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Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study.

Warensjö E, Byberg L, Melhus H, Gedeborg R, Mallmin H, Wolk A, Michaëlsson K - BMJ (2011)

Bottom Line: Secondary outcome was osteoporosis diagnosed by dual energy x ray absorptiometry in the subcohort.The highest quintile of calcium intake did not further reduce the risk of fractures of any type, or of osteoporosis, but was associated with a higher rate of hip fracture, hazard ratio 1.19 (1.06 to 1.32).Gradual increases in dietary calcium intake above the first quintile in our female population were not associated with further reductions in fracture risk or osteoporosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgical Sciences, Section of Orthopaedics, Uppsala University, Uppsala, Sweden. eva.warensjo@surgsci.uu.se

ABSTRACT

Objective: To investigate associations between long term dietary intake of calcium and risk of fracture of any type, hip fractures, and osteoporosis.

Design: A longitudinal and prospective cohort study, based on the Swedish Mammography Cohort, including a subcohort, the Swedish Mammography Cohort Clinical.

Setting: A population based cohort in Sweden established in 1987.

Participants: 61,433 women (born between 1914 and 1948) were followed up for 19 years. 5022 of these women participated in the subcohort.

Main outcome measures: Primary outcome measures were incident fractures of any type and hip fractures, which were identified from registry data. Secondary outcome was osteoporosis diagnosed by dual energy x ray absorptiometry in the subcohort. Diet was assessed by repeated food frequency questionnaires.

Results: During follow-up, 14,738 women (24%) experienced a first fracture of any type and among them 3871 (6%) a first hip fracture. Of the 5022 women in the subcohort, 1012 (20%) were measured as osteoporotic. The risk patterns with dietary calcium were non-linear. The crude rate of a first fracture of any type was 17.2/1000 person years at risk in the lowest quintile of calcium intake, and 14.0/1000 person years at risk in the third quintile, corresponding to a multivariable adjusted hazard ratio of 1.18 (95% confidence interval 1.12 to 1.25). The hazard ratio for a first hip fracture was 1.29 (1.17 to 1.43) and the odds ratio for osteoporosis was 1.47 (1.09 to 2.00). With a low vitamin D intake, the rate of fracture in the first calcium quintile was more pronounced. The highest quintile of calcium intake did not further reduce the risk of fractures of any type, or of osteoporosis, but was associated with a higher rate of hip fracture, hazard ratio 1.19 (1.06 to 1.32).

Conclusion: Gradual increases in dietary calcium intake above the first quintile in our female population were not associated with further reductions in fracture risk or osteoporosis.

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Related in: MedlinePlus

Fig 2/ Multivariable adjusted spline curve for relation between cumulative average intake of dietary calcium and time to first hip fracture. Multivariable adjusted hazard ratio indicated by solid line and 95% confidence interval by dashed lines. Models were adjusted for age, total energy, retinol, alcohol intake, vitamin D intake, BMI, height, iparity, educational level, physical activity level, smoking status, calcium supplementation, previous fractures, and Charlson’s comorbidity index. Asterisks on x axis correspond to first (387 mg) and 99th (1591 mg) percentile of the cumulative intake of calcium. Reference value for estimation set at 800 mg, which corresponds to Swedish recommended level of calcium intake for women older than 50 years3
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fig2: Fig 2/ Multivariable adjusted spline curve for relation between cumulative average intake of dietary calcium and time to first hip fracture. Multivariable adjusted hazard ratio indicated by solid line and 95% confidence interval by dashed lines. Models were adjusted for age, total energy, retinol, alcohol intake, vitamin D intake, BMI, height, iparity, educational level, physical activity level, smoking status, calcium supplementation, previous fractures, and Charlson’s comorbidity index. Asterisks on x axis correspond to first (387 mg) and 99th (1591 mg) percentile of the cumulative intake of calcium. Reference value for estimation set at 800 mg, which corresponds to Swedish recommended level of calcium intake for women older than 50 years3

Mentions: In the highest quintile of calcium intake, the rate of fracture of any type and the rate of osteoporosis were similar to those in the third quintile (table 2), whereas the hip fracture rate was raised in the highest quintile (hazard ratio 1.19, 95% confidence interval 1.06 to 1.32). The non-linear association between dietary calcium intake and first hip fracture rate is further illustrated by the spline curve in fig 2. Neither quintiles of total calcium intake (including supplements) nor the use of calibrated dietary calcium intake essentially changed the estimated hazard ratios for fracture, although the higher fracture rate at low intake levels became more pronounced (table 3). The results also remained essentially unchanged after exclusion of women with a previous fracture of any type before the hip fracture event after baseline, or when the analysis was restricted to specific age intervals (<70, 70-80, >80 years).


Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study.

