Vitamin A Cuts Children's Malaria Risk by Nearly a Third

Scientists have shown that when young children in New Guinea were given vitamin A supplements, they had 30 percent fewer malaria attacks and the number of malaria parasites in their blood dropped by 36 percent. The study appeared in the July 17, 1999 issue of The Lancet.

The parasite Plasmodium falciparum (Pf) causes 400 million malaria cases and 2.5 million deaths worldwide every year. In the part of New Guinea where the current study was carried out, approximately 55 percent of preschool children carry the Pf parasite, and malaria is the most frequent cause of death among that age group. Past studies examining the relationship between vitamin A and malaria were not conclusive; this study was the first specifically designed to examine whether vitamin A can bolster the body's resistance to malaria.

Lead author Anuraj H. Shankar, DSc, International Health, Johns Hopkins School of Public Health, said, "The 30 percent reduction in malaria episodes associated with vitamin A approaches levels of protection seen with insecticide-treated bed nets, and exceeds protective levels of field-tested experimental malaria vaccines." Dr. Shankar added, "Nutrient-based interventions may have an important role in malaria control alongside bed nets and future vaccines. We need all the help we can get against this disease." At three cents per dose, vitamin A supplements would rank among the most cost-effective nonpharmacologic interventions for malaria.

Dr. Shankar and a team of scientists from the Papua New Guinea Institute of Medical Research followed 480 children between the ages of six and 60 months for one year. The children were randomly assigned to groups that received high-dose vitamin A or a placebo every three months for 13 months. The researchers tallied children's clinical episodes of malaria sickness. By the end of the 13-month study, children who had received vitamin A had a 30 percent reduction in clinical episodes and a 36 percent reduction in Pf levels in the blood. Interestingly, the effects were most apparent in children between 12 and 36 months of age. This group, normally experiencing the highest malaria sickness rate, had 35 percent fewer malaria attacks, 68 percent lower levels of parasites in their blood, and 26 percent fewer enlarged spleens, a common result of malaria.

No statistically significant differences were detected between the two groups in the percentages of children who got infected with the malaria parasite, or in children's rates of anemia. Also, although vitamin A did reduce the overall number of malaria attacks, it did not prevent the most intense attacks accompanied by very high parasite levels.

"This study highlights the complex nature of the body's resistance to Pf," said Dr. Shankar. "The fact that vitamin A conferred an overall 30 percent reduction but was not effective against severe infections may imply that vaccines against malaria will have to stimulate several different factors in order to provide broad protection. Understanding how nutrients influence resistance to malaria and other diseases will be of great benefit."

Support for this study was provided by Cooperative Agreements between the Johns Hopkins School of Public Health and the Office of Health and Nutrition, U.S. Agency for International Development (USAID), and a grant to the Papua New Guinea Institute of Medical Research from the Australian Agency for International Development (AusAID).