Boron Abstracts

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Dietary boron decreases peak pancreatic in situ insulin release in chicks and plasma insulin concentrations in rats regardless of vitamin D or magnesium status

            (Bakken and Hunt 2003) Download

Because dietary boron deprivation induces hyperinsulinemia in vitamin D-deprived rats, the influence of dietary boron on insulin metabolism as modified by nutritional stressors was examined in two animal models. Male weanling Sprague-Dawley rats were assigned to each of four (Experiment 1) or 8 (Experiment 2) dietary groups for 35 d: the basal diet (< 0.2 mg B; <1.0 mg Mg/kg) was supplemented with boron (as orthoboric acid) to contain <0.2 or 2.0 (a physiologic amount) mg B/kg; with magnesium (as magnesium acetate), at 100 (inadequate) or 360-400 (adequate) mg/kg; and with cholecalciferol [vitamin D-3; 25 microg/kg for study length (Experiment 2), or, depleted for 16-17 d then repleted until end of experiment (Experiments 1 and 2)]. In the rat model, boron reduced plasma insulin (Experiment 1, P < 0.002; Experiment 2, P < 0.03), but did not change glucose concentrations regardless of vitamin D-3 or magnesium status. Cockerels (1 d old) were fed a ground corn, high protein casein and corn oil-based basal diet (low boron; 0.3 mg B/kg) supplemented with boron as orthoboric acid to contain 0.3 or 1.65 mg/kg (a physiologic amount) and vitamin D-3 at 3.13 (inadequate) or 15.60 (adequate) microg/kg. In the chick model, boron decreased (P < 0.045) in situ peak pancreatic insulin release at 26-37 d of age regardless of vitamin D-3 nutriture. These results suggest that physiologic amounts of boron may help reduce the amount of insulin required to maintain plasma glucose.

Borate and molybdate inhibition of catechol estrogen and pyrocatechol methylation by catechol-O-methyltransferase

            (Beattie and Weersink 1992) Download

The possibility that boron and molybdenum anions can influence sex steroid metabolism by forming complexes with catechol estrogens has been studied in vitro. The formation of 2-methoxyestrone (2-OHE1 2-Me) from 2-hydroxyestrone (2-OHE1) by catechol-O-methyltransferase (COMT) was followed by measuring the transfer of the radiolabeled methyl group from S-adenosylmethionine. In the presence of both sodium tetraborate and sodium molybdate using a phosphate buffer medium, the formation of 2-OHE1 2-Me decreased as the anion:2-OHE1 molar ratio was increased. However, the reverse effect was observed when using a tris buffer medium and further investigation showed that phosphate and sulphate also enhanced COMT activity in a tris buffer medium. Boric acid affinity medium, used as a substitute for borate salt, also showed a negative relationship with enzyme activity in a phosphate buffer medium, and inhibition of methylation was more marked than with the free anion. Erythrocytes contain appreciable amounts of COMT, which is mostly responsible for the rapid O-methylation of catechol estrogens in blood. The methylation of a simple catechol compound, 1,2-dihydroxybenzene (pyrocatechol) was therefore studied using rat red blood cell lysates. Methylation was inhibited in a concentration-related manner by borate, as found in the studies of 2-OHE1. It is possible that high dietary intakes of boron or molybdenum could regulate the rate of catabolism, or even the metabolic fate of the major estrogens.

The influence of a low-boron diet and boron supplementation on bone, major mineral and sex steroid metabolism in postmenopausal women

            (Beattie and Peace 1993) Download

An increase in dietary intake of B from 0.25 to 3.25 mg/d has been reported to increase plasma oestradiol and testosterone and decrease urinary Ca excretion in postmenopausal women. Consequently, it is suggested that the higher level of B intake could reduce bone loss associated with the menopause and cessation of ovarian function. The present study was designed to investigate the effect of a B supplement on bone mineral absorption and excretion, plasma sex steroid levels and urinary excretion of pyridinium crosslink markers of bone turnover in healthy postmenopausal volunteers. The women were accommodated in a metabolic unit, given a low-B diet (LBD; 0.33 mg/d) for 3 weeks and were asked to take a B supplement of 3 mg/d in addition to the LBD for a further 3 weeks. Changing B intake from 0.33 to 3.33 mg/d had no effect on minerals, steroids or crosslinks. However, the LBD appeared to induce hyperabsorption of Ca since positive Ca balances were found in combination with elevated urinary Ca excretion. This phenomenon may have inhibited or obscured any effect of B.

