Walnuts<\/a> are rich in omega-3 fatty acids, phytochemicals<\/a> and antioxidants making them unique compared to other foods<\/a>. Consuming walnuts has been associated with health benefits including a reduced risk of heart disease and cancer<\/a>. Dysbiosis<\/a> of the gut<\/a>microbiome<\/a> has been linked to several chronic diseases<\/a>. One potential mechanism by which walnuts may exert their health benefit is through modifying the gut microbiome. <\/p>\n\n\n\n This study identified the changes in the gut microbial communities that occur following the inclusion of walnuts in the diet<\/a>. <\/p>\n\n\n\n Male Fischer 344 rats<\/a> (n<\/em>=20) were randomly assigned to one of two diets for as long as 10 weeks: (1) walnut (W), and (2) replacement (R) in which the fat<\/a>, fiber, and protein in walnuts were matched with corn oil, protein casein<\/a>, and a cellulose fiber<\/a> source. Intestinal samples<\/a> were collected from the descending colon<\/a>, the DNA isolated, and the V3-V4 hypervariable region<\/a> of 16S rRNA gene<\/a> deep sequenced on an Illumina MiSeq<\/a> for characterization of the gut microbiota<\/a>. <\/p>\n\n\n\n Body weight<\/a> and food intake<\/a> did not differ significantly between the two diet groups.<\/p>\n\n\n\n The diet groups had distinct microbial communities with <\/strong>animals<\/strong><\/a> consuming walnuts displaying significantly greater <\/strong>species diversity<\/strong><\/a>. Walnuts increased the abundance of <\/strong>Firmicutes<\/strong><\/a><\/em> and reduced the abundance of <\/strong>Bacteriodetes.<\/strong><\/em> <\/strong><\/p>\n\n\n\n Walnuts enriched the <\/strong>microbiota<\/strong><\/a> for probiotic-type bacteria including <\/strong>Lactobacillus<\/strong><\/a><\/em>, <\/strong>Ruminococcaceae<\/strong><\/a><\/em>, and <\/strong>Roseburia<\/strong><\/a><\/em>.<\/strong><\/p>\n\n\n\n While significantly reducing <\/strong>Bacteroides<\/strong><\/a><\/em> and <\/strong>Anaerotruncus<\/strong><\/em>. The class <\/strong>Alphaproteobacteria<\/strong><\/a><\/em> was also reduced. <\/strong><\/p>\n\n\n\n Walnut consumption altered the gut microbial community suggesting a new mechanism by which walnuts may confer their beneficial health effects.<\/strong><\/p>\n\n\n\n