Prevalence and seasonal variation of hypovitaminosis D and its relationship to bone metabolism in community dwelling postmenopausal Hungarian women

Hypovitaminosis D can result in low bone mass. The prevalence of hypovitaminosis D has public health implications, especially where data are lacking. Since diet and sunlight are the two souces of vitamin D, the results obtained in one geographical region may not be universally applicable. The aim of this study is to characterize the prevalence and seasonal variation of hypovitaminosis D and its relationship to bone metabolism in community dwelling postmenopausal Hungarian women. We determined serum levels of 25-hydroxyvitamin D (25-OH-D), PTH, osteocalcin (OC), degradation products of C-terminal telopeptides of type-I collagen (CTx), dietary calcium intake and BMD at L2–L4 lumbar spine (LS) and femur neck (FN) in 319 randomly selected ambulatory postmenopausal women. The prevalence of hypovitaminosis D (serum 25-OH-D50 nmol/l) was 56.7%. On comparing patients with normal and low 25-OH-D, a significant difference was found in age (61.6±8.5 years versus 67.3±9.9 years; P<0.001), PTH (3.9±1.9 pmol/l versus 4.3±2.7 pmol/l; P<0.05), FN BMD (0.802±0.123 g/cm² versus 0.744±0.125 g/cm²; P<0.001) and dietary calcium intake (714.4±199.4 g/day versus 607.9±233 g/day; P<0.001). Osteoporotic patients had a significantly lower 25-OH-D (37.6±19.8 nmol/l versus 56.4±24 nmol/l; P<0.001) and dietary calcium intake (519.2±244.5 mg/day versus 718.2±164.3 mg/day; P<0.001). After controlling for all other variables, 25-OH-D was found to be significantly associated with age, the average hours of sunshine in the 3 months prior to 25-OH-D level determination and dietary calcium intake (r ²=0.190; P<0.001). For FN BMD, significant independent predictors were age, body mass index, 25-OH-D and dietary calcium intake (r ²=0.435; P<0.001). The prevalence of hypovitaminosis D during spring, summer, autumn and winter was 71%, 46.3%, 49.4% and 56.7%, respectively. There was significant seasonal variation in 25-OH-D, PTH, OC, calcium intake and FN BMD. There is a high prevalence of hypovitaminosis D in healthy postmenopausal Hungarian women, and FN BMD is associated with serum 25-OH-D and dietary calcium intake.     

Dietary Calcium and Serum 25‐Hydroxyvitamin D Status in Relation to BMD Among U.S. Adults

A higher calcium intake is still the primary recommendation for the prevention of osteoporosis, whereas vitamin D deficiency is often not addressed. To study the relative importance of dietary calcium intake and serum 25‐hydroxyvitamin D [25(OH)D] status in regard to hip BMD, 4958 community‐dwelling women and 5003 men ≥20 yr of age from the U.S. NHANES III population‐based survey were studied. Calcium supplement users and individuals with a prior radius or hip fracture were excluded. We calculated standardized means for BMD by quartiles of sex‐specific calcium intake for three 25(OH)D categories (<50, 50–74, and 75+ nM) among men and women, separately controlling for other important predictors of BMD. A higher calcium intake was significantly associated with higher BMD (p value for trend: p = 0.005) only for women with 25(OH)D status <50 nM, whereas calcium intake beyond the upper end of the lowest quartile (>566 mg/d) was not significantly associated with BMD at 25(OH)D concentrations >50 nM. Among men, there was no significant association between a higher calcium intake beyond the upper end of the lowest quartile (626 mg/d) and BMD within all 25(OH)D categories. Among both sexes, BMD increased stepwise and significantly with higher 25(OH)D concentrations (<50, 50–74, 75+ nM; p value for trend: women < 0.0001; men = 0.0001). Among men and women, 25(OH)D status seems to be the dominant predictor of BMD relative to calcium intake. Only women with 25(OH)D concentrations <50 nM seem to benefit from a higher calcium intake.     

