The effect of boron on plasma testosterone and plasma lipids in rats

Recent studies have indicated that dietary boron can affect the concentration of steroid hormones in vivo. It has been suggested that the interaction between boron and steroid hormone metabolism is mediated by the hydroxylation process that steroids need to become biologically active. The increase in the concentration of some steroid hormones may impact favourably on cardiovascular and bone diseases. The following experiment was performed to determine the specificity of the effect of boron on steroid hormones and to determine the subsequent impact on plasma lipids in rats over a 4 week study period. Upon addition of boron (as boric acid) to the drinking water to provide 2 mg boron/rat/day, there was no change in body or testicular weight between the control and treatment groups. The addition of boric acid to the drinking water resulted in significant elevations in the plasma 1,25-dihydroxyvitamin D concentration at week 2 (P<0.01) and the plasma testosterone concentration at week 4 (P<0.05) relative to the control group. After 2 weeks, there was a significant decrease in the plasma triacylglycerol (P<0.05) and total HDL-cholesterol concentrations (P<0.05) in rats fed boric acid relative to their counterparts in the control group. However, at week 4 only HDL(3)-cholesterol was significantly lower (P<0.002). The potentially favourable effects of increasing the concentrations of vitamin D, testosterone and oestrogen (as shown in other studies) on chronic diseases need to be balanced against the reduction in HDL(3)-cholesterol. Copyright (C) 1997 Elsevier Science Inc.