Dietary Supplements

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.

Gheri C, Luisi M, et al. • Biomolecules • 2026

PubMed 42939738 DOI 10.3390/biom16101484
TL;DR

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.

Key Findings

Results

Two weeks of vitamin D and leucine-enriched whey protein supplementation was associated with significantly decreased serum IL-6 and CRP in the case group.

  • 27 cardiac rehabilitation patients were randomized: case group (CA, n = 14) received 80 g/day vitamin D and leucine-enriched WP plus standard hospital diet; control group (CO, n = 13) received standard hospital diet alone.
  • Blood samples were collected at baseline (T0) and after two weeks (T1).
  • At T1, serum IL-6 and CRP "significantly decreased in the CA group."
Results

Ferritin levels significantly decreased within both groups and between the two groups.

  • Ferritin decreased in both the CA and CO groups from T0 to T1.
  • A significant between-group difference in ferritin was also reported.
Results

No significant differences were observed for IL-1β, TNF-α, or IL-10.

  • These cytokines were measured at T0 and T1 in both groups.
  • Only IL-6 and CRP changed significantly in the CA group.
Results

Gut bacterial community composition differed clearly between T0 and T1 in both the case and control groups.

  • A clear difference was observed between CAT1 and CAT0, and between COT0 and COT1.
  • Stool samples were collected at T0 and T1.
Results

Eubacterial rpoB copy number, quantified by qPCR, significantly increased in the case group between T0 and T1, in contrast to Lactobacillus spp. rpoB copy number.

  • The increase in total eubacterial biomass was observed between CAT0 and CAT1.
  • Lactobacillus spp. rpoB copy number did not show the same increase (reported as being in contrast).
Conclusions

The authors conclude that the supplement could have a potential effect on chronic inflammation and gut microbiota composition, but the study is exploratory.

  • The trial was described as exploratory with a small sample (n = 27).
  • The intervention lasted two weeks in cardiac rehabilitation inpatients.

What This Means

This small exploratory trial looked at whether a supplement containing whey protein enriched with leucine and vitamin D (80 g per day) could affect low-grade chronic inflammation and gut bacteria in people undergoing cardiac rehabilitation. Twenty-seven patients were randomly assigned to receive the supplement plus the standard hospital diet, or the standard hospital diet alone, for two weeks. In the supplement group, blood levels of two inflammation markers, IL-6 and CRP, fell significantly. Ferritin fell in both groups, with a significant difference between them. Other inflammatory markers (IL-1β, TNF-α, IL-10) did not change significantly. Gut bacterial composition changed in both groups, and the total amount of gut bacteria (measured by eubacterial rpoB gene copies) rose in the supplement group, while Lactobacillus did not show the same increase. This research suggests that the supplement may influence inflammation and gut bacteria in cardiac rehabilitation patients. However, the study was small, short, and exploratory, so the results need confirmation in larger and longer trials before any firm conclusions can be drawn.

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Citation

Gheri C, Luisi M, Lucarini L, Biffi B, Madiai S, Roccotelli A, et al.. (2026). 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.. Biomolecules. https://doi.org/10.3390/biom16101484