Vitamin A thwarts malaria in children.

Regular doses of vitamin A hold off many cases of malaria in children, particularly those ages 1 to 3, new research shows. These findings suggest that the vitamin bolsters the immune system's fight against the mosquito-borne disease.

Vitamin A is known to boost production of macrophages, T cells, and antibodies--all immune system stalwarts. To gauge its effects against the parasite that causes malaria, U.S. scientists teamed with researchers at the Papua New Guinea Institute of Medical Research in Goroka to track 480 children in that country.

Every 3 months for 13 months, half the children received an inert substance; the rest got a capsule containing 200,000 international units of vitamin A, which the liver stores and parcels out as needed.

Subsequent medical examinations and blood tests of the children, ages 6 months to 5 years, revealed that those getting the placebo experienced 249 episodes of fever that were accompanied by a substantial presence of malarial parasites in the blood. In contrast, the children getting vitamin A supplements suffered only 178 such episodes. The study appears in the July 17 LANCET.

Children less than a year old gained little benefit from the vitamin A, but such babies don't usually become as ill with malaria as do children 1 to 3 years old. Vitamin A imparted significant resistance to the disease to these toddlers, says study coauthor Anuraj H. Shankar of Johns Hopkins Medical Institutions in Baltimore.

Of 90 such children getting the placebo, 67 (74 percent) had enlarged spleens, a frequent complication of malaria. Only 46 (58 percent) of 79 children this age getting vitamin A had the condition.

By age 5 or 6, many children in the tropics have built partial resistance to malaria. The children ages 1 to 3 getting vitamin A exhibited an immune response against the disease resembling the response normally seen in their older siblings. "This appears to accelerate the acquisition of [some] immunity by a few years," Shankar says.

The vitamin helped deter mild and moderate disease rather than the most severe illness. Equal numbers of children in the two groups had harsh cases of malaria. Vitamin A may not affect the mechanism in the body that controls susceptibility to high concentrations of parasites, and hence, severe disease, says James W. Kazura of Case Western Reserve University in Cleveland.

Nevertheless, at pennies per capsule, vitamin A may prove to be a useful weapon against the most common malarial infections, he says.