Researchers at Cornell University have found that the effectiveness of dietary fiber in promoting healthy digestion may depend on the specific strains of gut bacteria present in an individual's microbiome. The study, published in Microbiology Spectrum, highlights the importance of having the right bacterial species and strains to effectively process resistant starches, a type of dietary fiber.
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Dietary fiber plays a crucial role in preventing constipation, supporting beneficial gut microbes, and aiding in blood sugar regulation. It is abundant in legumes, nuts, seeds, vegetables, fruits, and whole grains. Previous research on resistant starches yielded inconsistent results, with some individuals experiencing benefits while others did not. Angela Poole, assistant professor in the Division of Nutritional Sciences and the senior author of the study, noted that the presence of appropriate bacteria is essential to process these starches effectively.
The researchers employed advanced techniques to analyze strains of the gut microbe Bifidobacterium adolescentis, discovering distinct responses among different strains when exposed to resistant starches. This finding underscores the need to investigate bacteria at the strain level for precision nutrition applications.
Most prior studies utilized 16S sequencing to identify bacterial presence, whereas this research employed shotgun metagenomics, allowing for strain-level identification and gene analysis. Fecal samples from over 50 participants were collected, and subsequently, they were given three types of crackers containing two varieties of resistant starch and a control starch that did not require bacterial breakdown.
The research team utilized a sensitive bioinformatics tool, Cayman, revealing previously uncharacterized bacteria that increase in response to resistant starch, indicating their potential role in carbohydrate processing. Future studies will delve deeper into the functions of these bacteria.
Poole emphasized the significance of knowing the specific strains present in individuals, particularly when tailoring diets for conditions such as diabetes. Advanced tools will help nutritionists identify the relevant genes and enzymes among bacteria to determine if patients can benefit from specific dietary fibers.