Longer-Term Soy Nut Consumption Improves Vascular Function and Cardiometabolic Risk Markers in Older Adults: Results of a Randomized, Controlled Cross-Over Trial

Abstract

Abstract Objectives Soy foods may contribute to the beneficial effects of plant-based diets on cardiovascular disease (CVD) risk. However, their effects on vascular function have hardly been investigated. The objective was to investigate if longer-term soy nut consumption improves vascular function and cardiometabolic health in older adults. Methods Twenty-three apparently healthy participants (60–70 years; BMI between 20–30 kg/m2) participated in a randomized, controlled, single-blinded cross-over trial with an intervention (67 g of soy nuts daily providing 25.5 g soy protein) and control period (no nuts) of 16 weeks, separated by eight weeks wash-out. Volunteers followed the Dutch food-based dietary guidelines. At baseline and at 8 and 16 weeks anthropometric measurements and fasting blood samples were collected. Markers of vascular function (i.e., endothelial function, arterial stiffness, and microvascular structure) were assessed at week 16. Results No serious adverse events were reported and the soy nut regime was well tolerated. Body weight remained stable. Serum isoflavone concentrations, a marker of compliance, increased after the intervention period (daidzein: 128.3 ng/mL; 95% CI: 72.6–183.9 ng/mL; P < 0.001 and genistein: 439.8 ng/mL 95% CI: 246.7–632.9 ng/mL; P < 0.001). The brachial artery flow-mediated vasodilation (FMD) response increased by 1.49 pp (95% CI: 0.03–2.95 pp; P = 0.046) following the soy intervention, but no effect was found on the carotid artery reactivity (CAR) response. Arterial stiffness, assessed by carotid-to-femoral pulse wave velocity (PWVc-f), was unchanged. Retinal arteriolar calibers (CRAE), a measure for microvascular structure, tended to improve by 1.42 mm (95% CI: −0.05–2.90 mm; P = 0.059). Soy consumption also lowered serum LDL-cholesterol concentrations by 0.17 mmol/L (95% CI: 0.02–0.32 mmol/L; P = 0.027). HDL-cholesterol and triacylglycerol (TAG) did not change. Finally, office SBP and DBP decreased by 4 mmHg (95% CI: 0–8 mmHg; P = 0.034) and 2 mmHg (95% CI: 1–4 mmHg; P = 0.005), respectively. Conclusions A longer-term daily intake of soy nuts improved endothelial function, office blood pressure, and serum LDL-cholesterol concentrations, suggesting mechanisms by which an increased soy food intake beneficially affects CVD risk in older adults. Funding Sources This study was supported by a grant from the Alpro Foundation.