Boron in human and animal nutrition

This review describes the findings from human and animal studies indicating that B is a dynamic trace element which, in physiological amounts, can affect the metabolism or utilisation of numerous other substances involved in life processes including macrominerals, energy substrates such as triglycerides and glucose, nitrogen containing substances such as amino acids and proteins, reactive oxygen species, and estrogen. Through these effects, B can affect the function or composition of several body systems, including the brain, skeleton and immune system, generally in a beneficial fashion. Moreover, homeostatic mechanisms apparently exist for B because it is rapidly excreted in the urine, does not accumulate in tissues, and is maintained in a relatively narrow range of concentrations in blood of healthy individuals. Thus, even though B has not been conclusively established as essential because a biochemical function for it has not been identified, its beneficial actions suggest that an intake of over 1 mg day^-1 (but probably not more than 13 mg day^-1) is desirable; diets low in fruits, vegetables, legumes and nuts may not provide this amount of B. Boron may be of more practical nutritional importance than currently acknowledged.