People lose the ability to detect the taste of iron in drinking water with advancing age, raising concern that older people may be at risk for an unhealthy over-exposure to iron, scientists are reporting in results they term "unique." The study appears in the ACS' journal Environmental Science & Technology.
Andrea Dietrich, Susan Mirlohi, and Susan Duncan and colleagues point out that perception of a metallic flavor in water can help people limit exposure to metals such as iron, which occurs naturally in water or from corrosion of iron water-supply pipes. Although commonly referred to as "metallic taste," iron and other metals actually produce both a taste and an odor; this combination is a flavor. People need less iron after age 50. And studies suggest that older people who consume too much — especially in dietary supplements and iron-rich foods — may be at increased risk for Alzheimer's disease and other age-related conditions. Scientists long have known that taste sensory perception fades with age. Dietrich's group set out to fill in gaps in knowledge about how aging affects perception of a metallic flavor in water.
Their results with 69 volunteers aged 19 to 84 years identified a distinctive age-related decline in ability to taste iron. People over age 50 tended to miss the metallic taste of iron in water, even at levels above the thresholds set by the U. S. Environmental Protection Agency and the World Health Association. "Our findings are unique in that drinking water is the source of the environmental sensory contaminant and evidence is provided for wide variation in the human population," the report states. "Whereas our research focused on iron, there are implications for other metals of health concern, most notably copper from copper pipes as our previous research has demonstrated that copper is less flavorful than iron and it is known that copper is also more toxic than iron."