Randomized controlled trial of oral omega-3 PUFA in solar-simulated radiation-induced suppression of human cutaneous immune responses1-3

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Pilkington, Suzanne M. ; Massey, Karen A. ; Bennett, Susan P. ; Al-Aasswad, Naser M I ; Roshdy, Khaled ; Gibbs, Neil K. ; Friedmann, Peter S. ; Nicolaou, Anna ; Rhodes, Lesley E. (2013)
  • Publisher: American Society for Nutrition
  • Related identifiers: doi: 10.3945/ajcn.112.049494
  • Subject: Medicine (miscellaneous) | /dk/atira/pure/subjectarea/asjc/2900/2916 | Nutrition and Dietetics | /dk/atira/pure/subjectarea/asjc/2700/2701
    mesheuropmc: food and beverages

BACKGROUND: <br/><br/>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.<br/><br/>OBJECTIVES: <br/><br/>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).<br/><br/>DESIGN: <br/><br/>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.<br/><br/>RESULTS: <br/><br/>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.<br/><br/>CONCLUSION: <br/><br/>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.<br/>
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