Trace Mineral Losses in Sweat

Copper, iron and zinc are nutritionally essential trace minerals that confer vital biological roles including the maintenance of cell structure and integrity, regulation of metabolism, immune function, oxygen transport, and muscle and central nervous system function. Dietary Reference Intakes (DRIs) for these minerals are useful for the general population, but these guidelines may be inadequate for some populations (e.g., soldiers, athletes) who experience copious sweating due to high physical activity levels and/or frequent exposure to extreme environmental conditions. The trace mineral content of sweat may predispose these populations to subclinical/clinical nutritional deficiencies. Studies on sweat trace mineral losses report highly variable results. Much of the variability may be methodological. Non-standardization of collection techniques, collection sites (local versus whole body), and numerous other variables cloud definitive conclusions on sweat trace mineral losses. The objectives of this manuscript are to 1) review the literature on sweat copper, iron, and zinc losses, 2) present the potential sources of variability, 3) interpret findings in relation to nutritional needs, and 4) identify directions for future research.