Prophylactic calcium and vitamin D treatments in steroid-treated children with nephrotic syndrome

Steroid treatment has several side effects, including the deterioration of the bone and mineral metabolism in children with nephrotic syndrome. This randomized prospective study was conducted to determine the effects and prophylactic role of calcium plus vitamin D treatment on bone and mineral metabolism in children receiving prednisolone treatment. 40 children (27 boys and 13 girls) with NS (18 new onset and 22 relapsing) were included in the study. Their mean age was 4.6±1.8 years. All patients received prednisolone treatment (2 mg/kg/day for 4 weeks followed by alternate days at the same dose for 4 weeks). The patients were randomized into treatment (vitamin D 400 IU plus calcium 1 g daily) and non-treatment groups. Bone mineral density, serum Ca, P, alkaline phosphatase and urinary Ca and P excretions were analyzed at the beginning and 2 months after the treatment. The XR36 Norland device was used for bone mineral density analysis. Bone mineral density was significantly decreased in both the treatment (0.54±0.15 to 0.51±0.1 g/cm², P =0.001) and non-treatment (0.52±0.18 to 0.45±0.16 g/cm², P <0.001) group. But the percentage of bone mineral density decrease was found to be significantly lower in the treatment group than in the non-treatment group (4.6±2.1% vs. 13.0±4.0%, respectively; P <0.001). Serum calcium and urinary calcium excretion increased in the treatment group (8.0±1.0 to 10.0±0.5 mg/dl and 1.1±0.5 to 3.2±1.0 mg/kg/day) and non-treatment group (8.1±0.8 to 10.0±0.6 mg/dl and 1.4±0.9 to 3.8±3.3 mg/kg/day) after prednisolone treatment (P <0.001). Steroid treatment decreases bone mineral density in children with nephrotic syndrome. Vitamin D plus calcium therapy at the current doses reduces but does not completely prevent bone loss, with no additional adverse effects.     

Urinary calcium excretion in healthy school children

Two hundred and twenty Argentinian primary school children (122 boys, 98 girls, aged 6 – 13 years) were studied to establish reference values of 24-h urinary calcium excretion (UCa) and calcium/creatinine ratio (Ca/Cr) in 24-h urine collections and in first-morning urine samples. Mean UCa excretion was 2.05±1.40 mg/kg per day and the 95th percentile was 4.74 mg/kg per day. UCa excretion was higher in boys than girls (2.33±1.47 and 1.70±1.24 mg/kg per day respectively, P <0.001). Statistically significant differences were found between the 6- to 9-year and the 10- to 13-year age groups (2.37±1.49 vs. 1.73±1.25 mg/kg per day, P <0.001). Mean Ca/Cr ratios in 24-h collections and in first-morning urine samples were 0.129±0.086 and 0.105±0.079 for the group overall (P <0.001). The Ca/Cr ratio in the first-morning urine sample correlated poorly with the 24-h calcium excretion, suggesting that the Ca/Cr ratio in first-morning urine samples cannot replace the 24-h measurement. Received December 22, 1995; received in revised form June 17, 1996; accepted June 18, 1996     

High-calcium intake abolishes hyperoxaluria and reduces urinary crystallization during a 20-fold normal oxalate load in humans

Background: The aim of the study was to test whether increasing dietary calcium intake lowers intestinal oxalate absorption and thereby prevents hyperoxaluria and urinary crystallization during a 20-fold normal oxalate load in healthy subjects. Methods: Fourteen healthy male volunteers (age 23-44 years, BMI 21.5-27.7 kg/m²) collected 24-h urines while on free choice diet as well as on two standardized diets. The latter contained 2545 kcal, 2500 ml of mineral water, 102 g of protein, 13.6 g of sodium chloride and 2220 mg of oxalate ( 20-fold content of an average diet). Subjects were studied twice while on the standardized diet, once while eating a normal amount of calcium (1211 mg/day, oxalate-rich, diet), and once while eating 3858 mg of calcium /day (calcium and oxalate-rich diet). Results: Compared with the free-choice diet (322±36 &mgr;mol/d), UOx X V increased to 780±722 &mgr;mol/d on the oxalate-rich diet (P=0.001) and fell again to 326±31 &mgr;mol/d on calcium and oxalate-rich diet (P=0.001 vs oxalate-rich diet). Urinary glycolate (a metabolic precursor of Ox) always remained below the upper limit of the normal range and did not change between different diets, indicating that changes in UOx x V reflect respective variations in intestinal absorption of Ox. UCa x V was 4.60±0.45 mmol/d on the free choice diet and 3.20±0.32 mmol/d on the oxalate-rich diet (P=0.011 vs free-choice diet); it increased to 7.28±0.74 mmol/d on the calcium- and oxalate-rich diet (P=0.001 vs free-choice and oxalate-rich diets). As indicated by the AP (CaOx) index (Tiselius), urinary supersaturation did not vary significantly between the three diets. In freshly voided morning urines (studied in 8/14 subjects) on the oxalate-rich diet, CaOx crystals or crystal aggregates of up to 80 &mgr;m diameter were found in 5/8 urines, whereas this never occurred on the free-choice diet and only once on the calcium- and oxalate-rich diet. Conclusion: Increasing calcium intake while eating Ox-rich food prevents dietary hyperoxaluria and reduces CaOx crystallization in healthy subjects. This further illustrates that dietary counseling to idiopathic calcium-stone formers should ensure sufficient calcium intake, especially during oxalate-rich meals.     

