New Research Highlights Benefits of Specific Dietary Fiber
Recent studies on gut microbiomes have sparked a significant shift in nutritional science. Over the past few years, dietary fiber has gained recognition—some even call it the “new protein,” as it’s frequently added to foods to nourish our gut microorganisms and promote health.
However, a 2024 study involving mice indicates that not all fiber supplements offer the same advantages. A particular fiber found in oats and barley, known as beta-glucan, appears to help manage blood sugar levels and support weight loss in mice on a high-fat diet.
Researchers from the University of Arizona and the University of Vienna observed weight and fat reduction in the mice after 18 weeks with beta-glucan. In contrast, other fibers like wheat dextrin, pectin, resistant starch, and cellulose had no similar outcomes, although they did change the composition of the mouse microbiome compared to those without fiber supplements.
“We know fiber is important, but there’s a lot of different kinds,” noted biomedical scientist Frank Duca from UA last July. “We aimed to identify which fibers would be most beneficial for weight loss and glucose regulation, hoping to better inform both consumers and the agricultural sector.”
Dietary fibers serve as a primary energy source for gut bacteria, yet surprisingly, fewer than 5 percent of Americans meet the recommended daily intake of 25–30 grams of fiber.
In response to this, fiber supplements and foods enriched with “invisible fiber” are becoming more popular. But with so many types, it can be quite overwhelming to decide which ones to choose.
Some fibers, like oat beta-glucans and wheat dextrin, dissolve in water and are easily fermented by gut bacteria. Others, like cellulose and resistant starch, are less soluble and help form stool.
A key aspect of the current study was its comprehensive analysis of various fibers in a single group of mice. The researchers found that only beta-glucan increased the prevalence of a specific bacterium called Ileibacterium, which has been associated with weight loss in previous studies.
Notably, mice consuming beta-glucan showcased reduced weight and fat content well before reaching the 10-week point. This aligns with an earlier study by Duca, where rats fed barley flour, rich in beta-glucan, lost weight even while maintaining their intake of a high-fat diet.
Additionally, mice on beta-glucan diets had higher levels of butyrate in their guts, which results from fiber breakdown by microbes. Butyrate is crucial because it stimulates the release of glucagon-like peptide-1 (GLP-1), a natural protein that mimics drugs like Ozempic, promoting insulin secretion.
“One of the benefits of fiber is linked to GLP-1 and other gut peptides that manage appetite and weight,” explained Duca. “Still, we believe there are other positive effects from butyrate that might contribute to health, such as enhancing gut barrier function and influencing organs like the liver.”
While these findings are promising, more research is necessary before applying them to human diets. The results, however, suggest that some fibers could be more effective for weight loss and insulin management than others.
This study was published in the Journal of Nutrition.
