Dietary Fiber: Some Meals May Be Too High In Fructose
Although commonly recommended for healthy weight loss, a new study suggests that when consuming low-fructose diets, high fructose intake could result in higher frequency of bacterial fermentation in the intestine that may lead to a loss of beneficial gut bacteria and inflamed GI tract.
High fructose diets have been found to interfere with the metabolism of good bacteria and affect gut health. High fructose diets have been found to interfere with the metabolism of good bacteria and affect gut health.
According to the American Heart Association (AHA), over 70 percent of adults and 70 percent of children in the United States currently consume a high-fructose diet. This does not take into account the part played by excessive intake of fructose (the "fake sugar" of pop, soft drinks, and other processed foods) in the fatty acid diet intake by the same populations.
In 2003, the AHA and the U.S. Department of Agriculture introduced a dietary guideline that called for a minimum intake of 10 grams of fiber per day.
This was a revised and updated recommendation, as previously, the USDA recommended 5 grams per day. Since that time, the National Institutes of Health (NIH) have revised their guidelines again, which require a minimum fiber intake of 9 grams.
The dietary guidelines are in place to protect against obesity, but scientists have not shown how dietary fiber affects the effect of these dietary recommendations.
"For a long time, the Dietary Guidelines have primarily focused on carbohydrate intake and recommended a low-fiber diet in response to a lack of fiber-like phenols," says lead author Erik Ulin, Ph.D., of the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.
"But as scientists have refined our understanding of how diet regulates the microbiota in the gut and how the microbiota influence our health, we have shifted our interest from simple carbohydrate intake to understanding how dietary fiber affects metabolic processes," he adds.
Ulin and colleagues conducted a study to determine if a low-fiber diet could interfere with the act of fermentation by better performing the fermentation.
Dietary fiber lowers likelihood of organic gut bacteria
To test this hypothesis, the researchers focused on white wine and low-fiber diets in mice. In the experiment, the team fed the mice a low-fiber diet containing 50 grams of fiber per day, whereas the mice that fed on an equal amount of white wine that had no fiber had a metabolic diet comprising 6 grams of fiber per day.
Through a series of experiments, the researchers were able to determine that when the mice consumed a low-fiber diet, their microbiota composition was altered through the nutrient diet, which eliminated better-adapted gut bacteria, or Lactobacillus.
Specifically, Lactobacillus positively responded to a high fiber diet and decreased the total bacterial concentrations.
Mice that consumed low-fiber diets were then exposed to different bacterial strains that persisted in response to the treatment. However, the researchers were surprised to find that the amount of bacterial production in this study was not directly proportional to the amount of fiber consumed.
"These results suggest that the inflammatory effect of low-fiber diets could be similar to other common gut bacteria like salmonella and streptococcus," says the study's lead author, Thien Pham, Ph.D., a postdoctoral fellow in the Department of Endocrinology at Penn.
"Additionally, this suggests that keeping a more balanced diet may be better than doubling fiber." Thien Pham
The researchers acknowledge that their findings may not apply to humans; they did not control for diet intake or drink. They plan to conduct a similar study in humans that further examines the relationship between fiber intake and gut bacteria.