Purpose: Previous studies have shown a potential inverse relationship between blood pressure and daily calcium intake. The aim of the study was to assess the independent contribution of dairy product and calcium intake to blood pressure variations at a population level.
Methods: A sample of 912 men aged 45-64 years was randomly selected from the general population, as part of the French MONICA cross-sectional survey on cardiovascular risk factors (1995-1996). Extensive questionnaires on risk factors were filled out and each participant completed a three-consecutive-day food record. Two blood pressure measurements were performed at rest. In statistical analyses subjects were grouped according to quintiles of dairy product or calcium intakes.
Results: Systolic and diastolic blood pressures significantly decreased from the lowest [145.4 (standard error (SE) 1.55) and 89.0 (SE 0.94) mmHg respectively] to the highest quintile [135.6 (SE 1.26) and 85.3 (SE 0.84) mmHg respectively] of dairy product intakes in bivariate analysis. After multivariate linear regression analysis adjusted for confounders [centre, age, daily sodium, magnesium, calcium and alcohol intake, daily energy intake without alcohol, dieting, physical activity, body mass index (BMI), smoking, and use of antihypertensive or lipid-lowering drugs], the difference in systolic blood pressure remained significant. Results were similar when calcium intake was considered. After adjustment for confounders, the association between calcium-dairy product combination and blood pressure was the most significant when intakes of dairy products and calcium were both higher than the median.
Conclusion: Dairy products and dietary calcium are both significantly and independently associated with low levels of systolic blood pressure.