Effect of genotype on micronutrient absorption and metabolism: a review of iron, copper, iodine and selenium, and folates.

For the majority of micronutrients, there are very little data, or none at all, on the role of genetic polymorphisms on their absorption and metabolism. In many cases, the elucidation of biochemical pathways and regulators of homeostatic mechanisms have come from studies of individuals that have mutations in certain genes. Other polymorphisms in these genes that result in a less severe phenotype may be important in determining the natural range of variation in absorption and metabolism that is commonly observed. To illustrate some of these aspects, I briefly review the increased understanding of iron metabolism that has arisen from our knowledge of the effects of mutations in several genes, the role of genetic variation in mediating the nutritional effects of iodine and selenium, and finally, the interaction between a genetic polymorphism in folate metabolism and folic acid fortification.