|Smith jr, James|
Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/2/1996
Publication Date: N/A
Citation: Interpretive Summary: People with low intakes of meat and dairy products can be at risk of both vitamin A and zinc deficiency. Vitamin A can be obtained from carotenoids in fruits and vegetables, but the conversion process is not very efficient and may be affected by the amount of vitamin A stored in the liver. Zinc is considered to be required for the release of vitamin A from the liver into the blood, but whether the conversion of carotenoids to vitamin A is affected by zinc status is unknown. As part of ongoing studies of interactions of vitamin A and zinc metabolism, carotenoids have been measured in serum of 513 children 5-7 years old in Belize, Central America. Although concentrations of some carotenoids have been reported for adults, very little information is available for children, particularly for carotenoids other than beta-carotene, the most widely studied of dietary carotenoids. This paper provides baseline information on concentrations of lutein/zeaxanthin, lycopene, a-cryptoxanthin, and a- and b-carotene for a larger number of children than previous surveys. Predominant carotenoids in the blood were lutein/zeaxanthin and b-carotene. Since reproducibility of serum carotenoid measurements in children has not been previously reported, blood samples were collected from a subset of 23 children two weeks after the first sample. Results of the analyses of the second samples agreed very well with the results of the first sample. These studies will contribute to the alleviation of vitamin A deficiency and to a better understanding of zinc-vitamin A interactions.
Technical Abstract: Suggestions that carotenoid-containing foods are beneficial in maintaining health have led to a number of studies of carotenoid concentrations in plasma/serum of adults. Since few data are available for children, we report serum carotenoid concentrations of approximately 500 children of Belize, Central America. Carotenoid concentrations were determined as part of a survey of vitamin A status of children, most between 65 and 89 months Reproducibility of the concentrations was tested by collecting a second blood sample two weeks after the first collection from a subset of children (n=23) who consumed their habitual diet with no treatment during the interim. The predominant serum carotenoids were lutein/zeaxanthin and b- carotene, which accounted for 27% and 23% of total carotenoids, respectively. The sum of the three pro-vitamin A carotenoids, a- and b- carotene and b-cryptoxanthin, constituted 51% of total carotenoid concentration. Partial correlations of each carotenoid with fasting retino concentration indicated that b-carotene had the highest correlation. Concordance correlation coefficients (rc) for fasting carotenoid concentrations determined two weeks apart were greater than or equal to 0.89 for lycopene, b-cryptoxanthin, a- and b-carotene. The rc for lutein/zeaxanthin and total carotenoids was lower, 0.59 and 0.68, respectively, due to higher lutein/zeaxanthin concentrations at the second sampling than at the first. The data represents the largest number of serum carotenoid concentrations of children reported to date. The reproducibility of the concentrations suggests both that individuals have characteristic profiles and that serum carotenoid concentrations can be measured randomly over at least a two-week period without significant bias.