Development of a tool for the assessment of calcium and vitamin D intakes in clinical settings

Summary  The study aim was to develop a tool (software and ruler) to assess the dietary calcium and vitamin D intakes in Portugal, and evaluate the usefulness of non-dietary variables as intake predictors. Our findings indicated that is possible to estimate both using three and six food items, respectively, and non-dietary predictors. Introduction  The study aim was to develop a tool to assess the dietary calcium and vitamin D intakes in Portugal, and evaluate the usefulness of non-dietary variables as predictors. Methods  Trained interviewers collected information of 2,414 adults of Porto, Portugal, using a structured questionnaire and a validated semi-quantitative food frequency questionnaire (FFQ). Food items with the highest contribution to the total intake and non-dietary predictors (gender, age and body mass index (BMI)) were selected for the tool. Different statistical approaches were used to predict the intake. A Bland–Altman plot compared the predictions from the tool and the full FFQ. Results  The items selected to predict intake were milk (38%), cheese (12%), yogurt (10%) and gender for calcium and oily fish (39%), canned fish (9%), white fish (7%), eggs (5%), red meat (5%), age and BMI for vitamin D. The Bland–Altman plot showed that the mean differences were 0.0 (limits of agreement = [-220.67; 220.77]) mg/day and 0.0 (limits of agreement = [-1.03; 1.05]) μg/day, respectively for calcium and vitamin D. Conclusion  The equations estimated by the best statistical model to predict the calcium and vitamin D intake allowed for the design of a software and a circular ruler useful in clinical settings.     

Bone Size and Bone Mass in 10-Year-Old Danish Children: Effect of Current Diet

Lifestyle factors, such as diet, are believed to be involved in modifying bone health, although the results remain controversial, particularly in children and adolescents. The objective of the study was to identify associations between dietary factors and whole body bone measurements in 10-year-old children. The study was a cross-sectional analysis of a random sample of 105 healthy Danish children, aged 10 years (9.97 ± 0.09). Whole body bone mineral content (BMC) and bone area (BA) were determined by dual-energy X-ray absorptiometry. The influence of diet (7 day food records) on BMC and BA were examined in bi- and multivariate analyses. The mean intakes of calcium, protein, phosphorus and sodium were 1226 mg, 78 g, 1523 mg and 3.3 g, respectively. In bivariate analyses, BMC and BA were strongly positively correlated with height (p<0.001) and weight (p<0.001), and with intakes of energy (p<0.005) and several nutrients. BMC was adjusted for size by including BA, height and weight in the multiple linear regression, and BA was adjusted for size by including height and weight in the multiple linear regression. In multivariate analyses, size-adjusted BMC was positively associated with calcium intake (p = 0.02). Size-adjusted BA was positively associated with dietary protein (p = 0.003), and negatively associated with intakes of sodium (p = 0.048) and phosphorus (p = 0.01). In conclusion, calcium intake was positively associated with bone mineralization. There was a positive association between protein and BA, while for phosphorus and sodium the association was negative. The findings suggest that in addition to calcium, the intake of other nutrients influences bone development in prepubertal children. Received: 31 December 1999 / Accepted: 23 June 2000     

Coffee, tea and caffeine consumption in relation to osteoporotic fracture risk in a cohort of Swedish women

