The G (major) allele is associated with:
- GG= reduced BCMO1 activity by 48% (R).
- Participants with a G allele had a higher average beta carotene level than participants with a T allele (R).
The G allele may affect health negatively by reducing the availability of vitamin A (retinol) but also positively by increasing the plasma concentration of powerful antioxidant molecules. A number of studies have shown that higher plasma concentrations of antioxidant carotenoids are associated in a protective manner against the development of chronic diseases and disability (R).