THE EFFECT OF BORON SUPPLEMENTATION ON ITS URINARY-EXCRETION AND SELECTED CARDIOVASCULAR RISK-FACTORS IN HEALTHY MALE-SUBJECTS

Boron (B) is an essential trace element for plants and its interrelati onship with mineral and bone metabolism and endocrine function in huma ns has been proposed. Relatively little is known about the occurrence of B in the food chain and hence a biomarker which reflects its intake is required. Two studies were carried out to quantify the urinary B c oncentration of subjects consuming their habitual diet and the effect of supplementation. Ln addition, the effect of supplementation on plas ma lipoprotein cholesterol concentrations and susceptibility to oxidat ion and plasma steroid hormones were determined. Boron excretion, obta ined on two different occasions from 18 healthy male subjects, was fou nd to be in the range 0.35-3.53 mg/day, with no significant difference between the two occasions. Supplementation with 10 mg B/d for 4 wk re sulted in 84% of the supplemented dose being recovered in the urine. P lasma estradiol concentrations increased significantly as a result of supplementation (51.9 +/- 21.4 to 73.9 +/- 22.2 pmol/L; p < 0.004) and there was a trend for plasma testosterone levels to be increased. How ever, there was no difference in plasma lipids or the oxidizability of low-density lipoprotein. Our studies suggest that the absorption effi ciency of B is very high and estimation of the urinary B concentration may provide a useful reflection of B intake. Ln addition, the elevati on of endogenous estrogen as a result of supplementation suggests a pr otective role for B in atherosclerosis.