Gut microbes may be the reason walnuts lower cardiovascular risk

New research could help identify foods with similar benefits.
Loukia Papadopoulos
Walnuts protect the heart.jpg
Walnuts protect the heart.


New research is examining the gene expression of gut microbes to better understand the heart-healthy benefits of walnuts. The study found that the nuts may be linked to beneficial changes in the mix of microbes found in our gut and could soon help identify other foods or supplements with similar benefits.

This is according to a press release by the American Society for Biochemistry and Molecular Biology published on Saturday.

 “Research has shown that walnuts may have heart-healthy benefits like lowering cholesterol levels and blood pressure,” said Mansi Chandra, an undergraduate researcher at Juniata College in Huntingdon, Pennsylvania. 

“This motivated us to look at how walnuts benefited the gut microbiome and whether those effects led to the potential beneficial effects. Our findings represent a new mechanism through which walnuts may lower cardiovascular disease risk.”

To come to their conclusions, the researchers used an approach known as metatranscriptomics, a recently developed technology that can be used to quantify gene expression. 

“To our knowledge, this is the first study to use metatranscriptomics analysis for studying the impact of walnut consumption on the gut microbiota gene expression,” Chandra said. “These exploratory analyses contribute to our understanding of walnut-related modulation of gut microbiome, which could be very impactful in learning how gut health impacts our heart health in general.”

The research consisted of a controlled-feeding study in which 35 participants with high cardiovascular risk were randomly assigned to one of three study diets. 

The diets included one that incorporated whole walnuts, one that included the same amount of omega-3 fatty acid alpha-linolenic acid, or ALA, and polyunsaturated fatty acids as the walnut diet but without walnuts, and one that partially substituted another fatty acid known as oleic acid for the same amount of ALA found in walnuts but without consumption of any walnuts.  

Analyzing gene expression

The researchers then used metatranscriptomics to analyze gene expression and the bacteria in the gastrointestinal tract from fecal samples.

Participants on the walnut diet were found to have higher levels of Gordonibacter bacteria in the gut, a bacterium that converts the plant polyphenols ellagitannins and ellagic acid into metabolites that allow them to be absorbed by the body. 

More studies still need to be undertaken to confirm these initial observations but the research could eventually help inform dietary interventions based on walnuts. “Since a lot of people are allergic to nuts, these findings also suggest that other food supplements that boost the endogenous production of homoarginine may also be helpful,” Chandra concluded in the press statement.


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