Introduction Consumption of coffee and tea, and total intake of caffeine has been claimed to be associated with osteoporotic fracture risk. However, results of earlier studies lack consistency. Methods We examined this relation in a cohort of 31,527 Swedish women aged 40-76 years at baseline in 1988. The consumption of coffee, caffeinated tea and the intake of caffeine were estimated from a self-administered food frequency questionnaire (FFQ). Multivariate-adjusted hazards ratios (HRs) of fractures with 95% confidence intervals (95% CIs) were estimated by Cox proportional hazards models. Results During a mean follow-up of 10.3 years, we observed 3,279 cases with osteoporotic fractures. The highest (>330 mg/day) compared with the lowest (<200 mg/day) quintile of caffeine intake was associated with a modestly increased risk of fracture: HR 1.20 (95% CI: 1.07–1.35). A high coffee consumption significantly increased the risk of fracture (p for trend 0.002), whereas tea drinking was not associated with risk. The increased risk of fracture with both a high caffeine intake and coffee consumption was confined to women with a low calcium intake (<700 mg/day): HR 1.33 (95% CI: 1.07–1.65) with ≥4 cups (600 ml)/day of coffee compared to <1 cup (150 ml)/day. The same comparison but risk estimated for women with a high propensity for fractures (≥2 fracture types) revealed a HR of 1.88 (95% CI: 1.17–3.00). Conclusions In conclusion, our results indicate that a daily intake of 330 mg of caffeine, equivalent to 4 cups (600 ml) of coffee, or more may be associated with a modestly increased risk of osteoporotic fractures, especially in women with a low intake of calcium.     

Fruit and Vegetable Intake and Hip Fracture Incidence in Older Men and Women: The CHANCES Project

The role of fruit and vegetable intake in relation to fracture prevention during adulthood and beyond is not adequately understood. We investigated the potential association between fruit and vegetable intake and hip fracture incidence in a large sample of older adults from Europe and the United States. A total of 142,018 individuals (116,509 women) aged ≥60 years, from five cohorts, were followed up prospectively for 1,911,482 person‐years, accumulating 5552 hip fractures. Fruit and vegetable intake was assessed by validated, cohort‐specific, food‐frequency questionnaires (FFQ). Ηip fractures were ascertained through national patient registers or telephone interviews/questionnaires. Adjusted hazard ratios (HRs) derived by Cox proportional hazards regression were estimated for each cohort and subsequently pooled using random effects meta‐analysis. Intake of ≤1 serving/day of fruit and vegetables combined was associated with 39% higher hip fracture risk (pooled adjusted HR, 1.39; 95% confidence interval [CI], 1.20 to 1.58) in comparison with moderate intake (>3 and ≤5 servings/day) (p_{for heterogeneity} = 0.505), whereas higher intakes (>5 servings/day) were not associated with lower risk in comparison with the same reference. Associations were more evident among women. We concluded that a daily intake of 1 or <1 servings of fruits and vegetables was associated with increased hip fracture risk in relation to moderate daily intakes. Older adults with such low fruit and vegetable consumption may benefit from raising their intakes to moderate amounts in order to reduce their hip fracture risk. © 2016 American Society for Bone and Mineral Research.     

Validation of a short questionnaire for estimating dietary calcium intakes

Summary

Concern about calcium supplements, and mainly minor side effects (e.g. constipation) impacting on compliance, means that assessing dietary calcium intake is important. There is no suitable biomarker. Compared to food diaries, a short questionnaire was an efficient way of confirming that patients had adequate calcium intakes (>700 or >1,000 mg)

Introduction

Calcium is usually given alongside treatments for osteoporosis, but recent concerns about potential side effects have led to questioning whether supplements are always necessary. It is difficult to assess calcium intake in a clinical setting and be certain that the patient is getting enough calcium. The aim of this study was to determine whether a short questionnaire for estimating dietary calcium intakes in a clinical setting was fit for purpose.

Methods

We assessed dietary calcium intakes using a short questionnaire (CaQ) in patients attending an osteoporosis clinic (n?=?117) and compared them with calcium intakes obtained from a 7-day food diary (n?=?72) and a food frequency questionnaire (FFQ) (n?=?33).

Results

Mean (SD) daily calcium intakes from the CaQ were 836 (348)?mg; from the diaries, 949 (384)?mg; and from the FFQ, 1,141 (387)?mg. The positive predictive value (PPV) was >80 % for calcium cut-offs?>?700 mg and 70 % for cut-offs?>?1,000 mg. The calcium intakes for the false positives results were not far below the cut-off. For 1,200 mg, the PPV was 67 % or less.

