Calcium supplementation and bone loss in middle-aged women

Heated oyster shell-seaweed calcium (AAA Ca) on osteoporosis

A randomized, prospective, double-blind test was carried out to compare the effects of heated oyster shell-seaweed calcium (AAA Ca), calcium carbonate, and placebo in 58 elderly, hospitalized women with the mean age of 80 divided into three groups. Group A received 900 mg/day Ca as AAA Ca, Group B 900 mg/day Ca as CaCO3, and Group C placebo besides regular hospital diet containing approximately 600 mg Ca/day for 24 months. From the 25th to the 30th month, all groups were given AAA Ca. Lumbar spine and radial bone mineral density (BMD) were measured at 3-month intervals. Urinary Ca/Cr and serum alkaline phosphatase, intact and midportion serum parathyroid hormone (PTH), and calcitonin were also measured at intervals. From the 6th to the 24th month of the study, the ratio of lumbar spine BMD (L2-L4 by DPX, Lunar) to the basal pretest value was consistently and significantly higher in Group A than Group C but not higher in Group B than in Group C. PTH, measured 12 months after the beginning of the study, was lower in Group A than in Group C, but no significant difference was found between Groups B and C. At 3 months after the placebo was switched to AAA Ca in Group C, serum PTH was significantly decreased from the level during placebo supplement. Morning urine Ca/Cr decreased in Groups A after 18 months and in B after 12 months, but not in C. Serum alkaline phosphatase decreased in Group A significantly compared with Group C, but not in Group B. AAA Ca appears to be effective for increasing BMD in elderly subjects.

Physical activity, nutrition, and chronic disease

Epidemiologic, animal, clinical, and metabolic studies demonstrate the independent roles of physical activity and nutrition in the prevention and treatment of several chronic diseases. Fewer data are available to describe the synergistic effects of exercise and diet, and questions remain as to whether and how these two lifestyle factors work together to promote health and prevent disease. This paper briefly reviews many of the known effects of physical activity and nutrition on the prevention and treatment of coronary heart disease, non-insulin-dependent diabetes mellitus, obesity, and osteoporosis as well as how exercise and diet may work together. A discussion of how to increase physical activity levels and how to improve dietary intake also is included. Finally, current exercise and dietary recommendations are summarized, as are directions for future research.

Factors influencing dairy calcium intake in women

OBJECTIVES

Most national dietary studies have reported inadequate calcium (Ca) intake by women, indicating that marketing and educational efforts have not effected dietary behavior changes. The purpose of this study was to identify knowledge, attitudes, and behaviors which influence dairy Ca intake.

METHODS

A questionnaire was developed to accomplish these objectives, and piloted for clarity and content validity. Dietary Ca intake was assessed using a food frequency questionnaire. After revisions, women were sampled from four sources: a health spa, elderhostel classes, through a Cooperative Extension Service program, and from the Illinois Older Women's League. The response rate was 66.5%.

RESULTS

Mean total reported Ca intake (n = 351) was 591 +/- 355 mg/day. Over 40% of the women reported Ca intakes below 60% of the RDA and could therefore be considered to have deficient intake. Unfortunately, 27.1% of these with deficient intake believed they were meeting the Ca RDA. Significant differences (p < or = 0.01) were found in attitudes and beliefs about dairy Ca when comparing women whose intake was below 60% of the RDA with those whose intake was above 60%. The most commonly mentioned beliefs of the entire sample concerned cholesterol (16.5%), high calories (13.7%) and gastrointestinal discomfort (12.8%).

CONCLUSIONS

These findings suggest an important discrepancy between perceived and actual Ca intake which could influence receptiveness to education. Non-dairy Ca rich food sources need to be clarified as does the caloric and cholesterol content of dairy foods.

The effects of calcium supplementation (milk powder or tablets) and exercise on bone density in postmenopausal women