The metabolic fate of [3H]estradiol in relation to dietary intake of boron in ovariectomized rats

            (Beattie 1993) Download

It has been reported that boron (B) deprivation reversibly lowers plasma estradiol levels in postmenopausal women. In order to establish whether this reflects disturbances in the estrogen catabolic pathway and in particular in catechol estrogen metabolism, the influence of dietary B on the catabolism of [3H]estradiol-17 beta has been studied in ovariectomized rats. Rats were given diets containing < 0.1 or 40 mg B.kg-1, ovariectomized and then infused with [3H]estradiol-17 beta using osmotic pumps. Analysis of urine samples for conjugated, catechol and non-catechol estrogens did not reveal any effects of B on the recovery or the metabolic fate of tritium from the infused estradiol. These results do not therefore support the proposal that B influences estrogen catabolism by interacting with catechol estrogens.

The physiological effects of dietary boron

            (Devirian and Volpe 2003) Download

Boron may be an essential nutrient for animals and humans. Dietary boron influences the activity of many metabolic enzymes, as well as the metabolism of steroid hormones and several micronutrients, including calcium, magnesium, and vitamin D. Boron supplementation in rats and chicks has been shown to increase bone strength. Boron may also play a role in improving arthritis, plasma lipid profiles, and brain function. Additional research is necessary to further clarify boron's influence in human and animal physiology, as well as determine a dietary requirement for humans.

Boron intake and prostate cancer risk

            (Gonzalez, Peters et al. 2007) Download

INTRODUCTION: Experimental studies suggest that boron may prevent prostate cancer. Only one small epidemiological study has been conducted of boron, which found that those in the highest quartile of boron intake had less than half the risk of prostate cancer versus those in the lowest quartile. METHODS: We evaluated the association between boron intake and prostate cancer within the VITamins And Lifestyle (VITAL) cohort. A total of 35,244 men completed the baseline supplement and food frequency questionnaire (FFQ) in 2000-2002. A boron database was constructed from published sources to estimate boron intake from the FFQ and from multivitamins. A total of 832 men developed prostate cancer from baseline to 31 December 2004. RESULTS: Dietary boron intake and total boron intake from diet plus multivitamins were not associated with prostate cancer risk. The hazard ratio of prostate cancer for those in the highest versus lowest quartile of total boron intake was 1.17 (95% CI 0.85, 1.61). This risk did not vary by prostate cancer stage or Gleason score. Furthermore, none of the foods high in boron content was associated with a decreased risk of prostate cancer. DISCUSSION: This cohort study provides no evidence for a preventive role of boron intake on prostate cancer. Since few studies exist on this topic, future research is needed to better elucidate any role that boron may play in the prevention of prostate cancer.

Metabolic responses of postmenopausal women to supplemental dietary boron and aluminum during usual and low magnesium intake: boron, calcium, and magnesium absorption and retention and blood mineral concentrations

            (Hunt, Herbel et al. 1997) Download

Findings from animal studies indicate that dietary boron affects several aspects of mineral metabolism, especially when animals are subjected to nutritional stressors. Eleven postmenopausal volunteers living on a metabolic ward for 167 d (one 23-d equilibration period and six 24-d treatment periods) were fed a conventional basal diet that supplied a daily average intake of 0.36 mg B, 109 mg Mg, and < 0.10 mg A1/8400 kJ. They were given supplements of 0 (BB) or 3 mg B (SB, last two periods only), 0 (BMg) or 200 mg Mg (SMg) (with magnesium supplements held constant during the last two periods), or 0 (BAl) or 1000 mg A1 (SAl)/d. The SB treatment, compared with the BB treatment, provided a 9.0-fold increase in dietary boron but yielded only a 1.5-fold increase in plasma boron concentrations. Regardless of boron dietary treatment, fecal plus urinary excretion of boron accounted for nearly 100% of dietary boron intake with no evidence of boron accumulation over time. Lack of boron accumulation and relatively small changes in blood boron values during a substantial increase in dietary boron support the concept of boron homeostasis. In subjects fed BMg, SB decreased the percentage of dietary calcium lost in the urine but increased that percentage in volunteers fed SMg, a relation that may be important in understanding metabolic mineral disorders that perturb calcium balance. Reduced calcium absorption during SAl suggests that aluminum supplementation should be limited or at least monitored in postmenopausal women prone to excessive calcium loss. Decreased total urinary oxalate during SB in BMg subjects indicates a possible role for boron in the control of urolithiasis during low-magnesium nutriture.

