Trace Elements in Human Nutrition

This chapter emphasize those elements for which human studies are available, namely iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), selenium, chromium, molybdenum, and iodine. Calcium (Ca) could be a practical problem for Fe absorption by humans, particularly for those taking Ca supplements; however, the dietary intakes of Zn required to inhibit Fe utilization in experimental animals are much higher than those found in normal human diets. Animal and epidemiological studies suggest that high intakes of Zn, combined with low intakes of Cu, adversely affect cholesterol metabolism; however, the impact on human health is difficult to assess. Zinc interference with Cu absorption has been demonstrated in animals and Cu deficiency has been observed in human subjects receiving Zn supplements. In the absence of widespread Mn deficiencies in normal human populations, its practical significance in human nutrition is difficult to assess.