The etiology of age-related bone loss is unclear but both lack of exercise and dietary calcium deficiency have been implicated in its causation. This 2-year randomized placebo-controlled study was designed to examine the effects of increased dietary calcium and exercise in 168 women who were more than 10 years postmenopausal. The subjects were randomized into one of 4 groups: placebo, milk powder containing 1 g of calcium, calcium tablets 1 g/night, and calcium tablets 1 g/night and an exercise regimen. The exercise group aimed to undertake 4 h of extra weight-bearing exercise per week and were undertaking 10% more activity than other groups at 2 years. Bone mineral density at the lumbar spine, three hip sites, and two sites of the tibia close to the ankle joint were measured at 6 month intervals. Dietary intake was evaluated by a weighed food record, exercise was evaluated by an exercise diary, and blood and urine samples were obtained to examine effects on calcium homeostasis. Individual data points were compared using repeated measures ANOVA and least squares regression. Calcium supplementation by either the calcium tablets or the milk powder resulted in cessation of bone loss at the intertrochanteric hip site (placebo, calcium tablets, calcium and exercise, milk powder -0.81, +0.17, +0.23, and +0.07% per year, respectively; p < 0.05 for all supplementation groups compared with placebo) with similar results at the trochanteric hip site. The calcium and exercise group had less bone loss at the femoral neck site when compared with calcium supplementation alone (placebo, calcium tablets, calcium and exercise, milk powder -0.67, -0.18, +0.28, and -0.18% per year, respectively; p < 0.05 for calcium and exercise compared with calcium alone). There was a significant reduction in the rate of bone loss at the ultradistal site of the tibia (placebo, calcium tablets, calcium and exercise, milk powder -2.5, -1.6, -1.0, and -1.5% per year, respectively; p < 0.05 for all supplementation groups compared with placebo). There was no significant bone loss at the spine site in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term effects of calcium supplementation on bone loss and fractures in postmenopausal women: a randomized controlled trial

PURPOSE

To determine the long-term effects of calcium supplements or placebo on bone density in healthy women at least 3 years postmenopause.

PATIENTS AND METHODS

Eighty-six women from our previously reported 2-year study agreed to continue on their double-blind treatment allocation (1 g elemental calcium or placebo) for a further 2 years, with 78 women (40 on placebo) reaching the 4-year end point. Median (interquartile range) dietary calcium intakes for the whole group were 700 mg (range 540 to 910) per day at baseline, 670 mg (range 480 to 890) per day at 2 years, and 640 mg (range 460 to 880) per day at 4 years. The bone mineral density (BMD) of the total body, lumbar spine, and proximal femur was measured every 6 months by dual-energy, x-ray absorptiometry.

RESULTS

There was a sustained reduction in the rate of loss of total body BMD in the calcium group throughout the 4-year study period (P = 0.002), and bone loss was significantly less in the calcium-treated subjects in years 2 through 4 also (difference between groups 0.25% +/- 0.11% per year, P = 0.02). In the lumbar spine, bone loss was reduced in the calcium group in year 1 (P = 0.004), but not subsequently. There was, however, a significant treatment effect at this site over the whole 4-year period (P = 0.03). In the proximal femur, the benefit from calcium treatment also tended to be greater in the first year and was significant over the 4-year study period in the femoral neck (P = 0.03) and the trochanter (P = 0.01). Nine symptomatic fractures occurred in 7 subjects in the placebo group and 2 fractures in 2 subjects receiving calcium (P = 0.037).

CONCLUSIONS

Calcium supplementation produces a sustained reduction in the rate of loss of total body BMD in healthy postmenopausal women.

Spinal bone mineral loss in estrogen-replete, calcium-replete premenopausal women

After peak bone mass in women is attained, the benefits of increased dietary calcium or supplemental calcium are uncertain. In a longitudinal, 4-year study we have investigated the effect of calcium intake on bone mineral in a group of 41 premenopausal women, aged 38-42 years at entry. Skeletal density was measured four times during the 4-year follow-up; spinal trabecular bone density (STBD) was measured by quantitative computed tomography, and midradius bone mineral density (RBMD) was measured by single photon absorptiometry. At baseline, no differences in bone density were observed among subjects in the highest and lowest quartiles of habitual dietary intake. Overall, STBD declined -0.86 +/- 0.15% per year (p < 0.001), but RBMD did not decline. Total calcium intake (dietary calcium plus supplemental calcium) did not correlate with the rate of STBD loss. Serum estradiol level did not decrease during the study, and bone loss did not correlate with the mean estradiol level. We conclude that premenopausal women in the fifth decade lose about 1% of spinal trabecular mineral yearly, in spite of a normal serum estradiol level and ample calcium intake.

