A Low Glycemic Index Mediterranean Diet Combined with Aerobic Physical Activity Rearranges the Gut Microbiota Signature in NAFLD Patients
A low-glycemic index Mediterranean diet and aerobic exercise corrects gut microbial imbalance in people with fatty liver disease.
Non-alcoholic fatty liver disease, or NAFLD, is a syndrome that encompasses multiple states of liver dysfunction, including steatosis (fatty liver), nonalcoholic steatohepatitis, and cirrhosis. It is the most common liver chronic liver condition among people living in the United States, affecting roughly 90 percent of people with obesity, or about 25 percent of the overall population. A dominant feature of NAFLD is dysbiosis, an imbalance in the types and numbers of microbes in the gut. Findings from a recent study suggest that eating a low-glycemic index Mediterranean diet and engaging in aerobic exercise restores gut microbial balance in people with NAFLD.
Glycemic index refers to a value (between 0 and 100) assigned to a defined amount of a carbohydrate-containing food based on how much the food increases a person’s blood glucose level within two hours of eating, compared to eating an equivalent amount of pure glucose, which has a value of 100. Whereas eating high glycemic index foods induces a sharp increase in blood glucose levels that declines rapidly, eating low glycemic index foods generally results in a lower blood glucose concentration that declines gradually.
The Mediterranean dietary pattern is rich in foods that have a low glycemic index, including fruits, vegetables, olive oil, legumes, fish, and poultry. Previous research demonstrated that a Mediterranean diet in conjunction with aerobic exercise improves measures of NAFLD but did not identify the mechanism that drove these improvements.
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The current study involved 109 adults (average age, 53 years) who had been diagnosed with NAFLD. The investigators randomly assigned the participants to receive one of six interventions: low glycemic index Mediterranean diet; aerobic exercise program (with or without the low glycemic index Mediterranean diet); combined aerobic exercise and resistance training program (with or without the low glycemic index Mediterranean diet); or no intervention. The investigators collected stool samples from the participants and sequenced the microbial populations in the samples.
They found that compared with other dietary/exercise interventions, a low-glycemic index Mediterranean diet in conjunction with aerobic exercise exerted robust effects on the participants' gut microbial population. These effects corrected the participants' dysbiosis and promoted increases in populations of microbes that benefit gut health, including Akkermansia, Firmicutes, and Ruminococcaceae.
These findings suggest that dietary measures in conjunction with exercise have favorable effects on the gut microbiota of people with NAFLD, providing insights into the mechanisms that drive improvements in disease status. Evidence from cell culture studies suggests that berberine, a bioactive dietary compound, provides protection against NAFLD. Read our overview article to learn more about berberine.