Biochemical effects of physiological amounts of dietary boron

Research on human and animal boron nutrition has progressed sufficiently over the past decade to develop working hypotheses for biochemical roles of the element. It is well established that vascular plants, diatoms, and some species of marine algal flagellates have acquired an absolute 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 activity, established at least one biochemical role of boron. Recent findings suggest that physiological amounts of supplemental dietary boron (PSB) affect a wide range of metabolic parameters in chick and rat model systems as well as humans. Cholecalciferol (vitamin D3) regulates energy substrate utilization; current findings indicate that boron modifies that regulatory function. For example, in chicks, PSB substantially corrected vitamin D3-deficiency-induced elevations in plasma glucose concentrations. Boron also alleviates perturbations in mineral metabolism characteristic of vitamin D3 deficiency. In rachitic chicks, PSB alleviated distortion of the marrow sprouts in the proximal tibial epiphysial 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 essential for animals and humans. Also, boron and vitamin D3 have the same overall effect on the utilization of energy substrates found in plasma. Further advances in boron nutrition research will probably include characterization of the mechanisms through which boron modulates immune function, insulin release, and vitamin D metabolism.