Dietary iron positively influences bone mineral density in postmenopausal women on hormone replacement therapy

The associations of dietary intakes of iron and calcium on change in bone mineral density (BMD) were examined over 1 y in healthy nonsmoking postmenopausal women (mean age 55.6 +/- 4.6 y) stratified by hormone replacement therapy (HRT) use (HRT, n = 116; no HRT, n = 112). BMD was measured at lumbar spine L(2)-L(4), trochanter, femur neck, Ward's triangle, and total body using dual-energy X-ray absorptiometry at baseline and 1 y. Mean nutrient intakes were assessed using 8-d diet records. All women received 800 mg/d of supplemental elemental calcium. Regression analyses examined the effects of iron and calcium intakes on BMD change adjusting for years past menopause, baseline BMD, weight change, exercise, and energy intake. The interaction of iron with calcium on BMD change was assessed using tertiles of iron and calcium intake and estimated marginal mean change in BMD. Iron was associated (P < or = 0.05) with greater positive BMD change at the trochanter and Ward's triangle in women using HRT. Calcium was associated (P < or = 0.05) with BMD change at the trochanter and femur neck for women not using HRT. In women using HRT in the lowest tertile of calcium intake, change in femur neck BMD increased linearly as iron intake increased. In women not using HRT, BMD increased in the women in the highest tertile of calcium intake. We conclude that HRT use appears to influence the associations of iron and calcium on change in BMD.     

膳食钙摄入量与青春前期女童骨量关系的研究

目的:研究青春前期女童膳食钙摄入量与骨量的关系,为指导合理钙营养提供科学依据。方法:采用双能X线骨密度测量仪测量年龄在10±1岁的194名青春前期女童全身及多位点骨密度和骨矿物质含量,采用食物频数及3d膳食询问法调查膳食钙摄入量,问卷法调查体力活动。结果:日均钙摄入量与所测各位点骨矿物质含量及骨密度均呈显著正相关;日均钙摄入量平均从257mg增加到759mg,不同位点的骨矿物质含量和骨密度分别增加13%～22%和3.6%～16%。结论:增加青春前期女童膳食钙摄入量有助于获得较高骨量和骨密度。     

钙摄入量对青春前期女童骨量增长的影响—两年随机干预实验

目的研究不同钙摄入量对于青春前期女童骨量增长的影响,为该人群钙适宜摄入量的修订提供科学依据。方法以年龄10.0±0.7岁的241名青春前期健康女童为对象,设计普通膳食组、牛奶补充组和钙剂补充组三组,总钙摄入量分别为600、900和1200mg/d,进行2年干预,采用多次称量及3d膳食询问法获得2年间日均膳食钙摄入量,使用双能X线骨密度仪测量干预前后全身、腰椎及近端股骨骨矿物密度和骨矿物含量。结果2年间三组的平均钙摄入量分别为552±61、864±139和1166±207mg/d;日均钙摄入量与全身、多位点骨矿物含量和骨矿物密度显著正相关;当日均钙摄入量达到864mg/d时,全身骨矿物含量增加值显著高于钙摄入量为552mg/d膳食组;当日均钙摄入量达到1166mg/d时,股骨颈骨矿物含量及骨矿物密度和腰椎骨矿物密度的增加值显著高于未达到1166mg/d的干预组。结论9～11.5岁的青春前期女童钙摄入量达到1166mg/d,全身特别是负重部位能获得较高骨矿物含量和骨矿物密度增长,提示青春前期钙适宜摄入量可能为1200mg/d。     

Calcium intake and bone mass development among Israeli adolescent girls.