Dietary boron and hormone replacement therapy as risk factors for lung cancer in women

            (Mahabir, Spitz et al. 2008) Download

Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron may have actions similar to those of HRT; however, no previous study has reported the associations between dietary boron intake and lung cancer risk or the joint effects of boron intake and HRT use on lung cancer risk. The authors examined the associations between boron intake and the joint effects of boron intake and HRT on lung cancer risk in women. In an ongoing case-control study in Houston, Texas (July 1995 through April 2005, end date for this analysis), 763 women were diagnosed with lung cancer, and 838 were matched healthy controls with data on both diet and HRT. Multiple logistic regression analyses were conducted to assess the associations between dietary boron and HRT with lung cancer risk. After adjustment for potential confounders, the odds ratios for lung cancer with decreasing quartiles of dietary boron intake were 1.0, 1.39 (95% confidence interval (CI): 1.02, 1.90), 1.64 (95% CI: 1.20, 2.24), and 1.95 (95% CI: 1.42, 2.68) mg/day, respectively, for all women (p(trend) < 0.0001). In joint-effects analyses, compared with women with high dietary boron intake who used HRT, the odds ratio for lung cancer for low dietary boron intake and no HRT use was 2.07 (95% CI: 1.53, 2.81). Boron intake was inversely associated with lung cancer in women, whereas women who consumed low boron and did not use HRT were at substantial increased odds.

Effect of boron supplementation on blood and urinary calcium, magnesium, and phosphorus, and urinary boron in athletic and sedentary women

            (Meacham, Taper et al. 1995) Download

It has been reported that boron may be beneficial for optimal calcium metabolism and, thus, optimal bone metabolism. Therefore, we designed a study to determine the effects of boron supplementation on blood and urinary minerals in athletic subjects and sedentary control subjects consuming self-selected typical Western diets. Serum phosphorus concentrations were lower in boron-supplemented subjects than in placebo-supplemented subjects. Compared with all other subjects, serum magnesium concentrations were greatest in the sedentary control subjects supplemented with boron and increased with time in all subjects. Exercise training diminished changes in serum phosphorus concentrations caused by boron supplementation. Calcium excretion increased over time in all groups combined, and boron excretion increased over time in all boron-supplemented subjects. The findings suggest that boron supplementation modestly affected mineral status, and exercise modified the effects of boron supplementation on serum minerals.

Up-regulatory impact of boron on vitamin D function -- does it reflect inhibition of 24-hydroxylase?

            (Miljkovic, Miljkovic et al. 2004) Download

Nutritional intakes of boron have been shown to lessen the adverse consequences of vitamin D deficiency in rodents. Pilot clinical studies suggest that this effect may be mediated, in whole or in part, by an increase in serum 25-hydroxyvitamin D. We propose that, in concentrations achievable with good diets, boron suppresses the activity of the microsomal enzyme 24-hydroxylase, chiefly responsible for catabolism of this steroid. This inhibition may reflect a direct interaction with the enzyme, or perhaps boron's ability to form a covalent complex with the product of its activity, 24,25-dihydroxyvitamin D. An up-regulatory impact of boron on 25-hydroxyvitamin D is potentially beneficial in light of the fact that the vitamin D status of many individuals is poor during winter months, and traditional supplemental doses of this vitamin are often too low to correct this problem. There is growing evidence that good vitamin D status -- as reflected by 25-hydroxyvitamin D levels -- may reduce risk for a host of prominent disorders; thus, boron may have the ability to potentiate this protection. Clinical studies also suggest that nutritional boron can up-regulate 17beta-estradiol levels in women, including postmenopausal women receiving hormone replacement therapy. The catabolism of this hormone is achieved by microsomal enzymes catalyzing vicinal hydroxylations -- a description that also applies to 24-hydroxylase. This suggests the more general hypothesis that nutritional boron can inhibit a range of microsomal enzymes which insert hydroxyl groups vicinal to existing hydroxyls in steroids -- including the enzymes which catabolize estradiol and 25-hydroxyvitamin D.

