Missing Micronutrients - How Best To Nourish A Child?

Scientists discussed the merits of "animal source foods" such as meat and milk as well as other approaches to diet supplementation and fortification during the annual meeting of the American Association for the Advancement of Science (AAAS).

"The diets of the poor are largely cereal-based, monotonous and lacking in diversity and micronutrients," said Montague Demment, director of the Global Livestock Collaborative Research Support Program, an effort funded by the U.S. Agency for International Development that involves scientists from a dozen U.S. universities and 60 foreign institutions. "In the modern world, we need to figure out how to get nutrients into people and do it in the proper context," he said.

There is a link between good nutrition and how well children develop, both in mind and body, according to Demment. Their school performance, in turn, can have a strong influence on the growth of their nation's economy. Sound nutrition helps ultimately to fuel national development, he said.

Biofortification, which uses conventional plant breeding techniques to increase the level of micronutrients in crops, is one possibility. It is a relatively new strategy. There are no definitive studies yet that show the impact of such nutritionally improved varieties on children, according to Howarth Bouis of the International Food Policy Institute. Initial results do suggest, however, that wide use of biofortified crops could significantly increase iron and zinc intake in poor people's diets. Research is underway to determine if those nutrients can be readily absorbed by humans.

Experts say major nutrition education programs will have to be mounted to encourage consumers to switch to certain varieties of biofortified crops, particularly if there are changes in color, appearance or texture as a result.

Some field studies already have been done on the efficacy of adding meat in a systematic way to the diets of children in developing nations. In a two-year study in rural Kenya, completed in 2003, scientists supplemented the usual corn- and bean-based lunches of several hundred school children with meat, milk or an equivalent amount of energy from vegetable oils.

Children in all three groups, whether they received meat, milk or oil, gained about 400 grams more weight and increased their upper-arm muscle mass compared to classmates who received no supplements. But the children who received the 68-gram meat supplement (2 ounces) also performed significantly better than all the groups on a test of problem-solving ability and fluid intelligence, said Lindsay H. Allen, director of the U.S. Agricultural Research Service's Western Human Nutrition Research Center, Davis, California.

The research in Kenya also found that either meat or milk supplements greatly improved the vitamin B-12 status of the children, reducing the prevalence of the deficiency to about 10 percent in the treated groups compared to 50 percent in the general school population. The 68 grams of meat provided 106 percent of a child's B-12 requirement, 68 percent of the zinc requirement, and 26 percent of the iron, Allen said.

The results were consistent with earlier observational studies in Kenya, Egypt and Mexico which suggested that children might benefit from some changes in their diets. In Kenya, scientists found that animal source foods, especially meat products, are consumed by less than 14 percent of children and usually in small amounts (less than 17 grams a day). While international aid agencies often address the lack of micronutrients in diets by providing supplements as a quick fix, some scientists argue that use of animal source foods, such as meat and milk, can be just as effective while also promoting the development of local sources of animal food production.

The recent research builds on studies during the 1980s and early 1990s that showed the quality of the diet - whether it contained animal source foods - was a better predictor of nutritional status than the quantity of food consumed. Although the "green revolution" greatly expanded access to cereals as a cheap and available sources of energy, it also has had a downside, according to Montague Demment, as cereals became abundant and cheap.

Both Demment and Allen argue that use of animal source foods should be given more attention. In an era when the consumption of such foods continues to rise globally, Allen says, "the challenge is to ensure that the billions of poor who do not currently consume adequate amounts can improve their access to these foods. To ignore this problem is to ignore the tremendous loss of human capital that results from the subsequent micronutrient deficiencies."