In a nutshell
This review looked at the effect of a fiber-rich diet on the microbiome for patients with diabetes. It found that high-fiber diets led to more healthy bacteria in the gut, and may improve glucose control.
Some background
The microbiome consists of bacteria and other microorganisms which live on the skin and in the gut. A healthy gut microbiome includes thousands of species of bacteria. The food a person eats impacts which bacteria will thrive in their gut. The microbiome plays a role in multiple diseases, including type 2 diabetes (T2D). People with T2D have different dominant bacterial species in their microbiomes.
Fiber is one of the most important foods for the microbiome. Soluble fiber, such as in oatmeal, includes short starches which are not digestible by humans. Beneficial bacterial species ferment this fiber into short-chain fatty acids (SCFAs). These SCFAs influence hunger by causing the release of hormones including GLP-1. Eating more soluble fiber supports beneficial species, and prevents overgrowth of other species.
The role of fiber on the microbiome is not well studied in people with T2D. It is not clear whether fiber can improve T2D or the microbiome of people with T2D.
Methods & findings
This review included nine studies of patients with T2D. Eight studies randomly had half of the patients begin eating a high-fiber diet. One study compared people who were already eating a high-fiber or low-fiber diet.
Two studies with 80 participants looked at Bifidobacterium, which are a beneficial group of SCFA-producing bacteria. Patients taking fiber had significantly more Bifidobacterium bacteria as a percentage of their microbiome. Fiber also increased total SCFA, as data from 95 patients showed.
Glycated hemoglobin (HbA1c) is a measure of blood sugar control over the previous two to three months. Data on HbA1c were combined from 8 studies with 599 participants. The fiber group had a small but significant improvement in HbA1c (reduction of 0.18%). However, there was no improvement in the body’s ability to respond to the hormone insulin (no change in HOMA-IR).
There were no severe side effects of fiber. Some patients reported diarrhea or loose stool.
The bottom line
This review found that dietary fiber alters the gut microbiome for patients with T2D, and may improve glucose control.
The fine print
The microbiome is an emerging field. Research is ongoing into the complex relationships between different species.
Published By :
Nutrients
Date :
Oct 27, 2020
