1 Sao Paulo University, Sao Paulo, Brasil. Food and Nutrition Research Center (NAPAN), Sao Paulo, Brasil; 2 Federal University of Sao Paulo, Sao Paulo, Brasil.
Objectives: Considering that experimental and epidemiological studies have shown that both magnesium deficiency and excess have deleterious effects on bone, the aim of this study was to investigate the relationship between magnesium intake and bone mass density (BMD) in postmenopausal women. Methods: Was conducted a cross-sectional study with 150 women, mean age 68.7 (9.1) years old. BMD were obtained using dual-energy X-ray absorptiometry (DXA), and 3-day food diary were used to assess magnesium intake, it were coded and analyzed, using the Nutrition Data System for Research softwar). The prevalence of low and adequate magnesium intake was estimated using the Estimated Average Requirements (EAR) method to define cut-off points, and the excess magnesium intake was estimated using Tolerable Upper Intake Levels (UL) recommendation. The results were expressed as mean (SD). Results: 26.7% of the sample presented normal bone density, 40,7% low bone density (osteopenia), and 32.7% osteoporosis. The mean magnesium intake was 254.6 mg/day. Only 28% of subjects presented adequate magnesium intake, 62.3% presented low magnesium intake and 9.3% presented excess magnesium intake. The lumbar spine BMD was higher in women with excessive magnesium than those who presented adequate magnesium intake (0.7950g/m2 vs. 0.7098g/m2; p=0.016). Was observed a positive correlation between magnesium intake and total body BMD (r=0.326; p=0.040) only in women with normal bone density. Conclusions: The mean intake of magnesium for the majority of sample was next EAR, and among those who have ingested excess amounts of magnesium the mean intake was next UL. Greater magnesium intake showed a positive effect on the lumbar spine BMD of the whole sample and on the total BMD in women with normal bone density. Thus, we can conclude that a higher magnesium intake can help in both treatment and prevention of osteoporosis in postmenopausal women.