Dairy food consumption, blood pressure and retinal microcirculation in adolescents

Background and aims: The relationship between dairy food consumption and dietary calcium intake, and vascular risk factors during adolescence remains unclear. We aimed to prospectively assess whether dairy food consumption (milk, cheese, yoghurt) is associated with blood pressure (BP) and retinal microvascular signs among adolescents. Methods and results: As many as 2353 and 1216 participants aged 12 and 17, respectively, were examined. Longitudinal analyses involved 888 subjects with complete baseline and follow-up data. Dairy consumption was assessed from validated semi-quantitative food frequency questionnaires. BP information was collected and retinal vessel caliber was quantified from digital photographs using computer software. In girls, after multivariable adjustment, each serve/day increase in total dairy intake was concurrently associated with 1.04 (p=0.03) and 1.10mm Hg (p=0.02) decreases in mean diastolic and arterial BP, respectively. Also in girls, each serve/day increase in cheese intake over 5 years was concurrently related to 7.18 (p=0.001), 5.28 (p=0.002) and 5.79mm Hg (p=0.001) decrease in mean systolic, diastolic and arterial BP, respectively. Among girls, each 100mg/day increase in dietary calcium intake was associated with a concurrent 0.5 (p=0.01) and 0.3mm Hg (p=0.02) decrease in mean systolic and arterial BP, respectively. Cross-sectionally, adolescents in the highest versus lowest tertile of yoghurt intake had ~1.3μm wider retinal arterioles (p=0.05) and ~2.0μm narrower venules (p=0.04). Conclusions: Consumption of dairy products, particularly cheese, could have a beneficial effect on BP, particularly among girls.