About Alpha-Carotene
A provitamin-A carotenoid with roughly half the vitamin A activity of beta-carotene. The human evidence is epidemiological: higher SERUM alpha-carotene tracks with lower lung-cancer death and all-cause mortality (e.g. NHANES III, HR ~0.24 for lung-cancer death in the top vs bottom levels). This is a marker of a carotenoid-rich diet, not proof that supplementing alpha-carotene helps — beta-carotene supplement trials (ATBC) actually raised lung-cancer risk in smokers. No RCTs of isolated alpha-carotene supplementation. Grade low.
What Alpha-Carotene supports
- Higher blood levels are associated with lower mortality in population studies (association only)
- Converts to vitamin A (about half the activity of beta-carotene)
How much Alpha-Carotene to take
The RDA prevents deficiency. The effective range is what clinical trials used to actually move the outcome.
Effective
0–0
mcg
No established therapeutic dose. Alpha-carotene is a minor provitamin-A carotenoid usually present as a natural companion to beta-carotene in mixed-carotenoid or algae blends, at trace amounts. Nominal placeholder range.
Clinical evidence
Limited clinical evidence. Provitamin-A carotenoid; epidemiological serum associations only, no supplementation RCTs.
NIH Fact Sheet