Conclusion

The CaQ is an adequate tool for assessing whether a patient has daily calcium intakes above 700 or 1,000 mg; if below these cut-offs, it is possible that the patient still has enough calcium in the diet, which could be clarified by questioning the patient further. As there were few patients with calcium intakes above 1,200 mg a day, the CaQ cannot be recommended as a tool for confirming higher dietary calcium intakes.     

Soy protein consumption and bone mass in early postmenopausal Chinese women

Recent interest has been shown in the potential beneficial effects of phytoestrogens on bone health. As the early years of menopause are a period of rapid bone loss, and the risk for osteoporosis increases substantially, the habitual intake of soy protein and isoflavones may play a role in the retardation of bone loss. This paper reports the results of the baseline cross-sectional analysis of the association between dietary soy protein intake and bone mineral density/content in a population-based study of Chinese women. The sample comprised 454 healthy Chinese women (mean age 55.1±3.57) within the first 12 years of postmenopause. We estimated the dietary intake of soy protein and isoflavones, and other key nutrients, including dietary protein and calcium, using the quantitative food frequency method. Bone mineral density (BMD) and content (BMC) at the spine, hip and total body were measured with a dual energy X-ray densitometer (Hologic 4500A). Soy protein consumption was categorized as quartiles of intake, and related to BMD values at the spine and hip, and BMC of total body. Stratified analyses were carried out among women within or at least 4 years postmenopausal. We observed few differences in BMD/BMC values among the intake quartiles in women within the first 4 years of menopause. However, among the later postmenopausal women, we noted a dose-response relationship with increasing higher BMD values at the trochanter, intertrochanter as well as the total hip and total body with increasing soy protein intake quartiles (P<0.05 from tests for trend). The BMD values differed by about 4–8% between the first and fourth soy protein intake quartiles. Though women from the fourth intake quartile had a 2.9% higher BMD value compared with those from the first intake quartile, the difference was not statistically significant. Stepwise multiple linear regression analyses showed the association between soy intake quartiles and hip BMD as well as total body BMC values remained after adjusting for body weight, which was retained in the final model. Analyses based on soy isoflavones content yielded similar results. This study demonstrated that, among women after the initial few years postmenopausal, soy protein/isoflavones intake had a modest but significant association with hip BMD as well as total body BMC. The effects of soy protein and soy isoflavones on bone health should be further explored in populations with habitual dietary soy intake.     

Dietary calcium and hip fracture risk: The NHANES I Epidemiologic Follow-Up Study

The effect of dietary calcium on hip fracture risk was examined prospectively using the NHANES I Epidemiologic Follow-Up Study cohort, which is derived from a nationally representative sample of the United States population. A cohort of 4342 white men and postmenopausal women ages 50–74 years at baseline (1971–1975) were observed through 1987 for up to 16 years of follow-up. Quantitative estimates of calcium intake were obtained at baseline from a 24-h recall, while weekly frequency of dairy food consumption was obtained from a qualitative food frequency. By 1987, 44 men and 122 women had experienced a hip fracture according to hospital records or death certificates. In the total sample of women the risk of hip fracture was only slightly lower for the highest quartile compared with the lowest. However, although not statistically significant, the age-adjusted risk of hip fracture was approximately 50% lower in the highest quartile of calcium intake compared with the lowest quartile in the subgroup of women who were at least 6 years postmenopausal and not taking postmenopausal hormone. The low relative risk observed among men, although interesting, must be interpreted cautiously due to small sample size. Adjusting for other risk factors did not appreciably change the results for either sex. The pattern of relative risks for calcium quartiles and by selected cutpoints was not consistent with a dose-response effect of calcium. Our results suggest that calcium may lower hip fracture risk in late menopausal women.     