The effect of boron supplementation on its urinary excretion and selected cardiovascular risk factors in healthy male subjects

            (Naghii and Samman 1997) Download

Boron (B) is an essential trace element for plants and its interrelationship with mineral and bone metabolism and endocrine function in humans 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 concentration of subjects consuming their habitual diet and the effect of supplementation. In addition, the effect of supplementation on plasma lipoprotein cholesterol concentrations and susceptibility to oxidation and plasma steroid hormones were determined. Boron excretion, obtained on two different occasions from 18 healthy male subjects, was found 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 resulted in 84% of the supplemented dose being recovered in the urine. Plasma 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. However, there was no difference in plasma lipids or the oxidizability of low-density lipoprotein. Our studies suggest that the absorption efficiency of B is very high and estimation of the urinary B concentration may provide a useful reflection of B intake. In addition, the elevation of endogenous estrogen as a result of supplementation suggests a protective role for B in atherosclerosis.

Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women

            (Nielsen, Hunt et al. 1987) Download

A study was done to examine the effects of aluminum, magnesium, and boron on major mineral metabolism in postmenopausal women. This communication describes some of the effects of dietary boron on 12 women between the ages of 48 and 82 housed in a metabolic unit. A boron supplement of 3 mg/day markedly affected several indices of mineral metabolism of seven women consuming a low-magnesium diet and five women consuming a diet adequate in magnesium; the women had consumed a conventional diet supplying about 0.25 mg boron/day for 119 days. Boron supplementation markedly reduced the urinary excretion of calcium and magnesium; the depression seemed more marked when dietary magnesium was low. Boron supplementation depressed the urinary excretion of phosphorus by the low-magnesium, but not by the adequate-magnesium, women. Boron supplementation markedly elevated the serum concentrations of 17 beta-estradiol and testosterone; the elevation seemed more marked when dietary magnesium was low. Neither high dietary aluminum (1000 mg/day) nor an interaction between boron and aluminum affected the variables presented. The findings suggest that supplementation of a low-boron diet with an amount of boron commonly found in diets high in fruits and vegetables induces changes in postmenopausal women consistent with the prevention of calcium loss and bone demineralization.

Nutritional requirements for boron, silicon, vanadium, nickel, and arsenic: current knowledge and speculation

            (Nielsen 1991) Download

Definition of specific biochemical functions in higher animals (including humans) for the ultratrace elements boron, silicon, vanadium, nickel, and arsenic still has not been achieved although all of these elements have been described as being essential nutrients. Recently, many new findings from studies using molecular biology techniques, sophisticated equipment, unusual organisms, and newly defined enzymes have revealed possible sites of essential action for these five elements. Based on these findings and the response of animals and/or humans to low intakes of these elements, the following speculations have been presented: 1) Boron has a role that affects cell membrane characteristics and transmembrane signaling. 2) Silicon is necessary for the association between cells and one or more macromolecules such as osteonectin, which affects cartilage composition and ultimately cartilage calcification. 3) Vanadium reacts with hydrogen peroxide to form a pervanadate that is required to catalyze the oxidation of halide ions and/or stimulate the phosphorylation of receptor proteins. 4) Nickel is needed for the CO2-fixation to propionyl-CoA to form D-methylmalonyl-CoA. 5) Arsenic has an important role in the conversion of methionine to its metabolites taurine, labile methyl, and the polyamines. If any of these speculations are found to be true, the element involved will be firmly established as having a nutritional requirement because the body obviously cannot synthesize it. Based on animal findings, the dietary requirement is likely to be small; that is, expressed in micrograms per day.

