Written by Marcia J. Egles, MD. Data suggest that dietary polyphenols may act in the gut to modify microbial community structure, resulting in lessened intestinal and systemic inflammation and improved metabolic outcomes.
A study from Rutgers University demonstrates how specific dietary changes can dramatically alter certain populations of gut bacteria which may confer some protection against the adverse metabolic consequences of a high fat diet. The study was performed in mice with grape polyphenols supplementing a high fat diet 1. The study showed that dietary polyphenols, which are known to be poorly absorbed and poorly digested, may act in the gut through a mechanism involving a bloom in the population of the bacterium Akkermansia muciniphila 1.
In humans, metabolic syndrome is a clustering of at least three of the five conditions of obesity, hypertension, dyslipidemia, insulin resistance, and hyperglycemia. Metabolic syndrome increases the risk of developing type2 diabetes mellitus and cardiovascular disease2. The reported study uses an animal model of metabolic syndrome achieved by feeding a high fat diet to mice.
Polyphenols are a broad classification of complex molecules- the term means “many” from poly and phenols which are a class of molecules having phenol carbon-rings in their structure. The classification includes many substances, many of them from plants.
In the study, young male mice were divided into 3 groups of fifteen mice each. One group received a high fat diet (HFD) for 13 weeks. The second group received the same HFD plus 1% Concord grape polyphenols (GP) for 13 weeks. Since the grape polyphenols were fed to the mice by means of a soy protein delivery system, a third group of 15 mice also received the HFD and just the soy protein without the grape polyphenol. These three diets were equivalent in the amount of calories and fat/carbohydrate/protein consumed per day per mouse. Finally, for comparison to a more normal state, a fourth group of mice received a low fat diet, (LFD), which was comparatively far lower in daily calories but had the same mass of daily food as the HFD.
Despite having eaten the equivalent amount of fat as the other two HFD groups, the mice in the grape polyphenol HFD group maintained significantly less adiposity as well as significantly lower body weight over the 13 weeks compared to the other HFD mice. The GP group was approximately intermediate in body weight and adiposity between the LFD mice and the other two HFD groups. At the end of the trial, the livers of the GP fed mice were similar in weight to those of the LFD mice. The livers of the other two HFD groups of mice were significantly (p value less than 0.05) heavier. The liver lipid content of the GP mice was significantly (p less than 0.016) lower than the other HFD mice as well.
In general, the GP diet mice showed significantly better glucose tolerance than their HFD counterparts at 3, 6, and 9 weeks’ checks. The level of glucose tolerance in the GP mice was still somewhat impaired in comparison to the normal LFD mice.
Unlike the HFD mice, the GP mice had undetectable levels of Interleukin-6 (IL-6) indicating that GP attenuates systemic inflammation. Several other markers of inflammation were similarly improved in the GP mice as compared to the HFD mice.
Gene sequencing was performed on the mice gut contents and feces in order to precisely identify the range of bacteria present. As had been reported previously,3 the microbial flora of mice are dominated by bacteria from the Firmicutes and Bacteroidetes types. The consumption of a high fat diet increases the populations of Firmicutes relative to Bacteroidetes.
As expected, the gut microflora in the two HFD groups without the GP became dominated by Firmicutes. By contrast, the gene sequencing for the GP mouse gut and fecal microbia revealed an abundant bloom (an increase) of Akkermansia muciniphila and a reduction in the populations of the other bacterial types.
The researchers noted that their results were “strikingly consistent” with another study in which cranberry polyphenol supplementation decreased body and liver weight gain in mice, improved glucose and insulin tolerance, lowered plasma triglycerides, reduced markers of inflammation, and increased the relative abundance of Akkermansia muciniphila 4.
These data suggest that dietary polyphenols may act in the gut to modify microbial community structure, resulting in lessened intestinal and systemic inflammation and improved metabolic outcomes.
Source: Roopchand, Diana E., Rachel N. Carmody, Peter Kuhn, Kristin Moskal, Patricio Rojas-Silva, Peter J. Turnbaugh, and Ilya Raskin. “Dietary polyphenols promote growth of the gut bacterium Akkermansia muciniphila and attenuate high-fat diet–induced metabolic syndrome.” Diabetes 64, no. 8 (2015): 2847-2858.
© 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.
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Posted March 27, 2019.
Marcia Egles, MD, graduated from Vanderbilt University School of Medicine in 1986. She completed her residency in Internal Medicine at St. Louis University Hospital. Dr. Egles is certified in Internal Medicine and is a member of the American College of Physicians. She resides in Avon, IN with her husband and two sons.
References:
- Roopchand DE, Carmody RN, Kuhn P, et al. Dietary polyphenols promote growth of the gut bacterium Akkermansia muciniphila and attenuate high-fat diet–induced metabolic syndrome. Diabetes. 2015;64(8):2847-2858.
- Wilson PW, D’Agostino RB, Parise H, Sullivan L, Meigs JB. Metabolic syndrome as a precursor of cardiovascular disease and type 2 diabetes mellitus. Circulation. 2005;112(20):3066-3072.
- Turnbaugh P, Backhed F, Fulton L, Gordon JI. Diet-induced obesity is linked to marked but reversible alterations in the mouse distal gut microbiome. Cell host & microbe. 2008;3(4):213-223.
- Anhê FF, Roy D, Pilon G, et al. A polyphenol-rich cranberry extract protects from diet-induced obesity, insulin resistance and intestinal inflammation in association with increased Akkermansia spp. population in the gut microbiota of mice. Gut. 2015;64(6):872-883.