Bone mineralization in children and adolescents with a milk allergy

To evaluate the correlation between dietary calcium intake and mineralization of the immature skeleton 55 children and adolescents aged 5-14 years (mean, 9.5 years) with a positive radioallergosorbent test (RAST) for serum antibodies to cow's milk protein were evaluated. Bone mineral density (BMD) in the lumbar spine and proximal femurs were measured by dual energy X-ray absorptiometry. BMD at each site for each subject was converted to an age-adjusted Z score based on our own series of 95 normal pediatric controls. Calcium intake was determined using a detailed food frequency questionnaire administered by a nutritionist during a 30-40-min interview. Dietary adjustments to the condition varied and resulted in a wide range of calcium intakes. Calcium supplements were taken by 22% of the subjects and were included in the determination of daily calcium intake. The group of 55 subjects was divided into quartiles based on calcium intake (mean +/- S.E mg calcium/day): Group 1, 409 +/- 21, Group 2, 663 +/- 16, Group 3, 950 +/- 32, Group 4, 1437 +/- 124. Bone density Z scores in the proximal femur serially increased across the calcium intake groups (mean +/- S.E.): Group 1, -0.16 +/- 0.31; Group 2, 0.05 +/- 0.33; Group 3, 0.44 +/- 0.24; Group 4, 0.79 +/- 0.41 (P = 0.03). A similar pattern was found with lumbar spine BMD Z scores: Group 1, -0.16 +/- 0.27; Group 2, 0.10 +/- 0.21; Group 3, 0.18 +/- 0.20; Group 4, 0.30 +/- 0.25 (P = 0.05). These data add further to the evidence that dietary calcium intake is important for optimal mineralization of the growing skeleton.

Lifetime milk consumption and bone mineral density in older women

This study examined the relationship between lifetime milk consumption both axial and appendicular bone mineral density in 581 postmenopausal White women. Positive significant, graded associations between milk consumption in adulthood and bone mineral density at the spine, total hip, trochanter, intertrochanter, and midradius, but not the ultradistal wrist or femoral neck, were observed. Adolescent milk consumption showed similar, statistically significant associations (spine and midradius). Associations were independent of age, body mass index, years postmenopausal, thiazide, estrogen and alcohol use, smoking, and exercise. Regular milk consumption in youth and adulthood is associated with better bone mineral density at cortical and trabecular sites in elderly women.

Long-term effect of calcium supplementation on bone loss in perimenopausal women

We observed in a controlled 2 year longitudinal trial in 248 perimenopausal women that a daily calcium supplement of either 1000 or 2000 mg Ca2+ significantly reduced lumbar bone loss and bone turnover in the first year of calcium supplementation. In the second supplementation year the rate of lumbar bone loss in the treated subjects was not significantly different from that in the control group, although two of the three biochemical parameters of bone turnover remained decreased throughout the study. To quantify further the long-term effect of calcium supplementation, we extended the study for another year in 214 women. In the women of the control group who were menstruating until the last year of the trial, the mean change in lumbar bone mineral density after 3 years was -3.2% of the initial value versus 1.6% in the calcium-supplemented groups (p < 0.01). The decrease in lumbar bone loss in these supplemented premenopausal and early perimenopausal women remained statistically significant in the second and third years of supplementation. In the women who stopped menstruating before or during the study, the long-term reduction in lumbar bone loss was not significant (mean difference between control and treatment groups < 0.6% points after 3 years). The decrease in metacarpal cortical thickness (MCT) in the treated subjects during 3 years was on average -3.0% of the initial value in the control versus -2.0% in the supplemented subjects (P < 0.01). The effect of calcium supplementation on MCT was not significantly related to the menopausal status of the subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Chicken soup revisited: calcium content of soup increases with duration of cooking

Because low dietary calcium intake may accelerate bone loss, patients often are advised to increase their dietary intake of calcium. However, some patients may be unable to tolerate good calcium sources such as dairy products. We postulated that the calcium content of soups and stews could be increased by prolonged cooking with a beef bone. Three experiments were done to prove this theory: (1) a bone soup made with a beef bone and distilled water, cooked for 24 hours; (2) a bone-vegetable soup cooked the same way; and (3) a vegetable soup made the same way but without the bone. It was concluded that prolonged cooking of a bone in soup increases the calcium content of the soup when cooked at an acidic, but not at a neutral pH.

Dietary calcium intake relates to bone mineral density in premenopausal women

Bone density and Ca intake were assessed in fifty-six healthy premenopausal women, aged 21-47 years. Bone density was measured at the spine (lumbar vertebrae 1-4, anterio-posterior view), the non-dominant femur (neck, Ward's triangle and trochanter) and radius (33% distal and ultradistal) using dual energy X-ray absorptiometry (Lunar DPX-L). The mean values (SD) for bone density (g/cm2) were 1.18 (0.10) at the lumbar spine, 0.81(0.10) at the trochanter and for Ca intake 783 (329) mg. Bone density values were close to published normal values for young women and the Ca intakes were close to the recommended levels for the UK. However, there was a wide range especially in dietary Ca intake, and 27% of the group were at or below 500 mg/d. Correlations between Ca intake and bone density were highly significant at all three femoral sites (neck r 0.41; Ward's triangle r 0.40, P < 0.01; trochanter r 0.47, P < 0.001), significant at the spine (r 0.27, P < 0.05) but not found at the radius. These correlations were independent of body mass. The low levels of Ca intake found in a substantial proportion of this selected group of young women and their association with low femoral bone density are cause for concern.

