Intake Of Dark Green, Leafy Vegetables Enhances Serum Retinol In Children

Nutrition Research Newsletter, Sept, 1999 by Etor E. K. Takyi

Retinol is a fat-soluble vitamin that is essential for various physiological processes and is one of the few vitamins for which both deficiency and excess could cause serious health consequences. Vitamin A deficiency in children usually affects the eyes and is associated closely with protein-energy malnutrition, acute respiratory disease, and diarrhea. In most developing countries, the main source of vitamin A is provitamin A from plant sources due to economical constraints.

A recently completed randomized, double-blind, controlled study was designed to determine if the consumption of dark green, leafy vegetables would enhance the retinol status of preschool children to acceptable levels. Cassava and kapok were the leaves chosen for the study because of their high content of provitamin A and because they are widely used in many developing countries. The study was conducted in Ghana, a country known for frequent food shortages, with greater than 50% of the children classified as being malnourished.

There were five randomly divided groups, with 88 children per group between the ages of 2.5-6 years. The main meal was the same for all five groups, primarily consisting of rice, yams, gari, and beans. A different stew was prepared for each group, using home-cooking practices and common ingredients, so the parents of the children would be able to prepare the stew if the study was successful. The stews differed in the levels of fat and [Beta]-carotene provided. The researchers examined serum retinol levels, anthropometric measurements, hemoglobin, pre-albumin, retinol-binding protein, worm infestation, and level of infection, prior to and after completion of the study.

There were significant differences found in the percentages of children with deficient, low, and adequate levels of serum vitamin A before and after the feeding period. The percentage of children with adequate retinol status increased from 28.2% to 48.2% after the feeding. Consumption of dark green, leafy vegetables with fat (10 g/100 g) significantly enhanced serum retinol. There was a significantly lower incidence of chronic infection during the post-feeding period. The astonishingly high incidence of anemia (92%) was unfortunately not decreased during the feeding phase of the study.

The study was successful in demonstrating that a food-based intervention could enhance vitamin A levels. Increased consumption of the leaves used in this study could help prevent the incidence of vitamin A deficiency in developing countries.

Etor E. K. Takyi, Children's Consumption of Dark Green, Leafy Vegetables with Added Fat Enhances Serum Retinol, J Nutr 129:1549-1554 (August 1999) [Correspondence: Etor E. K. Takyi, Nutrition Unit, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana.]