THE ROLE OF BORON IN NUTRITION AND METABOLISM

A large number of responses to dietary boron occur when the boron cont ent of the diet is manipulated. Numerous studies suggest that boron in teracts with other nutrients and plays a regulatory role in the metabo lism of minerals, such as calcium, and subsequently bone metabolism. A lthough the mechanism of action has not been defined, it may be mediat ed by increasing the concentration of steroid hormones such as testost erone and beta-oestradiol. Boron is obtained from a diet rich in fruit s, vegetables, nuts and legumes. The daily intake has been estimated t o range from 0.3 - 41 mg per day. The wide range is due to the variati on of the analytical methods used and differences in the soil content of boron. Based on a limited number of studies, increasing dietary bor on results in increases in the boron concentration of all tissues. Lar ge amounts of boron are well tolerated while consistent signs of defic iency include depressed growth and a reduction in some blood indices, particularly steroid hormone concentrations. Via its effect on steroid hormones and interaction with mineral metabolism, boron may be involv ed in a number of clinical conditions such as arthritis. Further resea rch is required before boron is accepted as an essential nutrient for humans.