Greater carotenoid intake (118 meta-analyses) and blood carotenoid levels (32 meta-analyses) reduced the overall cancer risk by 18% to 19%. Similarly, the risk of specific cancers (gastrointestinal, prostate, breast, head and neck, bladder, gynecologic, skin, and blood) was reduced by 9% to 55% (1 to 48 meta-analyses).

Supplementation with beta-carotene increased the risk of lung (+14%, 4 meta-analyses) and bladder (+44%, 1 meta-analysis) cancers.

The included meta-analyses covered randomized controlled trials, cohort studies and case-control studies. The quality of 138 meta-analyses was low, 19 were moderate in quality, and 41 were high in quality.

Greater carotenoid intake and status are associated with reduced cancer risk Original paper