Nuts beneficial for lowering blood pressure and cholesterol levels
A new study examining the gene expression of gut microbes suggests that the heart-healthy benefits of nuts may be related to beneficial changes in the mix of microbes found in our gut. The results could help identify other foods or supplements with similar nutritional benefits.
Researchers led by Kristina S. Petersen of Texas Tech University in the United States found that. introducing nuts into the diet a person’s diet can alter the mix of microbes in the gut – known as the microbiome – in a way that increases a person’s body’s production of the L-homoarginine amino acid. Homoarginine deficiency has been linked to an increased risk of cardiovascular disease.
Gut microbiota
“Research has shown that nuts may have beneficial effects on the heart, such as. lowering cholesterol levels and blood pressure -explains Mansi Chandra, a researcher at Juniata College, Huntingdon. This motivated us to study how nuts benefited the gut microbiome and whether these effects led to potential beneficial effects. Our findings represent a new mechanism through which nuts may reduce the risk of cardiovascular disease,” she notes.
State-of-the-art technology
The researchers used a method known as metatranscriptomics to study gene expression in intestinal microbes. This newly developed technology can be used to quantify gene expression levels and monitor how they change in response to various conditions, such as changes in diet.
“To our knowledge, this is the first study to use metatranscriptomic analysis to study the impact of nut consumption on gene expression in the gut microbiota,” says Chandra. These exploratory analyses contribute to our understanding of nut-related modulation of the gut microbiome, which could be very impactful in learning how gut health impacts our overall heart health.”
The metatranscriptomic analysis used samples acquired in a previously conducted controlled feeding study in which 35 participants at high cardiovascular risk were subjected to a two-week standard Western diet and then randomly assigned to one of three study diets. Study participants followed each diet for six weeks with a break between each diet.
Fatty acids
The diets included one that incorporated whole nuts, another that included the same amount of omega-3 fatty acid alpha-linolenic acid, or ALAand polyunsaturated fatty acids than the walnut diet but without walnuts, and another 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.
The diets were designed to obtain information on how nuts affected cardiovascular health because of their bioactive compounds and their ALA content, and on whether ALA from walnuts is the best substitute for dietary saturated fats compared to oleic acid.
Bacteria of the gastrointestinal tract.
For the new work, the researchers used metatranscriptomics to analyze gene expression and gastrointestinal tract bacteria from fecal samples collected shortly before participants completed the run-in diet and each of the three diets in the study.
The analysis revealed. higher levels of Gordonibacter bacteria in the gut. of the participants in the walnut diet. This bacterium converts the plant polyphenol ellagitannins and ellagic acid into metabolites that allow their absorption by the body.
Participants who consumed the walnut diet also showed higher levels of expression of several genes involved in important metabolic and biosynthetic pathways, including those that increase the body’s production of the amino acid L-homoarginine.
Although further studies are needed to confirm these observations, the research could help inform nut-based dietary interventions. “Given that many people are allergic to nuts.these findings also suggest that other substances may be beneficial to health,” says Chandra.
Next, the researchers want to apply metabolomic and proteomic analyses to identify the end products of genes that showed higher levels of expression, which would allow them to better understand the biological mechanisms involved.
