Walnut Consumption Changes the Relative Abundance of Bacteroidetes and Firmicutes in the Gut

• Published in: The FASEB journal Vol. 29; no. S1
• Main Authors: Byerley, Lauri, Ponder, Monica, Lorenzo, Brittany, Banks, Shelia, Taylor, Christopher, Luo, Meng, Blanchard, Eugene, Welsh, David
• Format: Journal Article
• Language: English
• Published: 01-04-2015
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.29.1_supplement.1006.1

Abstract only
Eating walnuts is associated with health benefits that include reducing the risk of heart disease and cancer. These chronic diseases are linked to changes in the gut microbiome; for example, a shift in the abundance of Firmicutes (F) to Bacteroidetes (B). Food is also known to modulate gut microbes. One way walnuts may exert their health benefits is by altering the gut microbiome. This study investigated walnut's effects on the two major gut bacterial phyla, F and B. Male Fischer 344 rats (n=20) were randomly assigned to one of two diets for 6 or 13 weeks: 1) walnut‐enriched (W) containing approximately 2 servings, and 2) replacement (R) in which walnuts were substituted by corn oil, additional protein and fiber. After 6 or 13 weeks, fecal samples were collected from the descending colon, the DNA isolated and analyzed. The V3 hypervariable region of 16S rRNA gene was deep sequenced on an Illumina MiSeq. The data were analyzed using the UPARSE and QIIME pipeline. Body weight (W: 340
+
24 g vs R: 340
+
24 g) and food intake (W: 15.4
+
2.6 g/day vs R: 14.9
+
2.0 g/day) did not differ significantly. F and B were the most abundant phyla present regardless of diet and constituted about 90% of the microbes detected. The length of time the diet was consumed did not change the relative abundance of F and B. However, inclusion of walnuts in the diet significantly altered the relative abundance of F and B, increasing the ratio of F to B (W: 3.2
+
0.15 vs R: 1.8
+
0.18, p<0.002). These data suggest a new mechanism, changing the gut microbial environment, by which walnuts may exert their beneficial health effects. (Support: California Walnut Commission)