As more people around the world grapple with poor gut health brought on by obesity, a new literature review conducted at the University of Michigan suggests that a gut friendly diet can positively impact gut microbiome health and may help with weight loss too.
In an invited review article recently published in the medical journal, “Current Opinion in Clinical Nutrition and Metabolic Care,” Research Professor Zora Djuric, Ph.D. of the Department of Family Medicine found that by including more fiber, plant-based foods, omega-3 fatty acids and whole grains, people can mitigate the adverse health effects of high fat diets and obesity on their microbiome.
Obesogenic diets—typically characterized by high levels of saturated fat, sugar and processed foods, along with low fiber consumption — throw our gut microbiomes out of balance and can trigger negative impacts on health. This imbalance, called dysbiosis, has been linked to increased levels of inflammation, irritable bowel syndrome, and even mental health problems. According to Djuric’s analysis, eating a wide variety of gut-friendly foods and macronutrients appears to normalize this dysbiosis and could help people live healthier lives.
The Effects of Calorie Reduction on the Gut Microbiota
Eating fewer calories can have many beneficial effects beyond weight loss. Studies have demonstrated that calorie-reduced diets can increase the abundance of beneficial bacterial species, such as Bacteroidetes and Akkermansia, while reducing the prevalence of harmful bacterial species, like Firmicutes.
A high-fiber, plant-based diet, on the other hand, has been shown to promote healthier gut microbiomes by reducing Firmicutes levels and increasing amounts of Bacteroidetes. This balance in microbiota composition has been associated with improved metabolic health, reduced inflammation, and enhanced intestinal barrier function.
Specific foods mentioned in the literature as beneficial to the promotion of Bacteroidetes are black and green tea, as well as red grapes. These foods contain micronutrients that reach the colon where most of the gut bacteria are found. One study suggests that the effect of a calorie restricted diet was greatest when that diet contained a mixture of yogurt, fruits and vegetables.
The Effects of Dietary Fiber on the Gut Microbiota
Increased intake of dietary fiber has been linked to a healthier gut microbiota composition. Dietary fibers, particularly fermentable fibers, act as prebiotics that promote the growth of beneficial bacterial species. These species, in turn, produce short-chain fatty acids, which are absorbed in our gut and have many anti-inflammatory and immunomodulatory effects. Studies have shown that high-fiber diets can help to counter the dysbiotic effects of unhealthy diets and improve gut health, with potential benefits for metabolic health and obesity management.
The Effects of Dietary Fat Type on Gut Microbiota
The type of dietary fat also plays a crucial role in shaping gut microbiota composition. Saturated fatty acids have been associated with dysbiosis and increased inflammation, whereas omega-3 polyunsaturated fatty acids appear to have favorable effects on gut microbiota composition and function. Research suggests that replacing saturated fats with plant-based monounsaturated fatty acids and omega-3 polyunsaturated fatty acids in the diet can help to alleviate dysbiosis and improve gut health in individuals consuming high-fat diets.
Summary and Conclusions
This literature review underscores the importance of adopting healthier food choices to combat the negative effects of obesogenic diets on gut health. By focusing on calorie restriction, increasing dietary fiber intake, and improving fat quality, individuals can normalize dysbiosis, support their gut health, and potentially reduce the risk of obesity-related complications.
“Obesity is on the rise worldwide and it is important to develop strategies that can mitigate the adverse health effects of obesity,” Djuric writes. “Unfortunately, weight loss via any means is difficult to maintain in humans, and weight regain is common. This review focuses on identifying dietary factors outside of calorie restriction that could be used to mitigate the adverse health effects of obesity.
“These data support the design of dietary interventions that would allow individuals to focus on diet quality independently of weight loss to mitigate the adverse (effects) of obesity.”
Djuric’s new study, called the “MyBestGI” study, is now evaluating three different methods to improve diet quality in a randomized trial. More information about this study can be found at MyBestGI.org.
Djuric, Z. (2023). Dietary approaches for normalizing dysbiosis induced by high-fat, obesogenic diets. Current Opinion in Clinical Nutrition & Metabolic Care, 26(3), 293–301. https://doi.org/10.1097/mco.0000000000000917