|ZHU, CHENGHAO - University Of California
Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2013
Publication Date: 5/1/2014
Citation: Lafrano, M.R., Zhu, C., Burri, B.J. 2014. Assessment of tissue distribution and concentration of ß-cryptoxanthin in reponse to varying amounts of dietary ß-cryptoxanthin in Mongolian gerbil. British Journal of Nutrition. 111:968-978 DOI:10.1017/S0007114513003371.
Interpretive Summary: Vitamin A is an essential nutrient, necessary for healthy growth and development. Vitamin A can be formed in the body by several carotenoids. These carotenoids include ß-carotene, a-carotene, and ß-cryptoxanthin. ß-cryptoxanthin is found in citrus fruit such as tangerines and oranges, and other orange and red fruit such as papaya. Not much is known about ß-cryptoxanthin metabolism. This study investigated the whole body metabolism of ß-cryptoxanthin in the Mongolian gerbil. (The Mongolian gerbil is considered the best small animal model of human carotenoid metabolism). We fed gerbils three concentrations of ß-cryptoxanthin: 20, 40 and 60 µg/day, for 21 days. We then measured ß-cryptoxanthin concentrations in blood and in 14 tissues. These tissues included liver, kidney, adipose and intestine. ß-cryptoxanthin was detected in 12 of the 14 tissues, as well as in blood. ß-cryptoxanthin concentrations increased significantly with intake in several tissues, including liver and adipose. However, the increases were nonlinear. These results show that ß-cryptoxanthin is stored in many tissues. This may mean that its functions are widespread.
Technical Abstract: ß-cryptoxanthin is a precursor to vitamin A and has other potential health benefits. However, there is a lack of knowledge regarding its metabolism, storage, and dose-response effects. This study investigated the whole body metabolism of ß-cryptoxanthin in an appropriate small animal model for human provitamin A carotenoid metabolism, the Mongolian gerbil (Meriones unguiculatus). After a 5 day carotenoid depletion period, 5 gerbils were euthanized for baseline values. The remaining gerbils were placed in 3 weight-matched treatment groups (n=8). The groups received either 20 µg/d ß-cryptoxanthin from tangerine concentrate, or 40 and 60 µg/d ß-cryptoxanthin from tangerine concentrate plus pure ß-cryptoxanthin for 21 days. Two gerbils from each treatment group were placed in metabolic cages and had their urine and feces collected during the last two days of the study. Fourteen tissues, including liver, kidney, adipose and intestine were surgically removed and analyzed by reversed-phase HPLC. ß-cryptoxanthin was detected in 12 of the 14 tissues, as well as in blood. ß-cryptoxanthin concentrations increased significantly in several tissues with increasing intake, including liver and adipose. The increases were nonlinear, suggesting that an active transport mechanism may be involved. Vitamin A concentrations were elevated at the start of the study due to a pre-study diet that contained a high concentration of vitamin A. ß-cryptoxanthin maintained those concentrations throughout the study. These results indicate that ß-cryptoxanthin is stored and metabolized in many tissues, potentially indicating that its functions are widespread.