Randomized controlled trial of oral omega-3 PUFA in solar-simulated radiation-induced suppression of human cutaneous immune responses.
What this study found
Oral EPA-rich omega-3 PUFA showed a limited protective effect against solar-simulated radiation-induced photoimmunosuppression. Across the 3 SSR doses, the between-group difference in nickel contact hypersensitivity suppression was 6.9% (P = 0.13), but at 3.8 J/cm2 the PUFA group had 11% less suppression than control (95% CI: 0.5%, 21.4%; P = 0.04). RBC EPA increased more in the PUFA arm than in control (3.62% vs 0.92%; mean difference 2.69%, 95% CI: 2.23%, 3.14%; P < 0.001). The authors concluded that EPA-rich omega-3 PUFAs may abrogate photoimmunosuppression in human skin, although…
- Study & population
- Randomized controlled trial in nickel-allergic adult women with sun-sensitive skin types I or II enrolled at a single center in Manchester, United Kingdom.
- Intervention
- Oral EPA-rich omega-3 PUFA capsules were given at 5 capsules per day with breakfast for 12 weeks.
- Key limitation
- Small, highly selected sample of nickel-allergic women with phototypes I-II from one UK center limits generalizability.
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Open PDFOriginal abstract
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. OBJECTIVES 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). DESIGN 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. CONCLUSION 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.