Biochemical and physiologic consequences of boron deprivation in humans

            (Nielsen 1994) Download

Boron deprivation experiments with humans have yielded some persuasive findings for the hypothesis that boron is an essential nutrient. In the first nutritional study with humans involving boron, 12 postmenopausal women first were fed a diet that provided 0.25 mg boron/2000 kcal for 119 days, and then were fed the same diet with a boron supplement of 3 mg boron/day for 48 days. The boron supplementation reduced the total plasma concentration of calcium and the urinary excretions of calcium and magnesium, and elevated the serum concentrations of 17 beta-estradiol and testosterone. This study was followed by one in which five men over the age of 45, four postmenopausal women, and five postmenopausal women on estrogen therapy were fed a boron-low diet (0.23 mg/2000 kcal) for 63 days, then fed the same diet supplemented with 3 mg boron/day for 49 days. The diet was low in magnesium (115 mg/2000 kcal) and marginally adequate in copper (1.6 mg/2000 kcal) throughout the study. This experiment found higher erythrocyte superoxide dismutase, serum enzymatic ceruloplasmin, and plasma copper during boron repletion than boron depletion. The design of the most recent experiment was the same as the second study, except this time the diet was adequate in magnesium and copper. Estrogen therapy increased plasma copper and serum 17 beta-estradiol concentrations; the increases were depressed by boron deprivation. Estrogen ingestion also increased serum immunoreactive ceruloplasmin and erythrocyte superoxide dismutase; these variables also were higher during boron repletion than depletion for all subjects, not just those ingesting estrogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Is boron nutritionally relevant?

            (Nielsen 2008) Download

Evidence from numerous laboratories using a variety of experimental models, including humans, shows that boron is a bioactive beneficial element. Much evidence has come from studies that did not require nutritional or environmental stressors or fastidious methods in diet preparation or environmental control. The evidence includes deprivation studies showing that boron is necessary for some higher animals to complete the life cycle, and that realistic low boron intakes result in impaired bone health, brain function, and immune response. Thus, low boron intake is a relevant nutritional concern, which diets rich in fruits, vegetables, nuts, and pulses can prevent.

Dietary boron, brain function, and cognitive performance

            (Penland 1994) Download

Although the trace element boron has yet to be recognized as an essential nutrient for humans, recent data from animal and human studies suggest that boron may be important for mineral metabolism and membrane function. To investigate further the functional role of boron, brain electrophysiology and cognitive performance were assessed in response to dietary manipulation of boron (approximately 0.25 versus approximately 3.25 mg boron/2000 kcal/day) in three studies with healthy older men and women. Within-subject designs were used to assess functional responses in all studies. Spectral analysis of electroencephalographic data showed effects of dietary boron in two of the three studies. When the low boron intake was compared to the high intake, there was a significant (p < 0.05) increase in the proportion of low-frequency activity, and a decrease in the proportion of higher-frequency activity, an effect often observed in response to general malnutrition and heavy metal toxicity. Performance (e.g., response time) on various cognitive and psychomotor tasks also showed an effect of dietary boron. When contrasted with the high boron intake, low dietary boron resulted in significantly poorer performance (p < 0.05) on tasks emphasizing manual dexterity (studies II and III); eye-hand coordination (study II); attention (all studies); perception (study III); encoding and short-term memory (all studies); and long-term memory (study I). Collectively, the data from these three studies indicate that boron may play a role in human brain function and cognitive performance, and provide additional evidence that boron is an essential nutrient for humans.

The nutritional and metabolic effects of boron in humans and animals

            (Samman, Naghii et al. 1998) Download

We have undertaken studies in humans and animals that aimed to obtain further information about the intake and excretion of boron (B) as well as its effects on markers of coronary heart disease. In humans, we have shown that the intake of B is 2.2 mg/d; its urinary excretion is 1.9 mg/d, and there appears to be little intraindividual variation. Supplementation with 10 mg of B/d resulted in the recovery of 84% of the dose in the urine and a significant increase in plasma estradiol concentration, but no effect on plasma lipoproteins. In rats, increasing the intake of B through the drinking water is reflected in the tissue concentrations, results in an increase in plasma testosterone and vitamin D, and results in a decrease in HDL cholesterol. It is clear that B has the potential to impact significantly on a number of metabolic processes.

