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Providing perspectives on recent research into vitamins and nutritionals


Are Kids’ Vitamin A Intakes Adequate? Diverse Surveys Compared

By Julia Bird

Two recent publications from the journal Public Health Nutrition looked at vitamin A intakes in children.

The first study investigated the relationship between vitamin A intakes and how well they correlate with circulating levels of vitamin A levels in preschoolers in the context of infection in Zambia. The authors Hotz et al. report on the results of a cross-sectional cluster-designed survey in a rural population. The staple food iswhite maize, which contains very little vitamin A activity. Vitamin A can be obtained pre-formed as retinol from mainly meat sources, or can also be converted from pro-vitamin A carotenoids such as alpha- and beta-carotene, and beta-cryptoxanthin in vegetable-based foods. The retinol equivalency of carotenoids is normally assumed to be 12:1 from beta-carotene and 24:1 from other pro vitamin A carotenoids, although other studies show that this may be higher for some sources. Classical plant breeding techniques have produced a maize variety rich in beta-carotene, or orange maize, that has a high vitamin A activity. The survey was conducted as preparation for an intervention using orange maize in Zambia. Young children are at risk of vitamin A deficiency due to their high rate of growth.

The authors found that over half of children had vitamin A levels indicating deficiency. In addition, 61% showed signs of acute infection, and 16% had malaria parasites. Protein, fat and energy intakes were adequate in general, and vitamin A intakes appeared to be adequate despite biochemical tests that show deficiency. From analyzing sources of vitamin A, it appears that 79% came from vegetables, roots and tubers, particularly pumpkin, seasonal leafy greens and yellow sweet potato. Intakes were higher around the harvest season. Out of the harvest season, mangoes were a significant source of vitamin A. The authors found an association between vitamin A intakes and circulating levels of vitamin A when a retinol equivalency of 26:1 was assumed. The rates of functional deficiency may relate to poor conversion from carotenoids, or the effects that infection have on vitamin A levels.

O’Neil and colleagues also report on nutrient levels in children, in a relatively well-nourished and health US population. They used data from NHANES, a representative, ongoing and cross-sectional survey of nutrition and health. Most preschoolers met the Estimated Average Requirement (EAR) for vitamin A intakes, however in older age groups, around one quarter of 6-12 year olds did not meet the EAR, and over half of teenagers did not meet the EAR. Fruit juice non-consumers had higher rates of not meeting the EAR and are therefore are at a greater risk of deficiency.

Both these studies show the importance of providing enough bioavailable vitamin A in the diets of children, both in developing and developed countries.

Main references:

Hotz C, Chileshe J, Siamusantu W, Palaniappan U, Kafwembe E. Vitamin A intake and infection are associated with plasma retinol among pre-school children in rural Zambia. Public Health Nutr. 2012 Mar 23:1-9. [Epub ahead of print]

O'Neil CE, Nicklas TA, Zanovec M, Kleinman RE, Fulgoni VL. Fruit juice consumption is associated with improved nutrient adequacy in children and adolescents: the National Health and Nutrition Examination Survey (NHANES) 2003-2006. Public Health Nutr. 2012 Mar 23:1-8. [Epub ahead of print]