Dietary fiber, while indigestible to humans, is a vital element in keeping intestinal bacteria healthy – and this, a growing body of research has revealed, plays a big role in overall health and disease risk. Despite their importance, Americans generally consume much less fiber than recommended, leading to a ‘hunger’ for rapidly changing intestinal bacteria after a high-fiber diet for a short time.
The new study comes from the University of California – Irvine, where researchers found that the intestinal microbiome undergoes major changes after just a few weeks on a high-fiber diet. The research involved feeding the participants a total of 10 unprocessed meals with a high fiber content per week for the two weeks.
The goal was to reach 50 grams of dietary fiber per day, which can come from grains, berries and other plant foods. The researchers used gas chromatography and analyzed samples from before and after the fiber-rich diet to observe the changes it had.
After just two weeks, the researchers found that increased consumption of dietary fiber caused “significant” changes in intestinal bacteria, including an increase in Bifidobacterium, a fiber degrader. However, the short-term diet did not cause any significant increase in short-chain fatty acids.
Katrine Whiteson, co-director of the UCI Microbiome Initiative, said:
The lack of fiber intake in the industrialized world is killing our intestinal microbes, with important health consequences that may be associated with an increase in colorectal cancer, autoimmune diseases and even a decrease in the vaccine’s effectiveness and response to cancer immunotherapy.