For children with low stores of two brain-power nutrients, supplements may have different, and complex, effects, a new clinical trial suggests.
Iron deficiency is the most common nutritional deficiency worldwide, affecting about 2 billion people, according to the World Health Organization. Poor children in developing countries are at particular risk for shortfalls in iron, as well as other nutrients, including omega-3 fats found largely in oily fish.
The new study looked at the effects of giving 321 schoolchildren in South Africa either supplements containing iron, omega-3s or both. All of the children had low levels of both nutrients, which are vital for children's growth and healthy brain development.
After about eight months, researchers found varied changes in the kids' memory and learning abilities.
In general, children given iron showed improvements on tests of memory and learning. That was especially true if they had full blown anemia, a disorder wherein the blood's oxygen-carrying capacity is reduced, causing symptoms such as fatigue and difficulty with concentration and memory.
In contrast, there was no overall benefit linked to omega-3 supplements. And when the researchers zeroed in on kids with anemia, those who used omega-3s did worse than before on one test of memory.
Among the children with clear iron deficiency, but not yet anemia, girls who got omega-3s fared worse, while boys improved their test scores.
What it all means for kids with nutritional deficiencies is unclear, according to the researchers from North-West University in Potchefstroom, South Africa, and the results need to be interpreted cautiously.
The children in this study were 6 to 11 years old. However, animal research suggests brain deficits that take shape early in life might not be reversible. It's possible, then, that supplementation during school age might be too late to achieve beneficial effects on cognitive performance.
Still, the omega-3 findings are consistent with recent animal research. Rats deficient in both iron and omega-3s, giving either supplement alone seemed to worsen the animals' memory performance. The picture was better, though, when the rats were given both iron and omega-3s.
In children, things are more complicated. Other nutritional deficiencies, as well as exposure to toxins like lead and the general effects of poverty could all dampen kids' brain development, the researchers pointed out.
Since this study focused on impoverished children with low iron, and possibly other nutritional deficiencies, the results cannot be extended to children in general. In the U.S., recommendations call for babies to get an iron test during the first year of life to check for deficiencies. For healthy kids older than six months, the recommended iron intake varies from 7 to 15 mg of iron per day, depending on their age and sex.
There is a risk from getting too much iron; parents should ask their doctor before giving children iron supplements.
SOURCE: American Journal of Clinical Nutrition, online October 24, 2012.
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