A recent clinical investigation published in the American Association for Cancer Research has shed light on how compounds found in walnuts may aid in colon cancer prevention. The analysis emphasized the important role of gut microbiota in metabolite production and immune modulation.

Led by researchers at the University of Connecticut’s Center for Molecular Oncology, the study focused on the effect of walnut consumption on the production of urolithins. These are metabolites derived from plant polyphenols called ellagitannins, which are abundant in walnuts. Metabolites are formed by gut bacteria and appear to influence inflammatory processes linked to colon health and cancer risk.

Researchers analyzed data from 39 participants who consumed walnuts regularly. They measured urinary levels of nine different urolithin metabolites and correlated these with blood markers of inflammation, immune cell activity in colon polyps, and detailed dietary and microbiome data. The findings revealed a wide variation in the ability of individuals to produce urolithin A, one of the key metabolites associated with health benefits.

Participants with higher levels of urolithin A showed decreased levels of several inflammatory markers in the blood, such as C-peptide, soluble adhesion molecules, and growth factors, especially pronounced in obese individuals. 

Notably, higher urolithin A levels also correlated with increased peptide YY, a hormone involved in gut health and satiety, while levels of the inflammatory cytokine TNFα tended to decrease, as confirmed through laboratory experiments with stimulated immune cells.

Further analysis of colon tissue through spatial imaging identified changes in cell cluster patterns related to urolithin A presence, including reduced expression of markers associated with inflammation and immune response.

These findings suggest that the capacity to produce urolithin A from walnuts may be linked to reduced inflammation and potentially lower cancer risk in the colon. The study supports the idea of personalized nutrition strategies that consider gut microbiomes, highlighting walnuts as a beneficial dietary component for colonic health.

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