OBJECTIVE: To determine the possible relationship between food and life style habits and bone health in adolescent Israeli females. METHODS: 2,000 adolescent Israeli Jewish and Arab high-school girls (mean age 14.5) completed a semi-quantitative food frequency questionnaire and a personal history questionnaire. 27 food components were calculated for each subject. Bone mineral content and density were determined for 112 subjects with calcium intake below 800 mg/day. RESULTS: Average calcium intake was found to be 1,260 mg/day, but 20% of all girls had a calcium intake below 800 mg/day. All low-energy diets were very low in calcium, as mean calcium intake per 1,000 calories was 411 128 grams. A large percentage of diets with less than 800 mg calcium were also deficient in phosphorus (95.2%), magnesium (84.8%). iron (90.5%) and zinc (100%). Due to differences in food sources. Jewish girls had more phosphorus in their diet, but less magnesium and iron compared to Arab girls. Calcium and zinc deficiencies in Jewish and Arab diets were similar. A negative correlation was found between body mass index (BMI) and age at menarche for all girls in the study. Bone mineral density (BMD) measured for girls with calcium intake below 800 mg/day distributed normally around the average when compared to age matched controls despite their low calcium intake. There was a strong positive correlation between BMD and bone mineral content (BMC) at all sites and body weights. CONCLUSIONS: Low calcium intake, other nutritional deficiencies and delayed menarche due to low-energy diet in the growing period and in adolescence may prevent the formation of healthy bones. There is no evidence of lower bone mass among the low calcium intake group in the study population at this stage. It remains to be documented if the window of opportunity for optimal bone accretion for this group will be missed in the future. possibly leading to increased risk of osteoporosis.     

Dairy intakes affect bone density in the elderly

BACKGROUND: Race and sex differences in the effect of diet on bone mineral density (BMD) at the hip in the elderly are unknown. OBJECTIVES: This study related cross-sectional nutrient and dairy product consumption to hip BMD in white and black men and women aged >60 y and evaluated the influence of nutrient and dairy product consumption on changes in BMD in a white cohort participating in a calcium, vitamin D, or placebo trial. DESIGN: The Health Habits and History Questionnaire was used in 289 white women and 116 white men who participated in the trial and in 265 black women and 75 black men to predict total hip and femoral neck BMD or changes in BMD. RESULTS: Blacks had higher calcium intakes than did whites (700 and 654 mg/d, respectively; P = 0.0094), and men had higher calcium intakes than did women (735 and 655 mg/d, respectively; P = 0.0007). For men, the correlation between total hip BMD and dairy calcium intake after adjustment for age, race, and weight was 0.23 (P < 0.005); this relation was not significant in women (r = 0.02, P = 0.12). Similar results were found for femoral neck BMD. In the longitudinal study, calcium supplementation reduced bone loss from the total hip and femoral neck in those who consumed <1.5 servings of dairy products/d and were <72 y old. CONCLUSIONS: Cross-sectional results indicated that higher dairy product consumption is associated with greater hip BMD in men, but not in women. Calcium supplementation protected both men and women from bone loss in the longitudinal study of whites.     

Correlates of forearm bone mass among women during maximal bone mineralization

The distribution and correlates of bone mass among women ages 20-35 were studied. During young adulthood, bone mass reaches its maximum level and appears to stabilize. Factors that establish the individual's relative position in this plateau period may influence the ultimate expression of bone loss with aging. Mid-distal radial bone mass was measured in a geographically defined population of 86 women in two rural, demographically similar communities in Iowa. The water supplies provided 55 and 375 mg/liter of elemental calcium, generating significantly different mean community dietary calcium intakes of 871 and 1,233 mg/day, respectively. Bone mass was measured by single-beam photon densitometry and correlated with data from physical measurements, medical history, and reported nutritional intake. In evaluating the joint effect of variables in a multiple regression procedure, forearm bone mass was negatively and significantly associated with alcohol consumption (P = 0.0327) and with a first pregnancy prior to age 20 (P = 0.0250). There was a trend for current calcium intake estimated from 24-hr recall to be positively associated with bone mass (P = 0.0816). Because the 24-hr recall is characterized by significant error due to daily variability of an individual's intakes, a more general calcium intake was estimated from food frequency. Women whose estimated intake of calcium from food frequency was greater than 800 mg/day, the Recommended Daily Allowance, had significantly greater bone mass than women whose intake was estimated to be less than 800 mg/day (P = 0.0053). No relationship was observed with oral contraceptive use, parity, breastfeeding practices, smoking behavior, or measures of physical activity.     

