We know that eating fruits, vegetables, and whole grains is good for us because they provide dietary fiber. But why is fiber so beneficial?
A team of researchers has discovered that dietary fiber plays a crucial role in maintaining the balance between the production of healthy and harmful substances in our gut by influencing the behavior of bacteria in the colon.
Scientists from the DTU National Food Institute and the University of Copenhagen have uncovered how dietary fiber impacts our health.
The research, published in the journal Nature Microbiology, reveals that different types of bacteria in our colon compete to use an essential amino acid called tryptophan.
This competition can lead to either positive or negative outcomes for our health.
When we eat a lot of dietary fiber, our gut bacteria help convert tryptophan into healthy substances. However, if we don’t consume enough fiber, tryptophan can be turned into harmful compounds by our gut bacteria.
“These findings highlight how our dietary habits significantly affect the behavior of gut bacteria, creating a delicate balance between promoting health and causing disease.
In the long term, this research can help us design diets that prevent various diseases,” says Tine Rask Licht, a professor at DTU National Food Institute.
The study shows that dietary fiber prevents the conversion of tryptophan into harmful substances and promotes its transformation into beneficial compounds.
For example, the gut bacterium E. coli can turn tryptophan into a harmful compound called indole, which is linked to chronic kidney disease. In contrast, another gut bacterium, C. sporogenes, converts tryptophan into healthy substances that protect against inflammatory bowel diseases, type 2 diabetes, cardiovascular diseases, and neurological diseases.
Through experiments with bacterial cultures and mice, the researchers demonstrated that fiber-degrading gut bacteria, such as B. thetaiotaomicron, regulate the harmful activity of E. coli. “B. thetaiotaomicron helps by breaking down fibers into simple sugars, which E. coli prefers over tryptophan for growth.
These sugar components prevent E. coli from turning tryptophan into indole, allowing C. sporogenes to use tryptophan to produce healthy compounds,” explains Anurag Kumar Sinha, a researcher at DTU National Food Institute.
Understanding the behavior of gut bacteria is essential. While dietary fiber can change the types and amounts of bacteria in our gut, it also influences how these bacteria act.
“We need to shift our focus from viewing gut bacteria as strictly good or bad and instead understand how to make them behave beneficially,” says Martin Frederik Laursen, an associate professor at DTU National Food Institute.
This new understanding can help scientists create better dietary recommendations to keep our gut healthy and prevent diseases.
Essential amino acids like tryptophan, which we must get from food, are found in protein-rich foods such as chicken, turkey, salmon, tuna, eggs, milk, cheese, yogurt, legumes, nuts, and seeds. Dietary fiber is abundant in fruits, vegetables, and whole grains.
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