Prevalence of vitamin D insufficiency in postmenopausal south Indian women

Aim: To evaluate the dietary calcium and vitamin D status in south Indian postmenopausal women. Methods: Postmenopausal women (n=164) were evaluated for their daily dietary calcium intake, phytate to calcium ratio, and bone mineral parameters. Their serum leutinizing hormone (LH), follicle-stimulating hormone (FSH), 25-hydroxyvitamin D (25[OH]D), and parathyroid hormone levels (PTH) were measured. Results: Their age and BMI were 59.5 ± 8 years and 27 ± 5 kg/m², respectively. Their daily dietary intake of calcium was 323 ± 66 mg/day; phytate to calcium ratio, 0.56±0.1; LH, 26 ± 13.5 µIU/l; and FSH, 62.6 ± 30 µIU/l. Their dietary intake of calcium was low compared with the recommended daily/dietary allowance (RDA) of the Indian Council of Medical Research (ICMR) for the Indian population. Of the 164 patients studied, based on population-based reference values, 126 (77%) had normal 25(OH)D levels (9–37.6 ng/ml), and 38 (23%) had 25(OH)D deficiency. Using functional health-based reference values, 30 (18%) patients had normal 25(OH)D levels (>20 ng/ml), 85 (52%) had 25(OH)D insufficiency (10–20 ng/ml), and 49(30%) had 25(OH)D deficiency (<10 ng/ml). PTH and serum alkaline phosphatase (SAP) was significantly high in patients with 25(OH)D deficiency (p<0.05) compared with those with normal 25(OH)D levels. There was a negative correlation between 25(OH)D and PTH (r=–0.2; p<0.007) and SAP (r=–0.2; p<0.001). Dietary calcium correlated positively with dietary phosphates (r=0.8; p<0.001) and phytate to calcium ratio (r=0.75; p<0.001). Conclusions: Population-based reference values underdiagnosed vitamin D insufficiency and overdiagnosed normal vitamin D status. The diet was insufficient in calcium and high in phytate. About 82% of the study group had varying degrees of low 25-hydroxyvitamin D levels. The quality of diet has to be improved with enrichment/supplementation of calcium and vitamin D to suppress secondary hyperparathyroidism-induced bone loss and risk of fractures.     

Higher Dietary Calcium Intakes Are Associated With Reduced Risks of Fractures,Cardiovascular Events,and Mortality: A Prospective Cohort Study of Older Men and Women

The aim of this population‐based, prospective cohort study was to investigate long‐term associations between dietary calcium intake and fractures, non‐fatal cardiovascular disease (CVD), and death from all causes. Participants were from the Melbourne Collaborative Cohort Study, which was established in 1990 to 1994. A total of 41,514 men and women (～99% aged 40 to 69 years at baseline) were followed up for a mean (SD) of 12 (1.5) years. Primary outcome measures were time to death from all causes (n = 2855), CVD‐related deaths (n = 557), cerebrovascular disease‐related deaths (n = 139), incident non‐fatal CVD (n = 1827), incident stroke events (n = 537), and incident fractures (n = 788). A total of 12,097 participants (aged ≥50 years) were eligible for fracture analysis and 34,468 for non‐fatal CVD and mortality analyses. Mortality was ascertained by record linkage to registries. Fractures and CVD were ascertained from interview ～13 years after baseline. Quartiles of baseline energy‐adjusted calcium intake from food were estimated using a food‐frequency questionnaire. Hazard ratios (HR) and odds ratios (OR) were calculated for quartiles of dietary calcium intake. Highest and lowest quartiles of energy‐adjusted dietary calcium intakes represented unadjusted means (SD) of 1348 (316) mg/d and 473 (91) mg/d, respectively. Overall, there were 788 (10.3%) incident fractures, 1827 (9.0%) incident CVD, and 2855 people (8.6%) died. Comparing the highest with the lowest quartile of calcium intake, for all‐cause mortality, the HR was 0.86 (95% confidence interval [CI] 0.76–0.98, p_trend = 0.01); for non‐fatal CVD and stroke, the OR was 0.84 (95% CI 0.70–0.99, p_trend = 0.04) and 0.69 (95% CI 0.51–0.93, p_trend = 0.02), respectively; and the OR for fracture was 0.70 (95% CI 0.54–0.92, p_trend = 0.004). In summary, for older men and women, calcium intakes of up to 1348 (316) mg/d from food were associated with decreased risks for fracture, non‐fatal CVD, stroke, and all‐cause mortality. © 2015 American Society for Bone and Mineral Research.     