Magnitude and determinants of premenopausal bone loss

Bone loss prior to menopause may contribute to a woman's risk for fracture due to osteoporosis later in life. Most, but not all, longitudinal and cross-sectional studies suggest that bone mass decreases prior to menopause. This bone loss may be prevented by calcium supplementation. Heredity, exercise and menstrual status also have an impact on bone mass. Prevention of bone loss prior to menopause will allow women to enter menopause with a greater bone mass reducing their risk of subsequent fracture.

Does diet provide adequate amounts of calcium, iron, magnesium, and zinc in a well-educated adult population?

Standard advice from dietitians, nutritionists, and physicians is that if one eats a well-balanced diet containing a variety of foods, supplements are not necessary. Little information is available, especially in those over 75, to determine whether actual diets do provide adequate amounts of these minerals. The participants of the Baltimore Longitudinal Study of Aging provide seven-day records which include vitamin and mineral supplement intakes. Median daily dietary intakes from diet in all 564 subjects and from diet plus supplements in those who use them were analyzed by age group and gender. More women than men took supplements. Median intakes of calcium from diet were below the recommended dietary allowance (RDA) for unsupplemented women and for supplemented women over 60. Approximately 25% of women under 50 and 10% of women over 50 consumed less than two thirds of the RDA for iron from diet. For both men and women, all groups had median diet intakes below the RDA for magnesium. Forty percent of men and about half of women consumed less than two thirds of the RDA. These results indicate that many people in this well-educated, presumably well-nourished population did not consume adequate amounts of calcium, iron, magnesium, and zinc from diet. More women than men are at risk. Even those taking supplements did not consume adequate levels of some minerals.

Effect of calcium supplementation on bone loss in postmenopausal women

BACKGROUND

The use of calcium supplements slows bone loss in the forearm and has a beneficial effect on the axial bone density of women in late menopause whose calcium intake is less than 400 mg per day. However, the effect of a calcium supplement of 1000 mg per day on the axial bone density of postmenopausal women with higher calcium intakes is not known.

METHODS

We studied 122 normal women at least three years after they had reached menopause who had a mean dietary calcium intake of 750 mg per day. The women were randomly assigned to treatment with either calcium (1000 mg per day) or placebo for two years. The bone mineral density of the total body, lumbar spine, and proximal femur was measured every six months by dual-energy x-ray absorptiometry. Serum and urine indexes of calcium metabolism were measured at base line and after 3, 12, and 24 months.

RESULTS

The mean (+/- SE) rate of loss of total-body bone mineral density was reduced by 43 percent in the calcium group (-0.0055 +/- 0.0010 g per square centimeter per year) as compared with the placebo group (-0.0097 +/- 0.0010 g per square centimeter per year, P = 0.005). The rate of loss of bone mineral density was reduced by 35 percent in the legs (P = 0.02), and loss was eliminated in the trunk (P = 0.04). Calcium use was of significant benefit in the lumbar spine (P = 0.04), and in Ward's triangle the rate of loss was reduced by 67 percent (P = 0.04). Calcium supplementation had a similar effect whether dietary calcium intake was above or below the mean value for the group. Serum parathyroid hormone concentrations tended to be lower in the calcium group, as were urinary hydroxyproline excretion and serum alkaline phosphatase concentrations.

CONCLUSIONS

Calcium supplementation significantly slowed axial and appendicular bone loss in normal post-menopausal women.

The effects of calcium supplementation and exercise on bone density in elderly Chinese women

A randomized controlled trial was carried out to determine whether calcium supplementation and load-bearing exercise can increase or maintain bone mass in the elderly. Fifty Chinese women, aged 62-92 years, living in a hostel for the elderly in Hong Kong were randomized to enter one of four treatment groups: (I) calcium supplementation of 800 mg (as calcium lactate gluconate) daily; (II) load-bearing exercise four times a week plus a daily placebo tablet; (III) calcium supplementation daily and load-bearing exercise four times a week; (IV) a placebo tablet daily. The interventions went on for 10 months. The bone mineral density (BMD) was measured at three sites in the hip (femoral neck, Ward's triangle and intertrochanteric area) and the L2-4 level of the spine. The percentage change in BMD in 10 months was used as the main outcome measurement. The parathyroid hormone level and indices of bone metabolism were also measured before and after 10 months of intervention. The BMD at Ward's triangle and the intertrochanteric area increased significantly in subjects on calcium supplement (p less than 0.05), but there was no significant change at the spine and femoral neck. Exercise had no effect on bone loss at any site. However, the results of two-way analysis of variance showed a significant joint effect of calcium supplements and exercise at the femoral neck (p less than 0.05), but not at the other sites. The parathyroid hormone levels fell significantly in subjects on calcium supplements (p less than 0.01). Calcium supplement in the form of calcium lactate gluconate was adequately absorbed in elderly Chinese women with a calcium intake of less than 300 mg per day. It was effective in reducing bone loss at the hip, and there may be interaction effects with exercise in maintaining bone density.

