Short-Term High-Fiber Diets Trigger Major Changes In 'Starving' Gut Bacteria

Dietary fiber, though indigestible by humans, is a vital element for keeping one's gut bacteria healthy — and that, an increasing body of research has revealed, plays a big role in one's overall health and disease risk. Despite its importance, Americans generally consume far less fiber than recommended, leading to 'starving' gut bacteria that quickly change after a short-term high-fiber diet.

The new study comes from the University of California – Irvine, where researchers found that the gut microbiome experiences major changes after only a couple of weeks spent eating a high-fiber diet. The research involved feeding participants a total of 10 high-fiber unprocessed meals weekly for the two weeks.

The goal was to hit 50 grams of dietary fiber a day, which can come from things like grains, berries, and other plant-based foods. The researchers used gas chromatography and analyzed samples from before and after the high-fiber diet to observe the changes it had.

After only two weeks, the researchers found that increased dietary fiber consumption caused 'significant' gut bacteria changes, including an increase in Bifidobacterium, a fiber-degrader. However, the short-term diet wasn't found to cause any significant increase in short-chain fatty acids.

UCI Microbiome Initiative co-director Katrine Whiteson said:

The lack of fiber intake in the industrialized world is starving our gut microbes, with important health consequences that may be associated with increases in colorectal cancer, auto-immune diseases and even decreased vaccine efficacy and response to cancer immunotherapy.