Correlates of mid-radius bone density among postmenopausal women: a community study

We surveyed mid-radius bone density in a geographically-defined population of 324 women, 55-80 years old from two small, demographically-similar communities whose water supply provided 60 mg/l and 375 mg/l of elemental calcium. Mean community calcium intakes were 964 mg/day and 1329 mg/day respectively. Bone density, measured by photon densitometry, was correlated with physical measurements, medical history, and reported nutritional intake. Mid-radius bone density decreased with age while the following additional factors were independently and positively associated with bone density: humeral muscle area (p = 0.0001), extended estrogen use (p = 0.0004), thiazide use (p = 0.0029), and vitamin D intake (p = 0.0104). Estimated total calcium intake alone did not significantly correlate with bone density; however, mean bone density was significantly greater in persons whose calcium intake was greater than 800 mg/day, consumed concurrently with vitamin D in amounts greater than 400 IU (p = 0.0342), the Recommended Daily Allowance of these two nutrients.     

Calcium requirements: new estimations for men and women by cross-sectional statistical analyses of calcium balance data from metabolic studies

BACKGROUND: Low intakes of calcium are associated with an increased risk of both osteoporosis and cardiovascular disease. OBJECTIVE: To provide new estimates of the average calcium requirement for men and women, we determined the dietary calcium intake required to maintain neutral calcium balance. DESIGN: Calcium balance data [calcium intake -(fecal calcium + urinary calcium)] were collected from 155 subjects [women: n = 73; weight: 77.1 +/- 18.5 kg; age: 47.0 +/- 18.5 y (range: 20-75 y); men: n = 82; weight: 76.6 +/- 12.5 kg; age: 28.2 +/- 7.7 y (range: 19-64 y)] who participated in 19 feeding studies conducted in a metabolic unit. Balance data from the final 6-12 d of each dietary period (minimum length:18 d) of each study (1-9 observations per subject) were analyzed. Data were excluded if individual intakes of magnesium, copper, iron, phosphorus, or zinc fell below the estimated average requirements or exceeded the 99 th percentile of usual intakes from the 1994 Continuing Survey of Food Intakes by Individuals (for iron, above the upper limit). Daily intakes of calcium ranged between 415 and 1740 mg. The relation between intake and output was examined by fitting random coefficient models. Coefficients were included to test for sex and age differences. RESULTS: The models predicted a neutral calcium balance [defined as calcium output (Y) equal to calcium intake (C)] at intakes of 741 mg/d [95% prediction interval (PI): 507, 1035; Y = 148.29 + 0.80C], 9.4 mg kg body wt(-1) d(-1) [95% PI: 6.4, 12.9; Y = 1.44 + 0.85C], or 0.28 mg kcal(-1) d(-1) [95% PI: 0.19, 0.38; Y = 0.051 + 0.816C]. Neither age nor sex affected the estimates when calcium intakes were expressed as mg/d or as mg kg body wt(-1) d(-1). CONCLUSION: The findings suggest that the calcium requirement for men and women is lower than previously estimated.     

First Quantification of Calcium Intake from Calcium-Dense Dairy Products in Dutch Fracture Patients (The Delft Cohort Study)

Recommendations for daily calcium intake from dairy products are variable and based on local consensus. To investigate whether patients with a recent fracture complied with these recommendations, we quantified the daily dairy calcium intake including milk, milk drinks, pudding, yoghurt, and cheese in a Dutch cohort of fracture patients and compared outcomes with recent data of a healthy U.S. cohort (80% Caucasians). An observational study analyzed dairy calcium intakes of 1526 female and 372 male Dutch fracture patients older than 50. On average, participants reported three dairy servings per day, independently of age, gender or population density. Median calcium intake from dairy was 790 mg/day in females and males. Based on dairy products alone, 11.3% of women and 14.2% of men complied with Dutch recommendations for calcium intake (adults ≤ 70 years: 1100 mg/day and >70 years: 1200 mg/day). After including 450 mg calcium from basic nutrition, compliance raised to 60.5% and 59.1%, respectively, compared to 53.2% in the U.S. cohort. Daily dairy calcium intake is not associated with femoral neck bone mineral density (BMD) T-scores or WHO Fracture Assessment Tool (FRAX) risk scores for major fracture or hip fracture. However, when sub analyzing the male cohort, these associations were weakly negative. The prevalence of maternal hip fracture was a factor for current fracture risks, both in women and men. While daily dairy calcium intake of Dutch fracture patients was well below the recommended dietary intake, it was comparable to intakes in a healthy U.S. cohort. This questions recommendations for adding more additional dairy products to preserve adult skeletal health, particularly when sufficient additional calcium is derived from adequate non-dairy nutrition.     

