Boost Immunity, Not Disease
Take your vitamins.
A great many children are familiar with that parental command, and with good reason. Eliminating vitamin and other micronutrient deficiencies among children is one of the easiest ways to improve public health.
But public health researchers increasingly recognize that the effects of micronutrient supplements can be complex and sometimes unexpected. A recent trial in Tanzania found that iron folate supplements, compared to a placebo, caused about 12 percent more hospital admissions or deaths among local children over a 2-year period—apparently by increasing their susceptibility to malaria.
“A micronutrient might help boost a child’s immunity, but if it is given during acute illness, it might in some cases also empower an infectious organism,” explains infectious disease epidemiologist Christian Coles. “Thus, when bloodstream levels of a micronutrient go down during an infection, it isn’t necessarily a bad thing. The body might be sequestering the micronutrient to keep it away from the microorganism, or to improve its ability to fight off infection.”
“We need to know more about the effects of nutrients on infectious diseases and children’s immune responses.” —infectious disease epidemiologist Christian Coles
Overall, micronutrient supplementation is usually beneficial in nutrient-deficient children. But the effects can differ strikingly from one population to the next, for reasons that are not clear. “One big challenge we now face is to uncover the biological details of what’s producing these effects,” Coles says.
Coles is currently working on a study in Bangladesh that is attempting to get at some of these biological details: Newborns admitted to the hospital with bacterial bloodstream infections are given vitamin A supplements or a placebo. Coles and his colleagues are measuring the resulting duration and severity of illness, and also are taking blood samples to assess the effects of vitamin A on key markers of the immune response. “We want to see whether these are changed by the treatment and thus might be driving any positive health effects,” he says.
A related set of challenges has to do with finding the populations that can benefit most from micronutrient supplements. “Twenty years ago these micronutrient deficiencies were termed ‘hidden hunger’ because clinically they weren’t always obvious; and unfortunately they’re still largely hidden,” says epidemiologist Keith P. West, Jr. With the help of a recent grant from the Gates Foundation, West and his colleagues are working to develop quick, “field-friendly” methods for assessing multiple micronutrient levels in blood samples. By making research easier, such methods could eventually enable a significant expansion of micronutrient deficiency control efforts worldwide.