Interactions Between Dietary Calcium Intake and Bone Mineral Density or Bone Geometry in a Low Calcium Intake Population (KNHANES IV 2008-2010)

Context: Little is known about the interactions between dietary calcium intake and bone strength parameters in populations or areas with low calcium intake. Objective: The objective of the study was to investigate the relationship between dietary calcium intake and bone mineral density (BMD) or bone geometry in an Asian population with low calcium intake. Design and Setting: This was a cross-sectional study of data from the Korea National Health and Nutrition Examination Survey, 2008-2010. Participants: A total of 3448 men and 3812 women older than 50 years were stratified by daily dietary calcium intake: less than 400 mg/d, 400-799 mg/d, 800-1199 mg/d, and 1200 mg/d or greater. Main Outcome Measures: BMD was measured by dual-energy X-ray absorptiometry and the geometric index was calculated. Results: Mean daily calcium intake was 470 mg/d in this population. BMD in the lumbar spine (both sexes) and femoral neck (women) was significantly lower only when calcium intake was less than 400 mg/d. In men, femoral neck and total hip BMD was positively related to calcium intake up to 1200 mg/d. Calcium intake less than 400 mg/d was negatively related to femoral cortical thickness and buckling ratio. These interactions disappeared when the 25-hydroxyvitamin D level was 30 ng/mL or greater in men and 20 ng/mL or greater in women. Conclusions: Low calcium intake was significantly related with low BMD and increased risk of osteoporosis. However, the association between calcium and BMD was not consistently linear, and a sufficient vitamin D level appears to compensate for the negative influences of low calcium intake on bone.