Protein intake: effects on bone mineral density and the rate of bone loss in elderly women

BACKGROUND: The role of dietary protein in bone metabolism is controversial. OBJECTIVE: We investigated the associations of dietary protein intake with baseline bone mineral density (BMD) and the rate of bone loss over 3 y in postmenopausal elderly women. DESIGN: Women aged 65-77 y (n = 489) were enrolled in an osteoporosis intervention trial. We studied the associations of protein intake as a percentage of energy with baseline BMD and the rate of bone loss in 96 women in the placebo group (n = 96). We also examined the effect of the interaction of dietary calcium intake with protein intake on BMD. RESULTS: In the cross-sectional study, a higher intake of protein was associated with higher BMD. BMD was significantly higher (P < 0.05) in the spine (7%), midradius (6%), and total body (5%) in subjects in the highest quartile of protein intake than in those in the lower 2 quartiles. This positive association was seen in women with calcium intakes > 408 mg/d. There was no significant effect of protein intake on hip BMD. In the longitudinal study of the placebo group, there was no association between protein intake and the rate of bone loss. CONCLUSIONS: The highest quartile of protein intake (: 72 g/d) was associated with higher BMD in elderly women at baseline only when the calcium intake exceeded 408 mg/d. In the longitudinal study, no association was seen between protein intake and the rate of bone loss, perhaps because the sample size was too small or the follow-up period of 3 y was not long enough to detect changes.     

Calcium supplementation provides an extended window of opportunity for bone mass accretion after menarche

BACKGROUND: High calcium intakes during adolescence may increase bone acquisition. The magnitude of the effect of dietary calcium supplementation and the timing of its administration to achieve significant effects on bone health are still incompletely defined. OBJECTIVE: The objective of this study was to assess the effect of calcium supplementation on bone mass accretion in postmenarcheal adolescent girls with low calcium intakes. DESIGN: A double-blind, placebo-controlled calcium supplementation study was implemented. One hundred girls with a mean (+/- SD) age of 14 +/- 0.5 y with habitual calcium intakes < 800 mg/d completed a 12-mo protocol. The treatment group received a daily supplement containing 1000 mg elemental calcium. Bone mineral density (BMD) and bone mineral content (BMC) of the total body, lumbar spine, and femoral neck were determined at inclusion, 6 mo, and 12 mo. Also measured were serum concentrations of biochemical markers of bone turnover (osteocalcin and deoxypyridinoline), parathyroid hormone, and vitamin D. RESULTS: The calcium-supplemented group had greater accretion of total-body BMD and lumbar spine BMD but not BMC than did the control group. Calcium supplementation appeared selectively beneficial for girls who were 2 y postmenarcheal. Calcium supplementation significantly decreased bone turnover and decreased serum parathyroid hormone concentrations. CONCLUSION: Calcium supplementation of postmenarcheal girls with low calcium intakes enhances bone mineral acquisition, especially in girls > 2 y past the onset of menarche.     

