Mouth swab detects zinc deficiency

Newly discovered biomarkers allow for accurate measurement of human zinc by a simple blood test or mouth swab. Zinc deficiency is a worldwide problem, especially in developing countries where many people have limited access to good sources of the mineral, such as red meat. Signs of zinc deficiency are often skin rashes and infections. “The method could be used in developing countries, and here in the US, to re-examine populations for adequate zinc status,” says Bob Cousins, an eminent scholar in nutritional biochemistry at the University of Florida. “When children are supplemented with zinc, their quality of life dramatically increases,” he says. “Their stature increases, their ability to learn increases, and they can better fight off infections that lead to things like diarrhea.” To find the biomarkers, the researchers performed genetic analysis on human subjects at the beginning of the study, when the subjects were low in zinc due to an experimental diet they were fed, and when the subjects returned to normal zinc levels. The genetic analysis was done using devices called microarrays that allowed for the examination of each subject’s entire genome, or every gene in their body, in response to changing zinc levels. Of the tens of thousands of genes analyzed, the researchers identified eight that changed with zinc levels and thus could be used as zinc biomarkers. “We really need to understand the underlying biochemistry and regulation of human micronutrients,” says Roger Sunde, professor of nutritional sciences at the University of Wisconsin-Madison and a longtime researcher of biomarkers for selenium, another important element for human health. “And we really need to have the full complement of tools to know whether someone is adequate in all of the nutrients.” Once a zinc deficiency is detected using the biomarkers, it can be easily corrected in a cost-effective manner using supplements, says Moon-Suhn Ryu, a former doctoral student in UF’s food science and human nutrition department’s nutritional sciences program and lead author of the study, published in Proceedings of the National Academy of Sciences. “Additionally, our findings will let people who are involved in policy design or epidemiological studies identify communities that will benefit from improved zinc nutrition,” Ryu says. The recommended dietary allowances of zinc for men and non-pregnant and non-lactating women over age 19 are 11 milligrams and eight milligrams, respectively. In addition to red meat, other good sources of zinc include oysters, poultry, beans, and zinc-fortified breakfast cereal. The research was funded in part by the National Institutes of Health.