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

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.

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.

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

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.

Effects of boron supplementation on bone mineral density and dietary, blood, and urinary calcium, phosphorus, magnesium, and boron in female athletes.

The effects of boron supplementation on blood and urinary minerals were studied in female college students--17 athletes and 11 sedentary controls--over a one-year period. The athletes had lower percent body fat and higher aerobic capacities than sedentary controls. Athletic subjects consumed more boron in their normal diets than sedentary subjects; all other dietary measures were similar between the two groups. The athletes showed a slight increase in bone mineral density, whereas the sedentary group showed a slight decrease. Serum phosphorus concentrations were lower in boron-supplemented subjects than in subjects receiving placebos, and were lower at the end of the study period than during baseline analysis. Activity depressed changes in serum phosphorus in boron-supplemented subjects. Serum magnesium concentrations were greatest in the sedentary controls whose diets were supplemented with boron, and increased with time in all subjects. A group x supplement interaction was observed with serum magnesium; exercise in boron-supplemented subjects lowered serum magnesium. In all subjects, calcium excretion increased over time; in boron-supplemented subjects, boron excretion increased over time. In all subjects, boron supplementation affected serum phosphorus and magnesium, and the excretion of urinary boron.

The relationship between boron and magnesium status and bone mineral density in the human: a review.

Osteoporosis is a disease that characteristically afflicts postmenopausal women. It is estimated that millions of people are plagued yearly with this debilitating disease. Associated health care costs are in the billions of dollars, annually. Much research has been conducted in the area of osteoporosis and mineral supplementation, mainly focusing on calcium and vitamin D. Nonetheless, more recent studies have reported possible improvements in bone mineral density in women who were supplemented with the ultratrace mineral, boron. Boron may play a role in bone metabolism, but its role is most likely to be associated with its interactions with other minerals and vitamins such as calcium, magnesium and vitamin D. Although the focus of this review will be to discuss the interactive role of boron with magnesium and bone metabolism, some discussion of its interactive role with vitamin D is also necessary.

Diet, hormonal, and metabolic factors affecting bone mineral density in adolescent amenorrheic and eumenorrheic female runners.

Seven adolescent female runners with secondary amenorrhea and six adolescent eumenorrheic female runners received dietary supplements of 1200 mg calcium carbonate and 400 IU vitamin D/d for 12 months. Bone mineral density (BMD) of the axial skeleton was measured by dual photon densitometry at the beginning and end of the 12 month period. Plasma estradiol and ionized calcium concentration were also determined. Bone mineral density decreased in two of the amenorrheic subjects, with the lowest estradiol values concurrent with the severest training regimen and highest calcium intake. There was a significant decrease in plasma estradiol concentration in the amenorrheic runners (p less than 0.05). Plasma ionized calcium and estradiol explained 99% of the variation in BMD (r2 = 0.999). A significant inverse relationship between plasma estradiol and miles run/week was observed (r2 = -0.748). Adolescent female runners who train extensively and have low plasma estradiol levels may be adversely affecting BMD despite supplemental calcium and vitamin D intake.

Mineral retention in young men consuming soy-fiber-augmented liquid-formula diets.

The effect of a nutritionally complete liquid-formula diet without soy polysaccharide or with the fiber source at 20, 30, or 40 g/d on mineral retention in young men was examined. Addition of 20 g soy polysaccharide to the liquid formula significantly (p less than 0.05) improved the retentions of copper, iron, zinc, and magnesium over the diet without added fiber. The highest level of soy polysaccharide (40 g/d) resulted in significantly (p less than 0.05) lower Cu, Zn, Fe, and Mg retentions than did the 20-g diet and the 30-g diet had an intermediate effect. Except for slightly negative Cu (-0.1 +/- 0.4 mg) and Fe (-0.6 +/- 3.7 mg) retentions on the 40-g diet, retentions of all minerals remained positive throughout this study. The liquid-formula diet supplemented with 40 g soy polysaccharide could have a deleterious effect on mineral retentions in persons consuming the diet as their sole nutritional source.

Effect of dietary fat and cholesterol on plasma lipids and lipoprotein fractions in normolipidemic men.

