368:Aged; D004042:Dietary Fats, Unsaturated; D004890:Erythema / Q000139:chemically induced; D015525:Fatty Acids, Omega-3 / Q000032:analysis; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage* / Q000494:pharmacology; D006801:Humans; D008054:Lipid Peroxides / Q000378:metabolism*; D008875:Middle Aged; D012867:Skin / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects; D014466:Ultraviolet Rays
D004042:Dietary Fats, Unsaturated; D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D008054:Lipid Peroxides