不同钙摄入量对青年男性骨密度的影响

目的 探讨不同钙摄入量对我国青年男性骨密度的影响，为进一步研究制定我国居民钙的适宜摄入量提供科学依据。方法 为期13个月的双盲对照干预研究。将某军校男学员155人，平均年龄21．3岁，随机分为4组，以干预前全身骨密度及膳食钙摄入量为基线，进行不同剂量碳酸钙片营养干预，使总钙摄入量分别达到约500、800、1000及1200mg／d，每片钙片中均强化60IU的维生素D。干预前后分别使用食堂记帐法、称重法和24小时记录法了解膳食摄入，双能X线骨密度仪（DEXA）测定全身、腰椎和前臂的骨密度。结果 4组平均摄入的膳食钙加上补充钙的中位数分别是514mg／d（1组）、821mg／d（2组）、987mg／d（3组）、1209mg／d（4组）。实验前后各部位骨密度增加值的组间比较分析显示，第2、3、4组全身、前臂、骨盆的骨密度增加值显著高于第1组，且三组之间无显著性差异；第3、4组下肢骨密度增加值显著高于第1、2组，且3、4组之间无显著性差异。结论 随着钙摄入量的增加，青年男性全身各部位骨密度增加，当钙摄入量达到约1000mg／d时，全身、前臂、骨盆和下肢骨密度增加值达到最大，再增加钙摄入至1200mg／d时，骨密度不再显著增加。提示我国青年男性钙的适宜摄入量可能在1000mg／d左右。     

Dietary influences on bone mass and bone metabolism: further evidence of a positive link between fruit and vegetable consumption and bone health?

BACKGROUND: The role of nutritional influences on bone health remains largely undefined because most studies have focused attention on calcium intake. OBJECTIVE: We reported previously that intakes of nutrients found in abundance in fruit and vegetables are positively associated with bone health. We examined this finding further by considering axial and peripheral bone mass and markers of bone metabolism. DESIGN: This was a cross-sectional study of 62 healthy women aged 45-55 y. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry at the lumbar spine and femoral neck and by peripheral quantitative computed tomography at the ultradistal radial total, trabecular, and cortical sites. Bone resorption was calculated by measuring urinary excretion of pyridinoline and deoxypyridinoline and bone formation by measuring serum osteocalcin. Nutrient intakes were assessed by using a validated food-frequency questionnaire; other lifestyle factors were assessed by additional questions. RESULTS: After present energy intake was controlled for, higher intakes of magnesium, potassium, and alcohol were associated with higher total bone mass by Pearson correlation (P < 0.05 to P < 0.005). Femoral neck BMD was higher in women who had consumed high amounts of fruit in their childhood than in women who had consumed medium or low amounts (P < 0.01). In a regression analysis with age, weight, height, menstrual status, and dietary intake entered into the model, magnesium intake accounted for 12.3% of the variation in pyridinoline excretion and 12% of the variation in deoxypyridinoline excretion. Alcohol and potassium intakes accounted for 18.1% of the variation in total forearm bone mass. CONCLUSION: The BMD results confirm our previous work (but at peripheral bone mass sites), and our findings associating bone resorption with dietary factors provide further evidence of a positive link between fruit and vegetable consumption and bone health.     

Potassium, magnesium, and fruit and vegetable intakes are associated with greater bone mineral density in elderly men and women

BACKGROUND: Osteoporosis and related fractures will be growing public health problems as the population ages. It is therefore of great importance to identify modifiable risk factors. OBJECTIVE: We investigated associations between dietary components contributing to an alkaline environment (dietary potassium, magnesium, and fruit and vegetables) and bone mineral density (BMD) in elderly subjects. DESIGN: Dietary intake measures were associated with both cross-sectional (baseline) and 4-y longitudinal change in BMD among surviving members of the original cohort of the Framingham Heart Study. Dietary and supplement intakes were assessed by food-frequency questionnaire, and BMD was measured at 3 hip sites and 1 forearm site. RESULTS: Greater potassium intake was significantly associated with greater BMD at all 4 sites for men and at 3 sites for women (P < 0.05). Magnesium intake was associated with greater BMD at one hip site for both men and women and in the forearm for men. Fruit and vegetable intake was associated with BMD at 3 sites for men and 2 for women. Greater intakes of potassium and magnesium were also each associated with less decline in BMD at 2 hip sites, and greater fruit and vegetable intake was associated with less decline at 1 hip site, in men. There were no significant associations between baseline diet and subsequent bone loss in women. CONCLUSION: These results support the hypothesis that alkaline-producing dietary components, specifically, potassium, magnesium, and fruit and vegetables, contribute to maintenance of BMD.     

