Low calcium intake is associated with high plasma homocysteine levels in postmenopausal women

Nutritional interventions targeting homocysteine remain controversial, and further nutritional research is warranted. We thus sought to explore the determinants of plasma homocysteine other than B-group vitamins. This cross-sectional study surveyed the nutritional status of 713 Japanese postmenopausal women using a semiquantitative food frequency questionnaire. Associations between total energy, protein, fat, carbohydrate, and vitamin A and K intakes and homocysteine were insignificant. Mean homocysteine in the second (536.1 ± 34.7 mg/day) and third (712.9 ± 115.6 mg/day) tertiles of calcium intake were lower than in the first tertile (379.6 ± 76.6 mg/day) by −0.57 nmol/mL (95 % confidence interval, −1.10 to −0.04, p = 0.04) and −1.18 nmol/mL (−1.76 to −0.60, p < 0.01), respectively, after adjustment for lifestyle and clinical factors (trend p < 0.01). Mean homocysteine in those with dietary calcium intake above the median (>536 mg/day) were lower regardless of the folic acid concentration; the differences were −1.59 nmol/mL (−2.33 to −0.85, p = 0.02) and −0.75 nmol/mL (−1.37 to −0.12, p < 0.01) for the high (<7.8 ng/mL) and low folic acid groups, respectively. There was no significant association between calcium and folic acid (p = 0.08). In conclusion, further prospective research to confirm our findings is needed for the development of nutritional inventions targeting homocysteine.