Effect of beta-carotene supplementation on photosuppression of delayed-type hypersensitivity in normal young men

The aim of this study was to examine whether beta-carotene protects against the immunosuppression seen with long-wave ultraviolet-light (UV-A) exposure. Free-living, healthy men, aged 19-39 y received 30 mg beta-carotene/d or a placebo while on a single-menu, low-carotenoid diet. After 28 d all subjects received 12 exposures to a UV-A/B light source over a 16-d period. The total UV-A dose received ranged from 15.9 to 19.3 J/cm2. The total shorter-wave ultraviolet-light (UV-B) dose varied from 1.59 to 1.96 J/cm2. Follow-up continued for 21 d. Carotenoid assays and delayed-type hypersensitivity (DTH) tests were performed at baseline, pre-UV, post-UV, and after follow-up. The DTH-test responses were significantly suppressed in the placebo group after UV treatments. The suppression was inversely related to plasma beta-carotene concentrations in this group. There was no significant suppression of DTH test responses in the beta-carotene group. It is concluded that beta-carotene protects against photosuppression of immune function.