Submitted to: Recommended Dietary Allowances Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/1995
Publication Date: N/A
Technical Abstract: Accumulating evidence suggests that boron influences the metabolism of vitamin D. Several indices related to energy substrate utilization and mineral metabolism, all regulated by vitamin D metabolites, respond to dietary boron, especially during concomitant vitamin D deficiency. To characterize further the relation between boron and vitamin D, a study was conducted to determine the effect of boron on circulating 25- hydroxyvitamin D and selected energy substrates. Day-old male broiler chicks were fed low boron diets (<0.17 mg/kg) supplemented with boron (0 or 3 mg/kg) and vit D (0, 125 [Expt 1] or 200 [Expt 2], or 625 ICU/kg) for 27 (Expt 1) or 26 d (Expt 2). In vitamin D-marginal (125 ICU/kg) but not vitamin D deprived (0 ICU/kg) chicks, boron increased serum 25- hydroxyvitamin D3 (measured in Expt 1 only) to detectable concentrations. In Expt 1, vitamin D-marginal, but not vitamin D-deprived or vitamin D- adequate (625 ICU/kg) chicks responded to boron as indicated by improvements in growth, feed efficiency, gross leg structure, and serum concentrations of ionized calcium and triglycerides. In Expt 2 in which a higher intermediate, that is, less marginal, concentration of vitamin D was fed, the response to boron was muted. The findings indicate that dietary boron enhances the efficacy of vitamin D but does not substitute for the vitamin. Further investigation is needed to determine whether boron improves vitamin D absorption or conversion to various active metabolites.