Fig. 2

Comparison of prevalence of osteoporosis among groups according to frequency of coffee intake. a The results of comparison of prevalence of osteoporosis among groups according to model 1 (frequency of coffee intake were categorized by group 1: seldom, group 2: once or twice per week and group 3: greater than or equal to once per 2 days). The prevalence of osteoporosis was 9.82, 3.57, and 2.0 % in the three groups, respectively. There were significant differences among the three groups (P = 0.023 and P value for trend = 0.020). b The results of comparison of prevalence of osteoporosis among groups according to model 2 (frequency of coffee intake were categorized by group 1: seldom, group 2: moderate). The prevalence of osteoporosis was 9.82 and 2.84 % in the two groups, respectively. There were significant differences between the two groups (P = 0.029 and P value for trend = 0.007)