The protective effect of calcium on bone mass in postmenopausal women with high selenium intake

Objective

Nutritional factors, especially the two essential nutrients calcium and vitamin D, have been shown to play an important role in bone health. We wanted to determine the possible protective effect of calcium intake in adequate amounts on bone mass as assessed by quantitative ultrasound in postmenopausal women who also have a high intake of selenium.

Setting

Health district of Cáceres, Spain.

Participants and Study Design

335 postmenopausal women aged 60.9 (SD = 8.1) years. Women were stratified based on the vitamin D, vitamin E, calcium intake and the calcium/protein and calcium/phosphorous index.

Measurements

Bone status (Ad-SoS measured at the phalanges) was assessed with an ultrasound device model DBM Sonic 1200R. Food intake was quantified using dietetic scales, measuring cups, and spoons based on 7 days of diet records. Urine samples were collected the morning of testing after an overnight fast. Venous blood samples for the hematological and biochemical studies were also obtained in the fasting state.

Results

In the group of women with Ca intake < 800 mg / d we found a significant and negative relationship between Ad-SoS with age (?? = ?4.020, F = 23.327) and selenium intake (?? = ?0.419, F = 10.067), as well as a positive relationship with Ca intake (?? = 0.104 and F = 7.084) (p <0.0001 in all). In the group of women with Ca intake > 800 mg / d, age has a significant and negative relationship (?? = ?4.829 and F = 106.745), whereas folic acid intake has a significant and positive relationship (?? = 0.047 and F = 5.858) (p <0.0001 in both).

Conclusion

Elevated selenium intake negatively affects bone mass measurements in postmenopausal women over the age of 51 but only if calcium intake is also less than 800 mg / day. When calcium intake is greater than 800 mg/day, selenium did not appear to affect bone mass.     

Nutritional intake of pre- and postmenopausal Australian women with special reference to calcium

Dietary factors, in particular calcium intake, have been implicated as risk factors in the aetiology of osteoporosis. In Australia there are few published data on the calcium intake of either premenopausal or postmenopausal women. The dietary intakes of calcium and 14 other nutrients were measured in 82 premenopausal and in 65 postmenopausal Caucasian women aged between 23 and 75 years. We found that 75 per cent of the postmenopausal and 61 per cent of the premenopausal women failed to meet the Australian recommended dietary allowance (RDA) for calcium of 1000 mg and 800 mg/d respectively. Moreover, 29 per cent of the postmenopausal women consumed less than 500 mg/d of calcium. Other nutrients including zinc, magnesium and iron were also deficient for many subjects. These data are relevant to the evaluation of dietary factors in the aetiology of osteoporosis.     

膳食钙不足对香港青少年先天性脊柱侧凸全身骨质密度偏低的影响(英文)

青少年先天性脊柱侧凸 (AIS)是一种主要影响女孩的脊柱严重三维畸形病。在香港有 3 %～ 4%的发病率 ,AIS的病人同时发现患有全身性的骨密度偏低现象。本文试图研究是否低骨矿物质密度 (BMD)与AIS病人钙摄入量有关。以 11～ 16岁 582名AIS患者和 2 0 6名健康对照人群为研究对象。面积骨矿物质密度 (aBMD)和体积骨矿物质密度 (vBMD)分别用DXA(Norland XR 3 6)和PQCT(Densiscan 10 0 0 )检测。钙和其它营养素摄入量用食物频率法评价。受试者钙绝对摄入量低 (<50 0mg d)。患AIS少女平均钙摄入量显著高于对照组少女 [(441± 3 4 4 )mg dvs.(3 90± 2 81)mg d ,P =0 0 15] ,11～ 16岁AIS患者大多数骨骼测定点BMD显著低于同龄对照组 (P≤ 0 0 5)。AIS患者与对照组BMD的差异程度随着年龄的增长而增加。 15～ 16岁年龄组AIS患者中钙摄入量与在大多数骨骼测定点测得的BMD有显著相关性 ,而在对照组中没有发现这种相关性。经多因素分析 ,在控制干扰变量的情况下 ,预测BMD的变化 ,钙摄入量是一个非依从性决定因素。结果提示 ,AIS患者绝对钙摄入量低 ,在各年龄组青少年中各个骨骼测定点测得的BMD ,AIS患者组均低于对照组。只有在AIS患者中钙摄入量与BMD有相关性 ,而健康的对照中没有相关性。这表明钙摄入量对AIS患者     