Determinants of bone mass in Chinese women aged 21–40 years. II. Pattern of dietary calcium intake and association with bone mineral density

A study on the determinants of bone mass in young women is being carried out among 287 young Chinese women aged 21–40 years. The baseline cross-sectional data show that the mean dietary calcium intake, estimated from the quantitative food frequency method, was 448 mg/day (standard deviation = 219). About 50% of the calcium source was from vegetables and 22% from dairy products. Among women aged 21–30 years, those with a dietary calcium intake of at least 600 mg/day had a 4%–7% higher mean bone mineral density at the spine and femur when compared with those with a mean intake below 300 mg/day. In women aged 31–40 years, subjects belonging to the highest quartile of calcium density (35 mg/420 kJ) had a 3%–8% higher mean bone mineral density at the spine and femur when compared with those in the lowest quartile (<20.8 mg/420 kJ). Favorable calcium intake is beneficial in this population of young women with habitual low dietary calcium intake.     

Calcium Bioavailability and Parathyroid Hormone Acute Changes after Oral Intake of Dairy and Nondairy Products in Healthy Volunteers

This study was designed to compare calcium bioavailability and serum parathyroid hormone acute changes after oral intake of 500 mg of elemental calcium from liquid milk, yogurt, calcium-citrate-enriched powdered milk or a calcium carbonate pill; or after intake of soybean imitation-milk. After a 12-h fast, blood samples were drawn both at baseline and 1, 2, 3 and 4 h after an oral intake of the above-mentioned products, which were ingested together with a light neutral breakfast. The administration order of the study products was randomly assigned to each of 19 healthy young volunteers (11 females, 8 males). The baseline serum concentrations of ionized calcium, phosphorus and intact parathyroid hormone (iPTH) were normal. Calcium-citrate-enriched powdered milk induced a significant increase in serum ionized calcium (p<0.001) and a significant and continuous decrease in serum iPTH concentration (p<0.001). Yogurt and the calcium carbonate pill induced a similar but less significant effect, increasing serum ionized calcium (p<0.05) and decreasing serum iPTH (p<0.01). Liquid milk only induced a significant change in serum ionized calcium and iPTH concentration during the first 2 h; this effect was lost during the following 2 h. In conclusion, our study suggests the possibility that the addition of calcium citrate to powered milk may improve calcium bioavailability and enhance the inhibitory effect on serum iPTH in the assayed conditions. Received: 15 September 1998 / Accepted: 15 January 1999     

A prospective study of the effects of 1-year calcium-fortified soy milk supplementation on dietary calcium intake and bone health in Chinese adolescent girls aged 14 to 16

The Chinese diet is low in calcium, including among adolescent girls, with an average intake around 500 mg per day. In this study, we compared the percentage change in bone mineral density and content of the spine and hip region in a 1-year follow-up study between 104 adolescent girls aged 14 to 16 years receiving 375 ml calcium-fortified soymilk supplementation and 95 girls in the control group. The mean percentage changes of bone mineral density/content (BMD/BMC) and standard deviation (SD) at 1 year for the supplementation and control groups were as follows: neck of the femur BMD 2.7±2.94%, 1.8±3.49% (P =0.08); trochanter BMD 3.3±3.27%, 1.6±2.94% (P <0.001); intertrochanter BMD 3.6±3.05%, 2.32±2.95% (P =0.002); total hip BMD 3.1±2.39%, 2.05±2.22% (P =0.001); total hip BMC 3.8±3.05%, 2.6±2.96% (P =0.006). The percent difference between the percentage of bone changes in the supplementation and control groups [100× (soymilk-control)/control] ranged from 45 to 113%. We observed no differences in the spine BMD/C and no differences in changes of height and weight between the soymilk supplementation and control groups, which yielded similar results. Stepwise multivariate regression analysis including height, weight, growth stage, dietary energy, protein, calcium from usual diet and physical activity also showed that supplementation was significantly associated with a percentage increase in BMD/C at the hip. We conclude that 375 ml calcium-fortified soymilk supplementation, or an equivalent of about two glasses, is among the effective strategies for bone acquisition and the optimization of peak bone mass in adolescent girls.     