Warensjö E, Byberg L, Melhus H, Gedeborg R, Mallmin H, Wolk A, Michaëlsson K - BMJ (2011)

Fig 2/ Multivariable adjusted spline curve for relation between cumulative average intake of dietary calcium and time to first hip fracture. Multivariable adjusted hazard ratio indicated by solid line and 95% confidence interval by dashed lines. Models were adjusted for age, total energy, retinol, alcohol intake, vitamin D intake, BMI, height, iparity, educational level, physical activity level, smoking status, calcium supplementation, previous fractures, and Charlson’s comorbidity index. Asterisks on x axis correspond to first (387 mg) and 99th (1591 mg) percentile of the cumulative intake of calcium. Reference value for estimation set at 800 mg, which corresponds to Swedish recommended level of calcium intake for women older than 50 years3
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3101331&req=5

fig2: Fig 2/ Multivariable adjusted spline curve for relation between cumulative average intake of dietary calcium and time to first hip fracture. Multivariable adjusted hazard ratio indicated by solid line and 95% confidence interval by dashed lines. Models were adjusted for age, total energy, retinol, alcohol intake, vitamin D intake, BMI, height, iparity, educational level, physical activity level, smoking status, calcium supplementation, previous fractures, and Charlson’s comorbidity index. Asterisks on x axis correspond to first (387 mg) and 99th (1591 mg) percentile of the cumulative intake of calcium. Reference value for estimation set at 800 mg, which corresponds to Swedish recommended level of calcium intake for women older than 50 years3
Mentions: In the highest quintile of calcium intake, the rate of fracture of any type and the rate of osteoporosis were similar to those in the third quintile (table 2), whereas the hip fracture rate was raised in the highest quintile (hazard ratio 1.19, 95% confidence interval 1.06 to 1.32). The non-linear association between dietary calcium intake and first hip fracture rate is further illustrated by the spline curve in fig 2. Neither quintiles of total calcium intake (including supplements) nor the use of calibrated dietary calcium intake essentially changed the estimated hazard ratios for fracture, although the higher fracture rate at low intake levels became more pronounced (table 3). The results also remained essentially unchanged after exclusion of women with a previous fracture of any type before the hip fracture event after baseline, or when the analysis was restricted to specific age intervals (<70, 70-80, >80 years).

Bottom Line: Secondary outcome was osteoporosis diagnosed by dual energy x ray absorptiometry in the subcohort.The highest quintile of calcium intake did not further reduce the risk of fractures of any type, or of osteoporosis, but was associated with a higher rate of hip fracture, hazard ratio 1.19 (1.06 to 1.32).Gradual increases in dietary calcium intake above the first quintile in our female population were not associated with further reductions in fracture risk or osteoporosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgical Sciences, Section of Orthopaedics, Uppsala University, Uppsala, Sweden. eva.warensjo@surgsci.uu.se

ABSTRACT

Objective: To investigate associations between long term dietary intake of calcium and risk of fracture of any type, hip fractures, and osteoporosis.

Design: A longitudinal and prospective cohort study, based on the Swedish Mammography Cohort, including a subcohort, the Swedish Mammography Cohort Clinical.

Setting: A population based cohort in Sweden established in 1987.

Participants: 61,433 women (born between 1914 and 1948) were followed up for 19 years. 5022 of these women participated in the subcohort.

Main outcome measures: Primary outcome measures were incident fractures of any type and hip fractures, which were identified from registry data. Secondary outcome was osteoporosis diagnosed by dual energy x ray absorptiometry in the subcohort. Diet was assessed by repeated food frequency questionnaires.

Results: During follow-up, 14,738 women (24%) experienced a first fracture of any type and among them 3871 (6%) a first hip fracture. Of the 5022 women in the subcohort, 1012 (20%) were measured as osteoporotic. The risk patterns with dietary calcium were non-linear. The crude rate of a first fracture of any type was 17.2/1000 person years at risk in the lowest quintile of calcium intake, and 14.0/1000 person years at risk in the third quintile, corresponding to a multivariable adjusted hazard ratio of 1.18 (95% confidence interval 1.12 to 1.25). The hazard ratio for a first hip fracture was 1.29 (1.17 to 1.43) and the odds ratio for osteoporosis was 1.47 (1.09 to 2.00). With a low vitamin D intake, the rate of fracture in the first calcium quintile was more pronounced. The highest quintile of calcium intake did not further reduce the risk of fractures of any type, or of osteoporosis, but was associated with a higher rate of hip fracture, hazard ratio 1.19 (1.06 to 1.32).

Conclusion: Gradual increases in dietary calcium intake above the first quintile in our female population were not associated with further reductions in fracture risk or osteoporosis.

Show MeSH
Related in: MedlinePlus