Overlapping vitamin A interventions in the United States, Guatemala, Zambia, and South Africa: case studies

Abstract

Vitamin A (VA) deficiency is a serious public health problem, especially in preschool children who are at risk of increased mortality. In order to address this problem, the World Health Organization recommends periodic high-dose supplementation to children 6-59 months of age in areas of highest risk. Originally, supplementation was meant as a short-term solution until more sustainable interventions could be adopted. Currently, many countries are fortifying commercialized common staple and snack foods with retinyl palmitate. However, in some countries, overlapping programs may lead to excessive intakes. Our review uses case studies in the United States, Guatemala, Zambia, and South Africa to illustrate the potential for excessive intakes in some groups. For example, direct liver analysis from 27 U.S. adult cadavers revealed 33% prevalence of hypervitaminosis A (defined as ≥1 μmol/g liver). In 133 Zambian children, 59% were diagnosed with hypervitaminosis A using a retinol isotope dilution, and 16% had ≥5% total serum VA as retinyl esters, a measure of intoxication. In 40 South African children who frequently consumed liver, 72.5% had ≥5% total serum VA as retinyl esters. All four countries have mandatory fortified foods and a high percentage of supplement users or targeted supplementation to preschool children.

Keywords: Guatemala; South Africa; United States; Zambia; excessive vitamin A intake; fortification; hypervitaminosis A; supplementation.

Figure 1.

Fluid milk sales in the United States have fallen in the past decade. Considering that low-fat and skim milks are fortified, we hypothesize that this may affect vitamin A intakes, particularly among low-income groups who do not receive free milk through the Special Supplemental Nutrition Program for Women, Infants, and Children. Low-income pregnant U.S. women qualifying for such a program had 9% prevalence of vitamin A deficiency.

Figure 2.

The prevalence of vitamin A deficiency (<0.1 μmol/g liver) and hypervitaminosis A (≥1.0 μmol/g liver) in U.S. adult cadavers (n = 27, aged 49–101 years) who were diagnosed using liver autopsy samples.

Figure 3.

Stratification of liver vitamin A concentrations (in μg retinol/g liver in the original paper) in a survey of Guatemalan liver samples collected during autopsy of children and adults from 1975 to 1977. During this timeframe, the prevalence of low values (<50 μg retinol/g liver) decreased (black), while hypervitaminotic values (≥ 300 μg retinol/g (red)) increased slowly. The areas in light and dark green represent optimal vitamin A status (50–150 μg retinol/g). The current values recommended to be used are <0.1 μmol/g liver for vitamin A deficiency, which is equivalent to 29 μg retinol/g and ≥1.0 μmol/g liver for hypervitaminosis A, which is equivalent to 290 μg retinol/g.

Figure 4.

A cross-sectional study was performed in South African preschool children to evaluate serum retinol concentrations 3–4 weeks after a vitamin A supplementation campaign. Circulating serum retinyl esters as a percent of total serum vitamin A were determined in a subset of the children who met inclusion criteria of combined high liver consumption and having received a high-dose vitamin A supplement during the campaign.