Comparative effects of boric acid and calcium fructoborate on breast cancer cells

            (Scorei, Ciubar et al. 2008) Download

Recent studies suggested that boron has a chemo-preventive role in prostate cancer. In the present report, we investigated the effects of calcium fructoborate (CF) and boric acid (BA) on activation of the apoptotic pathway in MDA-MB-231 human breast cancer cells. Exposure to BA and CF inhibited the proliferation of breast cancer cells in a dose-dependent manner. Treatment with CF but not BA resulted in a decrease in p53 and bcl-2 protein levels. Furthermore, after the treatment with CF, augmentation of pro-caspase-3 protein expression, cytosolic cytochrome c level, and caspase-3 activity were observed, indicating apoptotic cell death induction. This was also demonstrated by terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end-labeling assay. In conclusion, our data provide arguments to the fact that both BA and CF inhibited the growth of breast cancer cells, while only CF induced apoptosis. Additional studies will be needed to identify the underlying mechanism responsible for the observed cellular responses to these compounds and to determine if BA and CF may be further evaluated as chemotherapeutic agents for human cancer.

Dietary boron supplementation enhanced the action of estrogen, but not that of parathyroid hormone, to improve trabecular bone quality in ovariectomized rats

            (Sheng, Taper et al. 2001) Download

This study investigated whether boron would enhance the ability of 17beta-estradiol (E2) or parathyroid hormone (PTH) to improve bone quality in ovariectomized OVX rats. Adult OVX rats were treated for 5 wk with vehicle, boron (5 ppm as boric acid), E2 (30 microg/kg/d, sc), PTH (60 microg/kg/d, sc), or a combination of boron and E2 or PTH, respectively. The E2 treatment corrected many adverse effects of OVX on bone quality, increased bone Ca, P, and Mg contents, and decreased trabecular plate separation. Dietary boron supplementation had no effects on these bone parameters in OVX rats. When OVX rats were treated with boron and E2 together, trabecular bone volume (Tb.BS/TV) and plate density were increased significantly more than that caused by E2 alone. The boron and E2 combination also increased trabecular bone surface (Tb.BV/TV) and decreased trabecular plate separation in OVX rats. In contrast, whereas daily PTH injection also increased bone Ca, Mg, and P contents, Tb.BV/TV, Tb.BS/TV, trabecular plate density and thickness, and decreased trabecular plate separation in OVX rats, the combination of boron and PTH had no additional improvement in bone quality over that achieved by PTH alone. In summary, this study shows for the first time that boron enhanced the action of E2, but not that of PTH, to improve trabecular bone quality in OVX rats.

Dietary boron supplementation enhances the effects of estrogen on bone mineral balance in ovariectomized rats

            (Sheng, Taper et al. 2001) Download

The present study investigated whether boron would enhance the action of 17beta-estradiol (E2) or parathyroid hormone (PTH) on bone mineral balance in ovariectomized (OVX) rats. Forty-three days after OVX, the rats were treated for 5 wk with vehicle, boron (5 ppm as boric acid), E2 (30 microg/kg/d, sc), PTH (60 microg/kg/d, sc), or a combination of boron and E2 or PTH. Bone mineral balance was assessed by measuring apparent absorption, excretion, and retention of calcium (Ca), phosphorus (P), and magnesium (Mg). Serum Ca, P, Mg, and osteocalcin were also measured in this experiment. Boron alone had no effects on food consumption, weight gain, bone mineral balance, and serum levels of Ca, P, Mg, and osteocalcin. E2 alone increased serum P and Mg and decreased serum osteocalcin, but it had no effect on bone mineral balance. The combination of boron and E2 markedly improved apparent absorption of Ca, P, and Mg. In addition, the combination treatment increased the apparent retention of Ca and Mg (but not P) and also increased serum Ca and Mg but not serum P. On the other hand, boron cotreatment did not prevent the E2-induced reduction in serum osteocalcin in OVX rats. PTH alone significantly increased serum Ca, P, Mg, and osteocalcin concentrations, although it had no effect on bone mineral balance. Contrary to the boron-E2 combination treatment, the combination of boron and PTH did not enhance bone mineral balance. However, inasmuch as boron-PTH cotreatment did not enhance the stimulatory action of PTH on serum Ca, P, and osteocalcin, boron completely abolished the stimulatory effect of PTH on serum Mg. In conclusion, we have demonstrated for the first time that although boron by itself has no effect on bone mineral homeostasis, it appears to have synergistic enhancing effects on the action of E2 on Ca and Mg homeostasis in OVX rats.


