Twice the amount of alpha-carotene isolated from carrots is as effective as beta-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 alpha-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, alpha-carotene or beta-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 alpha-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 micromol/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 micromol/g, respectively, which did not differ from the concentrations in gerbils killed at baseline (0.123 +/- 0.024 micromol/g). The oil group had significantly less retinyl palmitate (0.061 +/- 0.029 micromol/g; P < 0.05) than all other groups. alpha-Retinol was detected in livers of the alpha-carotene group (0.062 +/- 0.013 micromol/g). Thus, twice the amount of purified alpha-carotene maintained VA status as well as beta-carotene in VA-depleted gerbils. Conversion factors were approximately 5.5 microg alpha-carotene or approximately 2.8 mug beta-carotene to 1 microg retinol.
Tanumihardjo
Sherry A
SA
Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA. sherry@nutrisci.wisc.edu
Howe
Julie A
JA
D000818:Animals; D002338:Carotenoids / Q000008:administration & dosage* / Q000032:analysis / Q000097:blood / Q000302:isolation & purification*; D018552:Daucus carota / Q000737:chemistry*; D004032:Diet; D004224:Diterpenes; D005849:Gerbillinae; D007700:Kinetics; D008099:Liver / Q000737:chemistry; D008297:Male; D009752:Nutritional Status; D000084562:Retinyl Esters; D014801:Vitamin A / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000032:analysis* / Q000097:blood / Q000378:metabolism; D015430:Weight Gain; D019207:beta Carotene / Q000008:administration & dosage*
D004224:Diterpenes; D000084562:Retinyl Esters; D019207:beta Carotene; D014801:Vitamin A; C014794:retinol palmitate; D002338:Carotenoids; C041635:alpha-carotene