An Exploratory Randomized Clinical Trial to Assess the Effects of Vitamin D and Leucine-Enriched Whey Protein Supplementation on Inflammaging and Gut Eubacterial Biomass in Cardiac Rehabilitation Patients

Whey protein (WP) supplementation could affect low-grade inflammation (inflammaging) and gut microbiome dysbiosis, both of which play key roles in non-communicable diseases (NCDs). Twenty-seven cardiac rehabilitation patients were randomly allocated to two groups: the case group (CA) (n = 14) received 80 g/die vitamin D and leucine-enriched WP supplement, combined with a standard hospital diet, while the control group (CO, n = 13) received the standard hospital diet alone. Blood and stool samples were collected at baseline (T0) and after two weeks (T1). At T1, serum levels of interleukin 6 (IL-6) and C-reactive protein (CRP) significantly decreased in the CA group. Ferritin levels significantly decreased within both groups and between the two groups. No significant differences were observed for IL-1β, tumor necrosis factor-α (TNF-α), or IL-10. A clear difference in the bacterial intestinal microbiome composition between the case group at T1 (CAT1) and at T0 (CAT0), and control group at T0 (COT0) and at T1 (COT1), was observed. The eubacterial rpoB copy number, which was quantified by qPCR, significantly increased between CAT0 and CAT1, in contrast to the Lactobacillus spp. rpoB copy number. Our exploratory results showed that vitamin D and leucine-enriched WP supplementation could have a potential effect on chronic inflammation and gut microbiota composition in cardiac rehabilitation patients.