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

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. In the active EPA-rich PUFA group, 36 participants were analyzed for the contact hypersensitivity outcome and 35 for RBC EPA content.

Oral EPA-rich omega-3 PUFA capsules were given at 5 capsules per day with breakfast for 12 weeks. Each 1-g gelatin capsule contained about 70% EPA and 10% DHA. The comparator was identical-appearing oral capsules containing glyceryl tricaproate/caprate with medium-chain fatty acids.

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 verification is needed.

Small, highly selected sample of nickel-allergic women with phototypes I-II from one UK center limits generalizability. The primary photoimmunosuppression outcome was not significant across all SSR doses, and the intervention lasted only 12 weeks. The study was not powered to establish a robust dose-response effect for UVR suppression.