Calcium intake and bone mass: a quantitative review of the evidence

The relationship between calcium intake and bone mass remains controversial. In this paper, the published research on this association is reviewed using the quantitative technique of meta-analysis. Selection of studies was based on defined eligibility criteria, and information relating to study design was recorded. Study results were converted, where necessary, to similar outcome measures so that direct comparison among studies was possible. A total of 37 eligible papers, representing 49 separate studies or parts of studies, were identified in the literature. Calcium had a consistent prevention effect on the rate of bone loss in the 12 studies of calcium supplements in postmenopausal women. This effect was greatest in studies in which the baseline calcium was low, supporting the idea of a threshold beyond which the effect of calcium is reduced. Cross-sectional studies showed a small but consistent positive correlation between calcium intake and bone mass. This association was greater in studies of premenopausal women. Some caution is needed in interpreting the results of this meta-analysis because of the poor quality of many of the studies reviewed. Nevertheless, the consistency of findings suggests that women in their early postmenopausal years will benefit from a high calcium intake.

Interaction of genetic and environmental influences on peak bone density

Risk of osteoporotic fracture in later life relates to both age and menopause-related bone loss but also to peak bone density achieved in early adulthood. Several studies have shown that genetic influences make a major contribution to variance in adult bone density, but environmental factors such as dietary calcium and physical activity also contribute a large proportion of observed variance in bone density. Previous hypotheses have suggested that the effect of certain environmental factors, such as hormonal and dietary influences, may be permissive to development of peak bone mass. Consideration of the evidence for the interaction between environmental influences, such as physical activity and nutrition, and genotype leads us to propose that environmental factors interact to allow or prevent full expression of bone density genotype. This expansion of the 'threshold' hypothesis can include the effects of sex, physical activity and dietary calcium in a model that allows more systematic study of the determinants of peak bone density and thereby more rational intervention to augment bone density in early adulthood.

A controlled trial of the effect of calcium supplementation on bone density in postmenopausal women

Background. The effectiveness of calcium in retarding bone loss in older postmenopausal women is unclear. Earlier work suggested that the women who were most likely to benefit from calcium supplementation were those with low calcium intakes. Methods. We undertook a double-blind, placebo-controlled, randomized trial to determine the effect of calcium on bone loss from the spine, femoral neck, and radius in 301 healthy postmenopausal women, half of whom had a calcium intake lower than 400 mg per day and half an intake of 400 to 650 mg per day. The women received placebo or either calcium carbonate or calcium citrate malate (500 mg of calcium per day) for two years. Results. In women who had undergone menopause five or fewer years earlier, bone loss from the spine was rapid and was not affected by supplementation with calcium. Among the women who had been postmenopausal for six years or more and who were given placebo, bone loss was less rapid in the group with the higher dietary calcium intake. In those with the lower calcium intake, calcium citrate malate prevented bone loss during the two years of the study; its effect was significantly different from that of placebo (P less than 0.05) at the femoral neck (mean change in bone density [+/- SE], 0.87 +/- 1.01 percent vs. -2.11 +/- 0.93 percent), radius (1.05 +/- 0.75 percent vs. -2.33 +/- 0.72 percent), and spine (-0.38 +/- 0.82 percent vs. -2.85 +/- 0.77 percent). Calcium carbonate maintained bone density at the femoral neck (mean change in bone density, 0.08 +/- 0.98 percent) and radius (0.24 +/- 0.70 percent) but not the spine (-2.54 +/- 0.85 percent). Among the women who had been postmenopausal for six years or more and who had the higher calcium intake, those in all three treatment groups maintained bone density at the hip and radius and lost bone from the spine. Conclusions. Healthy older postmenopausal women with a daily calcium intake of less than 400 mg can significantly reduce bone loss by increasing their calcium intake to 800 mg per day. At the dose we tested, supplementation with calcium citrate malate was more effective than supplementation with calcium carbonate.

Calcium supplementation of the diet: justified by present evidence

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