BIOCHEMICAL EFFECTS OF PHYSIOLOGICAL AMOUNTS OF DIETARY BORON

Research on human and animal boron nutrition has progressed sufficient ly over the past decade to develop working hypotheses for biochemical roles of the element. II is well established that Vascular plants, dia toms, and some species of marine algal flagellates have acquired an ab solute requirement for boron although the primary role remains unknown . Discovery of naturally-occurring boron oxy compounds, all ionophoric macrodiolide antibiotics with a single boron atom critical for activi ty, established at least one biochemical role of boron. Recent finding s suggest that physiological amounts of supplemental dietary boron (PS B) affect a wide range of metabolic parameters in chick and rat model systems as well as humans. Cholecalciferol (vitamin D-3) regulates ene rgy substrate utilization; current findings indicate that boron modifi es that regulatory function. For example, in chicks, PSB substantially corrected vitamin D-3-deficiency-induced elevations in plasma glucose concentrations. Boron also alleviates perturbations in mineral metabo lism characteristic of vitamin D-3 deficiency. In rachitic chicks, PSB alleviated distortion of the marrow sprouts in the proximal tibial ep iphysial plate. Boron may help prevent inflammatory disease as several key regulatory enzymes in the inflammatory response are inhibited by PSB. The findings to date support the hypothesis that boron is essenti al for animals and humans. Also, boron and vitamin D-3 have the same o verall effect on the utilization of energy substrates found in plasma. Further advances in boron nutrition research will probably include ch aracterization of the mechanisms through which boron modulates immune function, insulin release, and Vitamin D metabolism. (C) 1997 Wiley-Li ss, Inc.