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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #37603
Title: INTESTINAL ABSORPTION AND METABOLISM OF 9-CIS-BETA-CAROTENE IN VIVO: BIOSYNTHESIS OF 9-CIS-RETINOIC ACID

Author
item HEBUTERNE XAVIER - TUFTS-HNRCA
item WANG XIANG-DONG - TUFTS-HNRCA
item JOHNSON ELIZABET - TUFTS-HNRCA
item KRINSKY NORMAN I - TUFTS UNIVERSITY
item RUSSELL ROBERT M - TUFTS-HNRCA

Submitted to: Journal of Lipid Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: There is interest in beta-carotene, a precursor of vitamin A, because it may protect against cancer although how it is broken down in the body is not totally understood. It has recently been shown that a "bent" form of vitamin A has specific and important uses in the body which are different from the more common "straight" form, raising questions about the source of this particular form of vitamin A. This study was done to determine whether the "bent" form of beta-carotene which occurs naturally in foods breaks down into the "bent" form of vitamin A in the bodies of ferrets. "Straight" and "bent" beta-carotene were taken up into the body in similar amounts. In blood and tissues, the "straight" form of beta-carotene was broken down into "straight" vitamin A whereas, the "bent" beta-carotene formed both the "bent" and "straight" forms of vitamin A in similar amounts. This study shows that "bent" beta-carotene present in food breaks down into "bent" vitamin A which is known to activate certain genes which the "straight" form does not. These genes are believed to provide protection from cancer and heart disease.

Technical Abstract: This study was done to examine the intestinal absorption and cleavage of 9-cis-beta-carotene in vivo. A micellar solution, containing either no addition or 10 micro mol of 9-cis or all-trans beta-carotene, was perfused for two hours through the upper portion of the small intestine of ferrets. The effluent of a mesenteric lymph duct cannulation was collected, as well as intestinal mucosa scrapings, a portal blood sample and a liver biopsy, both before and after perfusion. Carotenoids and retinoids were measured by reverse-phase, high performance liquid chroma- tography. 9-cis- and all-trans beta-carotene were transported equally well into mesenteric lymph, although the intestinal concentration of the corresponding isomer was tenfold higher after perfusion of the 9-cis- isomer than after perfusion of all-trans beta-carotene. Regardless of which isomer was used, perfusion of beta-carotene resulted in the biosynthesis of similar amounts of retinoic acid in portal blood, liver and intestine. However, after the perfusion of all-trans-beta-carotene, all the retinoic acid formed was in the all-trans form, whereas the perfusion of 9-cis-beta-carotene resulted in the biosynthesis of about 50% of the total retinoic acid as the 9-cis- isomer. We conclude that in the in vivo ferret model, 9-cis-beta-carotene has a good bioavail- ability and is a precursor of 9-cis-beta-retinoic acid.