References

Bakken, N. A. and C. D. Hunt (2003). "Dietary boron decreases peak pancreatic in situ insulin release in chicks and plasma insulin concentrations in rats regardless of vitamin D or magnesium status." J Nutr 133(11): 3577-83.

Beattie, J. H. (1993). "The metabolic fate of [3H]estradiol in relation to dietary intake of boron in ovariectomized rats." J Steroid Biochem Mol Biol 45(6): 549-54.

Beattie, J. H. and H. S. Peace (1993). "The influence of a low-boron diet and boron supplementation on bone, major mineral and sex steroid metabolism in postmenopausal women." Br J Nutr 69(3): 871-84.

Beattie, J. H. and E. Weersink (1992). "Borate and molybdate inhibition of catechol estrogen and pyrocatechol methylation by catechol-O-methyltransferase." J Inorg Biochem 46(3): 153-60.

Devirian, T. A. and S. L. Volpe (2003). "The physiological effects of dietary boron." Crit Rev Food Sci Nutr 43(2): 219-31.

Gonzalez, A., U. Peters, et al. (2007). "Boron intake and prostate cancer risk." Cancer Causes Control 18(10): 1131-40.

Hunt, C. D., J. L. Herbel, et al. (1997). "Metabolic responses of postmenopausal women to supplemental dietary boron and aluminum during usual and low magnesium intake: boron, calcium, and magnesium absorption and retention and blood mineral concentrations." Am J Clin Nutr 65(3): 803-13.

Mahabir, S., M. R. Spitz, et al. (2008). "Dietary boron and hormone replacement therapy as risk factors for lung cancer in women." Am J Epidemiol 167(9): 1070-80.

Meacham, S. L., L. J. Taper, et al. (1995). "Effect of boron supplementation on blood and urinary calcium, magnesium, and phosphorus, and urinary boron in athletic and sedentary women." Am J Clin Nutr 61(2): 341-5.

Miljkovic, D., N. Miljkovic, et al. (2004). "Up-regulatory impact of boron on vitamin D function -- does it reflect inhibition of 24-hydroxylase?" Med Hypotheses 63(6): 1054-6.

Naghii, M. R. and S. Samman (1997). "The effect of boron supplementation on its urinary excretion and selected cardiovascular risk factors in healthy male subjects." Biol Trace Elem Res 56(3): 273-86.

Nielsen, F. H. (1991). "Nutritional requirements for boron, silicon, vanadium, nickel, and arsenic: current knowledge and speculation." FASEB J 5(12): 2661-7.

Nielsen, F. H. (1994). "Biochemical and physiologic consequences of boron deprivation in humans." Environ Health Perspect 102 Suppl 7: 59-63.

Nielsen, F. H. (2008). "Is boron nutritionally relevant?" Nutr Rev 66(4): 183-91.

Nielsen, F. H., C. D. Hunt, et al. (1987). "Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women." FASEB J 1(5): 394-7.

Penland, J. G. (1994). "Dietary boron, brain function, and cognitive performance." Environ Health Perspect 102 Suppl 7: 65-72.

Samman, S., M. R. Naghii, et al. (1998). "The nutritional and metabolic effects of boron in humans and animals." Biol Trace Elem Res 66(1-3): 227-35.

Scorei, R., R. Ciubar, et al. (2008). "Comparative effects of boric acid and calcium fructoborate on breast cancer cells." Biol Trace Elem Res 122(3): 197-205.

Sheng, M. H., L. J. Taper, et al. (2001). "Dietary boron supplementation enhanced the action of estrogen, but not that of parathyroid hormone, to improve trabecular bone quality in ovariectomized rats." Biol Trace Elem Res 82(1-3): 109-23.

Sheng, M. H., L. J. Taper, et al. (2001). "Dietary boron supplementation enhances the effects of estrogen on bone mineral balance in ovariectomized rats." Biol Trace Elem Res 81(1): 29-45.