In older people, higher dietary calcium intake may lower the risk of cardiovascular disease, but not of stroke and fracture, new research from South Korea suggests. The results were presented at ENDO 2016, the annual meeting of the Endocrine Society, in Boston.
"The role of dietary calcium intake in cardiovascular disease, stroke and fracture is controversial. Moreover, participants in previous studies were from populations that had calcium-rich diets. We aimed to evaluate whether high dietary calcium intake increases the risk of CVD, stroke and fracture in a population with low calcium intake," said lead author Dr Sung Hye Kong, resident physician in the department of internal medicine of Seoul National University Hospital in Seoul, South Korea.
Kong and colleagues conducted their research among individuals in Korea's ongoing prospective community-based Ansung and Ansan Cohort Study that began in 2001. Of the 4,589 men and 5,042 women in the cohort study's database who were 40 years of age and above at baseline and were followed up for an average of 13 years, the authors performed their analyses in 2,199 men and 2,704 women over 50 years of age without previous cardiovascular disease and stroke.
The individuals in the study reported their dietary food intake in periodic food frequency questionnaires. Cardiovascular disease, stroke and fractures were recorded during interviews and examinations every two years. In their statistical analyses, the authors made adjustments for age, body mass index, vegetable and fruit intake, protein and sodium intake, physical activity, smoking and drinking, history of hypertension and diabetes, total energy from the diet, and additionally adjusted for menopausal status and hormone replacement therapy in women.
In older women in this population with low dietary calcium intake, higher dietary calcium intake was significantly associated with decreased risk of cardiovascular disease, but not significantly associated with risk of stroke and fracture.
Objective: The role of dietary calcium intake in cardiovascular disease (CVD), stroke and fracture is controversial. Moreover, study subjects in previous studies were from high calcium intake populations. We aimed to evaluate whether high dietary calcium intake increases the risk of CVD, stroke, and fracture in a low calcium intake population.
Method: The present study was conducted in the Ansung and Ansan Cohort Study, the ongoing prospective community-based cohort study since 2001 in Korea. A total of 9,631 subjects (4,589 men and 5,042 women) aged over 40 years at baseline were followed up for a mean of 13 years. Of them, 2199 men over 50 years and 2704 postmenopausal women without previous CVD and stroke were included in the final analysis. Dietary food intake was assessed by repeated food frequency questionnaires. CVD, stroke and fracture events were ascertained from the interview in biennial examination. Hazard ratios (HR) with 95% confidence interval (CI) were estimated from cox regression analysis for CVD, stroke, and fracture after adjusting for age, body mass index, vegetable and fruit intake, protein and sodium intake, physical activity, drinking and smoking status, history of diabetes and hypertension, and total energy from the diet.
Result: Study subjects were classified into quartiles based on baseline energy-adjusted calcium intake (median, interquartile range): quartile 1 (234, 151 mg/d), quartile 2(310, 158 mg/d), quartile 3 (439, 158 mg/d), quartile 4 (742, 273 mg/d). The incidence of CVD, stroke, and fracture were 1,976 (40.3%), 1,854 (37.8%), 572 (11.7%). Comparing with the first quartile of energy-adjusted calcium intake, the HRs (95% CI) for CVD were 0.762 (0.670-0.866) for quartile 2, 0.656 (0.570-0.754) for quartile 3, 0.524 (0.441-0.624) for quartile 4, respectively. Similarly, high dietary calcium intake decreased the risk of stroke. The HRs (95% CI) compared with the first quartile were 0.762 (0.670-0.866) for quartile 2, 0.656 (0.570-0.754) for quartile 3, 0.524 (0.441-0.624) for quartile 4, respectively. Fracture risk was not reduced across the quartiles of dietary calcium intake. The HRs (95% CI) were 1.015 (0.797-1.291) for quartile 2, 0.966 (0.749-1.244) for quartile 3, 0.760 (0.553-1.044) for quartile 4 compared with the quartile 1.
Conclusion: In older men and postmenopausal women in a low dietary calcium intake population, higher dietary intake of calcium was associated with decreased risk of CVD and stroke. Risk of fracture was not significantly associated with dietary calcium intake.