Randomized controlled trial of oral omega-3 PUFA in solar-simulated radiation-induced suppression of human cutaneous immune responses.
BACKGROUND
Skin cancer is a major public health concern, and the majority of cases are caused by solar ultraviolet radiation (UVR) exposure, which suppresses skin immunity. Omega-3 (n-3) PUFAs protect against photoimmunosuppression and skin cancer in mice, but the impact in humans is unknown.


OBJECTIVE
We hypothesized that EPA-rich n-3 PUFA would abrogate photoimmunosuppression in humans. Therefore, a nutritional study was performed to assess the effect on UVR suppression of cutaneous cell-mediated immunity (CMI) reflected by nickel contact hypersensitivity (CHS).


METHODS
In a double-blind, randomized controlled study, 79 volunteers (nickel-allergic women, 22-60 y old, with phototype I or II) took 5 g n-3 PUFA-containing lipid (70% EPA plus 10% DHA) or a control lipid daily for 3 mo. After supplementation, nickel was applied to 3 skin sites preexposed on 3 consecutive days to 1.9, 3.8, or 7.6 J/cm(2) of solar-simulated radiation (SSR) and to 3 unexposed control sites. Nickel CHS responses were quantified after 72 h and the percentage of immunosuppression by SSR was calculated. Erythrocyte [red blood cell (RBC)] EPA was measured by using gas chromatography.


RESULTS
SSR dose-related suppression of the nickel CHS response was observed in both groups. Photoimmunosuppression appeared less in the n-3 PUFA group than in the control group (not statistically significant [mean difference (95% CI): 6.9% (-2.1%, 15.9%)]). The difference was greatest at 3.8 J/cm(2) SSR [mean difference: 11% (95% CI: 0.5%, 21.4%)]. Postsupplementation RBC EPA was 4-fold higher in the n-3 PUFA group than in the control group (mean difference: 2.69% (95% CI: 2.23%, 3.14%), which confirmed the EPA bioavailability.


CONCLUSIONS
Oral n-3 PUFAs appear to abrogate photoimmunosuppression in human skin, providing additional support for their chemopreventive role; verification of study findings is required. This trial was registered at clinicaltrials.gov as NCT01032343.
Institute of Inflammation and Repair, University of Manchester, Manchester, UK.
Suzanne M
SM
Pilkington
Karen A
KA
Massey
Susan P
SP
Bennett
Naser Mi
NM
Al-Aasswad
Khaled
K
Roshdy
Neil K
NK
Gibbs
Peter S
PS
Friedmann
Anna
A
Nicolaou
Lesley E
LE
Rhodes
D000328:Adult; D003877:Dermatitis, Contact / Q000276:immunology / Q000517:prevention & control; D019587:Dietary Supplements; D004311:Double-Blind Method; D004912:Erythrocytes / Q000187:drug effects / Q000276:immunology; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage* / Q000097:blood; D005260:Female; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology / Q000528:radiation effects; D007111:Immunity, Cellular / Q000187:drug effects*; D008875:Middle Aged; D009532:Nickel / Q000009:adverse effects / Q000378:metabolism; D012867:Skin / Q000187:drug effects / Q000276:immunology* / Q000528:radiation effects; D012993:Solar Energy; D014466:Ultraviolet Rays / Q000009:adverse effects*; D055815:Young Adult
D015525:Fatty Acids, Omega-3; D009532:Nickel