THE EFFECTS OF DIETARY TAUROCHOLATE, FAT, PROTEIN, AND CARBOHYDRATE ON THE DISTRIBUTION AND FATE OF DIETARY BETA-CAROTENE IN FERRETS

Dietary beta-carotene has been shown to have cancer chemopreventive ac tion on the basis of epidemiologic evidence and studies in animals. Be cause the anticarcinogenic property of beta-carotene may be exerted pe r se, it is desirable to achieve the maximum absorption and accumulati on of intact p-carotene in various parts of the body. Therefore the ef fects of dietary taurocholate, fat, protein, and carbohydrate on the a bsorption, accumulation, and fate of dietary beta-carotene (3,730 nmol /g diet) in selected tissues of ferrets were explored. Taurocholate (0 .2-1.0% wt/wt) and fat (6-23% wt/wt) caused two- to threefold (p < 0.0 5) increases in the absorption and accumulation of p-carotene in the l iver, lungs, and adipose tissue in a dose-dependent manner. In contras t, neither dietary protein (10-40% wt/wt) nor carbohydrate (25-55% wt/ wt) affected the absorption and accumulation of beta-carotene in vario us tissues. Significantly, taurocholate, 23% fat, or 40% protein also markedly increased the amounts of hepatic retinol and retinyl esters d erived from dietary beta-carotene. These results indicate that dietary taurocholate, fat, and high protein have a marked influence on the ex posure of beta-carotene to intestinal carotene cleavage enzyme or its activity. Thus an ideal combination of dietary components (wt/wt) in f errets for the maximal absorption and accumulation of beta-carotene in different tissues is 0.5% taurocholate and 13.4% fat, whereas 1% taur ocholate, 23% fat, or 40% protein stimulates its conversion to vitamin A.