Effect of a High Flavonoid Supplement on Intestinal Inflammation, Short Chain Fatty Acids, and the Gut Microbiome

Abstract

Abstract Objectives Endurance exercise is a known cause of intestinal inflammation. Recent studies suggest that dietary flavonoids may protect the gut from chronic low-grade inflammation and have other effects at the gastrointestinal barrier. As a result, the purpose of this study was to determine the effects of a high flavonoid supplement containing blueberry, green tea, and cocoa on gut health. We investigated changes in intestinal inflammation, fecal short chain fatty acids (SCFA), and the gut microbiome in a randomized clinical trial. Methods In a double-blind, crossover design, 12 recreationally-active cyclists (VO2 max: 43.2 + 5.9 ml/kg/min) completed two 15-day supplementation periods with either a high flavonoid supplement or placebo. The high flavonoid beverage (HFB, 490 mg total flavonoids) and macronutrient-matched low flavonoid control (LFB, 5 mg flavonoids) were consumed once daily, two hours prior to training. Stool samples were collected once during days 9–11 of each intervention to determine microbiome composition and SCFA (acetic, propionic, butyric, isobutyric, valeric, isovaleric, and caproic acid). Fecal calprotectin was used as a marker of intestinal inflammation. Results Food frequency questionnaires estimated that the participants’ average weekly consumption of total flavonoids was 634.7 ± 194.6 mg, with the highest subgroups being flavan-3-ols, flavonols, and anthocyanidins (296.3 ± 169.3, 136.5 ± 21.9, 109.6 ± 35.4 mg, respectively). There was no significant difference in fecal calprotectin on the HFB versus LFB (P > 0.05). Average fecal calprotectin were low (HFB: 12.9 ± 1.2, LFB: 12.9 ± 0.9 ug/g stool), suggesting that subjects had low overall gut inflammation. There were no significant differences in individual and total SCFA (P > 0.05). The total SCFA on the HFB treatment was 115.1 ± 11.3 mM/g vs. 107.9 ± 9.7 mM/g on the LFB. Furthermore, there were no differences in any measures alpha or beta diversity as a result of the dietary intervention (P > 0.05). Conclusions Fifteen-day consumption of a blend of blueberry, cocoa, and green tea flavonoids did not significantly affect gut inflammation, SCFA content, and alpha or beta diversity of the gut microbiome. Funding Sources Build Dairy.