A 4-year follow-up study of the effects of calcium supplementation on bone density in elderly postmenopausal women

To determine the long-term effect of calcium supplementation on bone density, 84 elderly women (54–74 years) more than 10 years past the menopause were studied for 4 years as part of a follow-up study of a randomized, double-masked, placebo-controlled trial. The placebo group who did not take calcium supplements at all during the 4-year study (control group,n=21) served as a comparison with the treated group who took calcium supplements for 4 years (calcium supplement group,n=14). We also studied subjects who were treated for 2 years with calcium supplements and then ceased taking them (non-compliant group,n=49). The changes in bone density at the lumbar spine, hip and ankle sites, current calcium intake and activity were monitored. Over the 4 years the calcium supplement group (mean calcium intake 1988±90 mg/day) did not lose bone at the hip and ankle site. The control group (mean calcium intake 952±109 mg/day) lost significantly more bone than the calcium supplement group at all sites of the hip and ankle. No overall bone loss was seen at the spine, in either group, over the 4 years of this study. Between years 2 and 4 the non-compliant group (mean calcium intake 981±75 mg/day) lost significantly more bone at all sites of the ankle than the calcium supplement group. Therefore, calcium supplementation produces a sustained reduction in the rate of loss of bone density at the ankle and hip sites in elderly postmenopausal women. Increasing dietary calcium intake in women should be the aim of a public health campaign.     

Exercise frequency and calcium intake predict 4-year bone changes in postmenopausal women

The aim of this study was to examine the association of exercise frequency and calcium intake (CI) with change in regional and total bone mineral density (BMD) in a group of postmenopausal women completing 4 years of progressive strength training. One hundred sixty-seven calcium-supplemented (800 mg/day) sedentary women (56.1±4.5 years) randomized to a progressive strength training exercise program or to control were followed for 4 years. Fifty-four percent of the women were using hormone therapy (HT) at baseline. At 1 year, controls were permitted to begin the exercise program (crossovers). The final sample included 23 controls, 55 crossovers, and 89 randomized exercisers. Exercisers were instructed to complete two sets of six to eight repetitions of exercises at 70–80% of one repetition maximum, three times weekly. BMD was measured at baseline and thereafter annually using dual-energy X-ray absorptiometry. Four-year percentage exercise frequency (ExFreq) averaged 26.8%±20.1% for crossovers (including the first year at 0%), and 50.4%±26.7% for exercisers. Four-year total CI averaged 1,635±367 mg/day and supplemental calcium intake, 711±174 mg/day. In adjusted multiple linear regression models, ExFreq was positively and significantly related to changes in femur trochanter (FT) and neck (FN), lumbar spine (LS), and total body (TB) BMD. Among HT users, FT BMD increased 1.5%, and FN and LS BMD, 1.2% ( p <0.01) for each standard deviation (SD) of percentage ExFreq (29.5% or 0.9 days/week). HT non-users gained 1.9% and 2.3% BMD at FT and FN, respectively, ( p <0.05) for every SD of CI. The significant, positive, association between BMD change and ExFreq supports the long-term usefulness of strength training exercise for the prevention of osteoporosis in postmenopausal women, especially HT users. The positive relationship of CI to change in BMD among postmenopausal women not using HT has clinical implications in light of recent evidence of an increased health risk associated with HT.     

Validation of a Food-Frequency Questionnaire for the Assessment of Calcium Intake in Schoolchildren Aged 9–10 Years

Bone mass increases steadily until age 20–30 years, when peak bone mass (PBM) is acquired. Nutrition plays a critical role in achievement of the optimal genetically programmed PBM, with reduction in the risk of osteoporosis later in life. Intake of nutrients can be estimated through the use of various tools; typically, food-frequency questionnaires (FFQs) are used in epidemiologic studies. The aim of this study was to validate a 21-item, semiquantitative FFQ to assess important nutrient intakes for bone health in Italian schoolchildren 9–10 years of age. Relative validation was accomplished through comparison of the 7-days weighed food record (7D records) with an FFQ developed ad hoc, completed by a group of 75 Italian schoolchildren (36 females, 39 males). Agreement between the two methods was evaluated by Spearman’s correlation test and Bland–Altman analysis applied on the data on intake of energy, macronutrients, and micronutrients. Particular attention was devoted to nutrients relevant for bone health. Good correlations between the two methods (FFQ and 7D records) were observed for all nutrients. In particular, mean dietary calcium intakes were 725.6 mg/day (95 % CI 683.2–768.1) from 7D records and 892.4 mg/day (95 % CI 844.6–940.2) from the FFQ. These results indicate that our FFQ for schoolchildren aged 9–10 years is highly acceptable as it is an accurate method that can be used in large-scale or epidemiological studies for the evaluation of nutrient intakes important for the prevention of osteoporosis in a similar population.