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Two specific diets may alter gut microbiota, protect against type 2 diabetes
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Long-term adherence to a Mediterranean or a low-fat, high-complex carbohydrate diet appears to confer protection against type 2 diabetes through specific changes in the gut microbiota, according to recent findings.
In the study, Antonio Camargo Garcia, PhD, of Sofia University Hospital and the University of Cordoba in Spain, and colleagues evaluated a subgroup of 20 men (mean age, 63.3 years) with obesity (mean BMI, 32.2 kg/m2) from the CORDIOPREV study, an ongoing prospective, randomized, opened, controlled trial in patients with coronary heart disease. Besides conventional CHD treatment, participants were randomly assigned to consume a Mediterranean diet or a low-fat, high-complex carbohydrate diet.
Analysis of microbiota community was conducted on 40 fecal samples, 20 taken at baseline and 20 after 1 year of dietary adherence. Plasma samples also were collected and analyzed. The researchers evaluated the bacterial consumption of these samples and analyzed the relationship between the diets, gut microbial ecology and changes in fecal and plasma metabolites.
The researchers found that adherence to the low-fat, high-complex carbohydrate diet resulted in an increased relative abundance of Prevotella bacterial genus, whereas the Mediterranean diet led to a decrease (time by diet interaction, P = .28). Moreover, the Mediterranean diet was associated with an increase in the relative abundance of Roseburia (P = .017) and Oscillospira (P = .001). The low-fat, high-complex carbohydrate diet was associated with a decrease in the abundance of Roseburia (time by diet interaction, P = .009) and no change in Oscillospira (time by diet interaction, P = .016). Long-term intake of the Mediterranean diet was found to increase the relative abundance of Parabacteroides distasonis (P = .025) and the low-fat, high-complex carbohydrate diet increased the abundances of Faecalibacterium prausnitzii (P = .02).
Overall, 572 compounds were detected in the feces, with 37 showing significant interaction between time and diet. The main diet-generated change to the fecal specimens was in amino acids, peptides and sphingolipid metabolism. The researchers found that changes in seven of 572 fecal metabolites and three of 697 plasma metabolites were linked to changes in three bacterial genera and two bacterial species.
“Our study provides insight into microbial functions and their role in mediating the effect of diet when used as therapeutic tool in human health; however, further studies are required to fully understand the potential role of gut microbiota modification by diet in the prevention of metabolic diseases,” the researchers wrote. – by Jennifer Byrne
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Meghan Jardine, MS, MBA, RD, LD, CDE
This study adds to the research demonstrating the important role diet plays in the diversity of the human gut, potentially improving the health of the host. It would be interesting to know which specific components of the Mediterranean diet and the low-fat, high–complex carbohydrate diet increase the genera Roseburia and the species Faecalibacterium prausnitzii, respectively. This could potentially provide guidelines maximizing the benefits of each dietary pattern. I would think the benefits come from high-fiber, plant-based foods, such as legumes, whole grains, vegetables and fruits. In my practice I recommend patients consume at least one to two servings of high-fiber, nutrient-dense foods at each meal to reduce postprandial glycemic response and improve satiety. These foods are also improving the composition of their microbiota; improving gut-barrier function, reducing inflammation, increasing insulin sensitivity, and perhaps even positively affecting fatty acid metabolism. Foods that are known to modulate microbiota are prebiotics, which are indigestible oligosaccharides that are fermented in the large intestine, a process that potentially changes the composition and activity of the microbiota. Foods to focus on include oatmeal, legumes, onions, garlic, whole grains and bananas. Legumes — beans, peas, and lentils — are a great choice as they are potent prebiotics and staples of many dietary patterns and provide an inexpensive source of protein. Legumes can be easily added to soups and stews, topped on salads, made into a dip (bean dip or hummus) or as served as the main dish in a vegetarian meal.
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