In a controlled feeding situation, male subjects were assigned to one of four treatment groups: low fat (31% of total kcal)/low cholesterol (193 mg/d) (LFLC), low fat/usual cholesterol (504 mg/d) (LFUC), usual fat (46% of total kcal)/low cholesterol (UFLC) and usual fat/usual cholesterol (UFUC) intake. For the first 2 wk of the 10-wk study all subjects consumed the UFUC diet. Subjects consumed experimental diets during wk 3-7 and resumed their customary intake during wk 8-10. Plasma total, high-density-lipoprotein (HDL), low-density-lipoprotein and very-low-density-lipoprotein cholesterol and triglycerides were determined weekly. A significant effect (P less than 0.05) of dietary fat on plasma total and HDL cholesterol was observed between the end of wk 2 and 7. Low fat intake resulted in 17 +/- 2 mg/dL lower total cholesterol and 10 +/- 1 mg/dL lower HDL cholesterol than the usual fat intake. Plasma lipids were not affected either by dietary cholesterol or by any interaction of dietary fat with cholesterol.

Zinc and copper retention during pregnancy: the adequacy of prenatal diets with and without dietary supplementation.

Twenty-four pregnant women, in their second trimester, participated in two seven-day metabolic experiments to evaluate zinc and copper utilization from self-selected diets, with or without supplementation. Recommended dietary allowances for zinc or suggested intakes for copper were not met unless supplements of these nutrients were consumed. Zinc retentions in the unsupplemented group were 1.9 and 0.3 mg/day during the first and second metabolic periods, respectively. Zinc retentions in the supplemented group were 2.3 and 4.7 mg/day during the same two periods. Intakes above 8 mg/day resulted in positive retentions. Based on individual variation, however, intakes of 20 mg/day, the current RDA, would not be excessive although possibly some level between these two extremes would be adequate. Copper retentions in the unsupplemented and supplemented groups combined over the two balance periods were -0.02 and 0.89 mg/day, respectively. Adequate copper retention does not appear possible without the use of a supplement.

Yields and nutrient content of selected fresh fruits.

Proximate composition, edible yields, and selected nutrients were measured in cantaloupe, cherries, grapes, nectarines, plums, and watermelon sampled in six major U.S. markets. Yields were lowest (about 55%) for the melons, but were much higher (about 90% or above) for other fruits. Fruits were high in moisture, low in protein, fat, and energy. The estimated carbohydrate content ranged from about 8% for the melons to 17% for cherries. Vitamins A and C were present in moderate concentrations, but fruits were found to be low in vitamin B-6, folic acid, and pantothenic acid, as well as in the mineral elements.

Effect of caloric restriction during pregnancy on maternal and fetal body composition in the obese Sprague-Dawley rat.

The effects of 15, 30 or 50% caloric restriction during pregnancy on maternal and fetal compartments was determined in obese Sprague-Dawley rats. Pregnant and nonpregnant animals were assigned on a weight basis to one of the dietary treatments. All nutrients, except calories, were fed at levels to meet dietary requirements. Animals were killed on day 20 of treatment and fetuses were taken by Caesarian section. Pregnant animals achieved positive weight gain during 20 days of gestation at all levels of caloric restriction. Nonpregnant animals lost body weight when calories were restricted by 30 and 50%. Number of fetuses, fetal body nitrogen, and pup weight were not statistically different (P less than 0.05) among groups. Animals fed the 30 and 50% calorie-restricted diets showed a significant (P less than 0.05) decrease in total-body fat. Percent carcass protein tended to increase as dietary caloric restriction increased. The fetal compartment was apparently not affected by maternal caloric restriction up to 50% during pregnancy provided that all other nutrients were supplied in adequate amounts. Maternal stores were adversely affected at levels of 30 and 50% caloric restriction.

Effect of dietary zinc and protein levels on the utilization of zinc and copper by adult females.

