Plasma concentrations of carotenoids and VA metabolites are shown in Table 4. Synthetic βC 1X did not differ from RP for any of themeasured plasma carotenoids or retinoids (P ≥ 0.26). Increasing SβC supplementation caused a linear increase in plasma 9-cis-βC (P= 0.04) and tended to cause a linear increase in plasma retinoic acid concentration (P= 0.06)
and a quadratic increase in plasma 13-cis-βC (P = 0.04), 15-cis-βC (P = 0.02), all-trans βC (P = 0.01), and retinyl palmitate (P = 0.04) concentrations; increasing dramatically from SβC1X to SβC5X and then increasing only slightly from SβC5X to SβC10X. In addition, plasma α- cryptoxanthin tended to decrease linearly as SβC concentration increased
(P= 0.06). Plasma zeaxanthin and β-cryptoxanthin did not differ among