Effects of non-fat dairy products added to the routine diet on vascular function: a randomized controlled crossover trial

Background and aims: High consumption of low- and non-fat dairy products is associated with reduced risk of high blood pressure (BP) and central arterial stiffness. However, interventional studies to determine if the addition of non-fat dairy products to the diet is capable of reducing central BP and improving vascular function are lacking. The aim of this study was to determine if the solitary addition of non-fat dairy products to the normal routine diet would reduce central BP and improve vascular function in middle-aged and older adults with elevated BP.

Methods and results: Using a randomized, crossover intervention study design, forty-nine adults (44% men, 53 ± 2 years, 170 ± 2 cm, 88 ± 3 kg; mean ± SEM) with elevated BP (134 ± 1/81 ± 1 mm Hg) underwent a High Dairy condition (+4 servings/day of conventional non-fat dairy products) and No Dairy condition (+4 servings/day fruit products) in which all dairy products were removed. Both dietary conditions lasted 4 weeks with a 2-week washout before crossing over into the alternate condition. The High Dairy condition produced reductions in central systolic BP (-3 ± 1 mm Hg) and carotid-femoral pulse wave velocity (-0.5 ± 0.1 m/sec), with a concomitant increase in brachial flow-mediated dilation (+1.1 ± 0.4%) and cardiovagal baroreflex sensitivity (+5 ± 1 ms/mm Hg) (P < 0.05 for all vs. baseline). In the No Dairy condition, brachial flow-mediated dilation was reduced (-1.0 ± 0.1%, P < 0.05 vs. baseline).

Conclusions: The solitary manipulation of conventional dairy products in the normal routine diet modulates levels of central BP and vascular function in middle-aged and older adults with elevated BP.

Clinical trial registration: clinicaltrials.gov Identifier: NCT01577030.