Impact of quantity and source of dietary protein intake within a healthy dietary pattern on cardiovascular disease risk factors in Singapore older adults: A randomized controlled trial

Abstract

Background: Higher protein diet (HPD) is recommended for older adults to support their muscle mass maintenance but its cardiovascular protective effects in this population remain controversial, potentially due to differences in protein sources. Objective: To investigate the effects of HPD with different source within a healthy dietary pattern (HDP) on conventional cardiovascular disease (CVD) risk factors and vascular health-related outcomes in Singapore older adults. Methods: In this 16-week randomized controlled trial, 55 participants were assigned to one of three groups: following a HDP alone (Control, n = 19), following a HDP with supplementing above 15 g/day of either casein protein (HPD-CP, n = 18) or soy protein (HPD-SP, n = 18). Blood pressure, lipid-lipoprotein profiles and composite CVD risk indicators were evaluated at baseline and post-intervention. Parameters of vascular function (flow-mediated dilation) and vascular regeneration (endothelial progenitor cell percentage and blood outgrowth cell functions) were also assessed. Results: The Control group exhibited significant increases in triglycerides level (+0.33 ± 0.1 mmol/L) and composite CVD risks (atherogenic index: +0.31 ± 0.11; Framingham predicted long-term CVD risk: +0.8 ± 0.43 %). In contrast, both HPD groups showed maintenance in lipid-lipoprotein profile and CVD risk predictors, with further significant reduction in total cholesterol level in the HPD-SP group (-0.28 ± 0.12 mmol/L). All groups showed significant increases in CD34+ cell expression and particularly, the HPD-SP group demonstrated potential to enhance angiogenic capacity of blood outgrowth endothelial cells. However, no changes were observed in other vascular function and vascular regeneration parameters. Conclusions: Adherence to an HPD, particularly from soy protein, within HDP supports the maintenance of lipid-lipoprotein profile and CVD risk predictors among Singapore older adults. These findings highlight HPD as a potential dietary strategy to promote cardiovascular health when adhering HDP in older adults, however, the source of protein may influence its effectiveness.