Spinal bone density and calcium intake in healthy postmenopausal women

Dietary calcium intake and bone mineral density (BMD) of the lumbar spine (L2-L4) were determined in 131 healthy free-living postmenopausal women (aged 64.7 +/- 7.6 y, means +/- SD). The calcium consumption for the total population was 606 +/- 302 mg/d. Subjects consuming less than the population mean of dietary calcium had significantly lower BMDs than did subjects with intakes above the mean (P less than 0.009); these two groups did not differ in basic demographic characteristics. Additional analyses using a stepwise univariate regression model demonstrated that BMD was significantly associated with body weight (P less than 0.001) and dietary calcium intake (P less than 0.02). These data support the hypothesis that dietary calcium intake is a determinant of skeletal health in postmenopausal women.     

Calcium intake influences the association of protein intake with rates of bone loss in elderly men and women

BACKGROUND: There is currently no consensus on the effect of dietary protein intake on the skeleton, but there is some indication that low calcium intakes adversely influence the effect of dietary protein on fracture risk. OBJECTIVE: The objective of the present study was to determine whether supplemental calcium citrate malate and vitamin D influence any associations between protein intake and change in bone mineral density (BMD). DESIGN: Associations between protein intake and change in BMD were examined in 342 healthy men and women (aged > or = 65 y) who had completed a 3-y, randomized, placebo-controlled trial of calcium and vitamin D supplementation. Protein intake was assessed at the midpoint of the study with the use of a food-frequency questionnaire and BMD was assessed every 6 mo by dual-energy X-ray absorptiometry. RESULTS: The mean (+/-SD) protein intake of all subjects was 79.1 +/- 25.6 g/d and the mean total calcium intakes of the supplemented and placebo groups were 1346 +/- 358 and 871 +/- 413 mg/d, respectively. Higher protein intake was significantly associated with a favorable 3-y change in total-body BMD in the supplemented group (in a model containing terms for age, sex, weight, total energy intake, and dietary calcium intake) but not in the placebo group. The pattern of change in femoral neck BMD with increasing protein intake in the supplemented group was similar to that for the total body. CONCLUSION: Increasing protein intake may have a favorable effect on change in BMD in elderly subjects supplemented with calcium citrate malate and vitamin D.     

Dietary acid load is not associated with lower bone mineral density except in older men

High dietary acid load may be detrimental to bone mineral density (BMD), although sufficient calcium intake might neutralize this effect. In observational studies, the association between BMD and dietary acid load, estimated by net endogenous acid production (NEAP) and potential renal acid load (PRAL), has been inconsistent, and the potential modifying effect of calcium intake has not been assessed. We therefore examined the cross-sectional associations of estimated NEAP and PRAL with BMD in the Framingham Osteoporosis Study. We hypothesized that higher estimated NEAP and PRAL would be associated with lower BMD, but only among those with total calcium intake < 800 mg/d. BMD of the femoral neck and lumbar spine was measured, and estimated NEAP and PRAL were calculated via FFQ among 1069 Framingham Original (1988-1989, 1992-1993; 62% women, mean age 76 y) and 2919 Offspring (1996-2001; 56% women, mean age 60 y) cohort participants. Cohort- and sex-specific ANCOVA was used to calculate multivariable-adjusted mean BMD for estimated NEAP and PRAL quartiles. Assuming no uncontrolled confounding, estimated NEAP, but not PRAL, was inversely associated with femoral neck BMD (P-trend = 0.04) in Original cohort men, whereas neither was associated with lumbar spine BMD. Estimated NEAP and PRAL were not associated with BMD at any site among Original cohort women or Offspring cohort men and women. There were no significant interactions between either estimated NEAP or PRAL and total calcium intake. These results suggest that, with a possible exception of older men, dietary acid load does not have a measureable negative effect on bone health, regardless of total calcium intake.