Submitted to: Recommended Dietary Allowances Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/1995
Publication Date: N/A
Technical Abstract: There is considerable evidence for the existence of a metabolic insulin- vitamin D axis which, in turn, is under the reciprocal influence of both components. The axis is important for regulation of energy substrate utilization and mineral metabolism. To characterize further the apparent influence of boron on the axis, especially pronounced during concomitant marginal vitamin D deficiency, plasma 1,25 vit D concentrations and peak insulin secretion from isolated perfused pancreata were determined in an experiment with a fully crossed two-factor design. Day-old cockerel chicks (20 per group) were fed a ground corn, high protein casein and corn oil based diet (approx. 0.29 mg B/kg) supplemented with boron at 0 or 1.36 mg/kg and vitamin D3 at 125 (inadequate; IVD) or 625 (adequate; AVD) IU/kg. At 40 d of age, an interaction between boron and vitamin D affected (p<0.002) plasma 1,25 vit D concentrations. In IVD chicks, boron markedly improved plasma 1,25 vit D concentrations (66+/-30 vs 145+/-60 nmol/L) whereas in the AVD chicks, boron decreased those concentrations (201+/-74 vs 126+/-32 nmol/L). Regardless of vitamin D nutriture, boron decreased peak pancreatic insulin secretion (9.75 vs 2.77 ng/g dry pancreas/60 s). The findings suggest that boron nutriture is involved in the regulation of two co-dependent metabolites which in turn regulate energy substrate utilization and mineral metabolism. It is reasonable to conclude that boron limits pancreatic beta-cell deterioration that occurs during excessive insulin demand.