Twice the amount of α-carotene isolated from carrots is as effective as β-carotene in maintaining the vitamin A status of Mongolian gerbils

The vitamin A (VA) value of carotenoids from fruits and vegetables is affected by many factors. This study determined the VA value of a-carotene isolated from carrots compared with beta-carotene and retinyl acetate supplements fed to Mongolian gerbils (Meriones unguiculatus). Gerbils (n = 38) were fed a VA-free diet for 4 wk. At baseline, 6 gerbils were killed to determine liver VA. Gerbils were divided into 3 treatment groups (n = 9/group) and given 35, 35, or 17.5 nmol retinyl acetate, a-carotene or P-carotene, respectively, in 2 divided doses 5 h apart each day. The remaining 5 gerbils received oil vehicle. Gerbils were killed after 3 wk of supplementation. Serum samples and livers were collected and analyzed for VA. Liver extracts were subsequently saponified to quantify a-retinol. Serum retinol concentrations did not differ among the groups. Liver retinyl palmitate concentrations were significantly higher in the retinyl acetate treatment group (0.198 +/- 0.051 mu mol/g; P < 0.05) than in all other groups. The alpha- and beta-carotene treatments resulted in similar retinyl palmitate concentrations, i.e., 0.110 +/- 0.026 and 0.109 +/- 0.051 mu mol/g, respectively, which did not differ from the concentrations in gerbils killed at baseline (0.123 +/- 0.024 mu mol/g). The oil group had significantly less retinyl palmitate (0.061 +/- 0.029 [mu mol/g; P < 0.05) than all other groups. alpha-Retinol was detected in livers of the a-carotene group (0.062 +/- 0.013 mu mol/g). Thus, twice the amount of purified a-carotene maintained VA status as well as beta-carotene in VA-depleted gerbils. Conversion factors were similar to 5.5 kg alpha-carotene or similar to 2.8 mu g P-carotene to 1 mu g retinol.