Zinc and copper utilization were examined in twenty-three young adult females fed either a moderate protein, low zinc diet, a high protein, low zinc diet, a moderate protein, high zinc diet, or a high protein, high zinc diet during a 24-day metabolic balance study. The moderate and high protein diets contained 7.9 g and 15.2 g nitrogen per day, respectively. The low and high levels of zinc were 9.5 or 10.1 and 18.4 or 19.9 mg daily. Copper intake was constant at approximately 2.0 mg/day. Urinary zinc excretion was significantly greater (P less than 0.05) in subjects consuming the high protein diets. Fecal zinc paralleled zinc intake but was not affected by protein intake. Apparent retention of zinc was not significantly different among dietary treatments ranging from -0.29 to 1.58 mg/day. Fecal excretion and apparent retention of copper were not affected by protein intake. Mean copper retentions ranged from 0.12 to 0.30 mg/day. Dietary zinc did not affect copper excretion or retention. Dietary protein, at levels commonly consumed by a substantial portion of the American adult female population, did not affect zinc and copper utilization. Individuals were not consistently in positive balance although average retentions were generally positive.

Feeding behaviors, food attitudes, and body fatness in infants.

One hundred and thirty-four infants were studied at 3 and 9 months of age to determine possible behavioral causes of fatness. A feeding behaviors interview and a semantic differential to measure mothers' attitudes toward food were developed. A stepwise multiple regression procedure revealed that none of the independent variables significantly predicted the dependent variable of infant triceps skinfold thickness at the age of 9 months. Even so, care should be exercised in instructing caregivers concerning specific feeding behaviors to use with infants.

Copper and zinc utilization in elderly adults.

Elderly adults were provided with 2.33 mg of copper and either 7.80 or 23.26 mg of zinc daily during a 30-day metabolic study. Excretions of both minerals were measured throughout the study. The subjects were able to maintain apparent positive balance for copper, but were in negative balance for zinc on both levels off intake. Copper retention was significantly reduced by intake of the higher amount of zinc. These results support other reports indicating antagonism between the two nutrients. The hair content of zinc and copper was higher in females than in males and was in the ranges indicative of long-term adequate intakes. Recumbent length was significantly greater than standing height and should be investigated further as a more accurate measure of body height in the elderly.

Effects of oral contraceptive agents on copper and zinc balance in young women.

Young adult women were selected from a group of volunteers on the basis of present and past use of oral contraceptive agents. Subjects were either those who had never used oral contraceptives or those who had used an agent for a minimum of two menstrual cycles. All subjects were fed diets that provided 2.02 to 2.11 mg of copper and 9.15 to 9.10 mg of zinc daily in an 18-day controlled metabolic study. Both oral contraceptive users and nonusers were in negative zinc balance and zinc excretion as not different (P > 0.05) for the groups. Oral contraceptives did not alter (P > 0.05) the metabolic balance of copper; the mean copper retention values were -0.16 mg/day for the nonusers and -0.13 mg/day for the users of oral contraceptives. As anticipated from reports in the literature, the plasma copper levels were higher (P < 0.01) in the oral contraceptive group, but the levels of zinc were not different. Although blood levels of zinc and copper are usually changed with the use of oral contraceptives, the retention of the two nutrients appears not to be affected.

PIP: Young adult women were selected from a group of volunteers on the basis of present and past use of (OCs) oral contraceptives. Subjects were either those who had never used OCs or those who had used an agent for a minimum of 2 menstrual cycles. All subjects were fed diets which provided 2.02-2.11 mg of copper and 9.15-9.10 mg of zinc daily in an 18-day controlled metabolic study. Both OC users and nonusers were in negative zinc balance and zinc excretion was not different (P 0.05) for the groups. OCs did not alter the metabolic balance of copper (P 0.05); the mean copper retention values were -0.16 mg/day for the nonusers and -0.13 mg/day for OC users. As anticipated from reports in the literature, the plasma copper levels were higher (P 0.01) in the OC group, but the levels of zinc were not different. Although blood levels of zinc and copper are usually changed with the use of OCs, the retention of the 2 nutrients appears not to be affected.

Effects of zinc intake on copper balance in adult females.

Adult women were fed dietary regimens that provided 2.0 mg of copper and either 8, 16, 24, mg of zinc daily in a 18-day controlled metabolic study. Zinc retentions were positive at all levels of intake, but the lowest level was probably not sufficient to maintain equilibrium. An intake of 16 mg of zinc was sufficient to maintain subjects in positive balance or at equilibrium, although this level may be marginal for individuals living in warm climates with potentially large sweat losses. None of the dietary groups was in positive balance on a copper intake of 2 mg/day, although the dietary level of zinc had no effect on copper retentions. Serum levels of copper decreased and zinc increased during the study.