Effects of dairy products on intracellular calcium and blood pressure in adults with essential hypertension

Background: Consumption of dairy foods has been associated with lower blood pressure in certain populations. Objective: This study examined the effects of dairy foods on blood pressure (BP) and intracellular calcium ((Ca)_i) and the dependence of BP changes on changes in (Ca)_i. Design: Twenty-three stage 1 hypertensive adults were fed the following 3 experimental diets (5 wk each) in a randomized cross-over design study; a dairy-rich, high fruits and vegetables diet (D-F&V; 30% fat, 7% saturated fat (SFA), 3.4 servings/d dairy), a high fruits and vegetables diet (F&V; 30% fat, 7% SFA, 0.4 servings/d dairy), and an average Western diet (control; 36% fat, 15% SFA, 0.4 servings/d dairy). Systolic (SBP) and diastolic (DBP) BP, calcium regulatory hormones, and erythrocyte (Ca)_i were determined. Results: SBP and DBP were significantly reduced by ∼2 mm Hg following both D-F&V and F&V diets vs. the control (P < 0.05). The D-F&V diet significantly lowered 1,25-dihydroxyvitaminD compared with the F&V and control diets (P < 0.01). Serum calcium, parathyroid hormone, calcitonin, and renin activity were unchanged. The D-F&V diet lowered (Ca)_i vs. the other two diets (P < 0.01), and this change correlated with the fall in DBP (r = 0.52, P < 0.05). Subjects who responded to the D-F&V diet by significantly reducing (Ca)_i exhibited significantly greater net decreases in DBP on the D-F&V vs. the F&V (−2.8 ± 1.0 mm Hg) and control diets (−5.4 ±1.0 mm Hg; diet × group interaction, P < 0.02). Conclusion: Consumption of dairy foods beneficially affects (Ca)_i, resulting in improved BP in a subgroup defined by (Ca)_i response.