Habitual dietary calcium intake and blood pressure change around the menopause: a longitudinal study

In a 10-year follow-up study, blood pressure and dietary intake were measured annually in 167 healthy perimenopausal normotensive women. Their initial ages ranged between 49 and 56 years and habitual calcium intake between 560 and 2580 mg/day (mean 1110 mg/day); they lived in the mixed rural/industrial community of Ede, the Netherlands. The longitudinal design provided an opportunity to study the 'natural history' of blood pressure and the effect of dietary calcium during and after the period of ovarian failure. For data analysis, person-time experience was divided into three menopausal periods. Based on years relative to menopause three menopausal cohorts were created starting 2 years before, 2 years after and 6 years after menopause, each was followed for 4 years. Changes in systolic (SBP) and diastolic blood pressure (DBP) during the menopausal periods were adjusted for change in body mass index and other relevant variables in multiple regression analysis. An average decline in SBP of 6 mm Hg was observed in the period of 2 years before menopause to 6 years after menopause, and an increase of almost 5 mm Hg in the period between 6 and 10 years after menopause. A significant change in DBP was not observed. Neither changes in, nor the absolute level of, calcium intake showed any relevant association with blood pressure change. Ovarian failure seems to reverse temporarily the increase in blood pressure due to aging. The results do not suggest that a habitual calcium intake exceeding 800-1000 mg/day (the current Recommended Daily Allowance for adults) is effective in preventing hypertension during the peri- and postmenopausal period.