Positive relation between dietary inflammatory index and osteoporosis in postmenopausal women

Background: Previous studies have shown that some dietary components may be implicated in the aetiology of postmenopausal osteoporosis. Objective: We examined the relationship between Dietary Inflammatory Index (DII^®) and osteoporosis in postmenopausal women. Study design: Eight hundred and fifty postmenopausal women aged 50-65 years were randomly selected from 87 health care centers. Bone mineral density (BMD) was measured using the anterior-posterior lumbar spine (L1-L4) and proximal femur neck through Hologic QDR 4500W (S/N 50266) dual-energy X-ray absorptiometry device. After checking inclusion and exclusion criteria and diagnosis of osteoporosis, 124 women with normal bone mineral density (normal-BMD) and 108 women with osteoporosis were selected. Demographic, anthropometric, physical activity, midwifery, and dietary intake questionnaires were completed. DII was calculated based on a valid and reliable 168-item semi-quantitative food frequency questionnaire using 37 (out of 45) food parameters. A Logistic regression model adjusted for confounders was applied to estimate osteoporosis's odds ratio (OR) based on modeling DII as a continuous and dichotomous variable. Results: In this study, DII scores ranged from -3.71 (the most anti-inflammatory score) to +4.16 (the most pro-inflammatory score). The median DII value among the osteoporosis group was 0.97, among the normal group it was -0.31, indicating a more pro-inflammatory diet for osteoporosis. There were positive associations between osteoporosis and DII based on both continuous (Adjusted OR=3.467, 95% confidence interval (CI): 2.280-5.272, P-value<0.001) and dichotomous (Adjusted OR: DII ≤-0.31 / >-0.31=0.248, 95% CI: 0.110-0.561, P-value=0.001) measures in modeling adjusted for age, BMI, post-menopausal years, parity, education, total energy intake, and physical activity. Conclusions: These data suggest a pro-inflammatory diet, as indicated by increasing the DII score, may be a risk factor for osteoporosis in postmenopausal Iranian women.