- Researchers have previously identified an association between fiber intake and positive health outcomes.
- Fiber promotes a healthy gut microbiome once bacteria metabolize it.
- A recent study found that a two-week increase in fiber intake significantly altered the intestinal microbiome.
Researchers have found that an increase in fiber intake of two weeks can significantly alter the intestinal microbiome, including increasing species of bacteria that break down fiber.
However, the amount of short chain fatty acids (SCFAs) has not increased. SCFAs are the result of the breakdown of bacteria, and they have different roles in the body.
For example, SCFAs are used as a
The research, which appears in the journal mSisteme, lays the foundation for future studies to investigate the link between fiber intake, intestinal bacteria and SCFAs in more detail.
Fiber plays an important role in human health. For example, a recent review of various meta-analyzes found that people who eat the most fiber significantly reduced their chances of dying from a cardiovascular event.
However, only 1 in 20 people in the United States consumes the recommended amount of fiber.
According to Dr. Katrine Whiteson, associate professor of molecular biology and biochemistry, co-director of the University of California, Irvine (UCI) Microbiome Initiative, and co-author of the current study:
“The lack of fiber intake in the industrialized world is starving our intestinal microbes, with important health consequences that can be associated with increased colorectal cancer, autoimmune diseases and even reduced vaccine efficacy and response to cancer immunotherapy.”
The small intestine cannot digest fiber. According to the authors of the current study, it passes into the colon, where microbes can break down the fiber.
This process leads to the production of SCFAs. Experts believe that it is important for a variety of factors that affect a person’s health.
The authors of the present study wanted to study the association between a short-term increase in dietary fiber, the composition of the intestinal microbiome, and the presence of SCFAs.
To investigate, the researchers conducted a study in which 26 undergraduate students participated in a biology course at UCI, as well as their instructors.
In week 1, participants ate their normal diet and were given three stool samples for analysis.
In week 2, the participants started with a high-fiber diet. They tracked their nutritional intake using a fitness program, which targeted 40 grams of fiber each day. To help, the researchers provided ten meals each week that contained lots of fiber from different plants.
In the third week, participants were encouraged to increase their fiber intake to 50 g per day. During this week, participants provided three more stool samples.
According to graduate student Andrew Oliver, a teaching assistant for the course, “students increased their fiber intake by an average of 25 g per day, but the variability of the fiber intake before the intervention was significant.”
A few students had to go from almost zero to 50 g daily. We all got a little obsessed with how much fiber we had in the food. ‘
The researchers then analyzed the samples using DNA sequencing to identify the composition of the bacteria. They used gas chromatography to measure SCFAs.
The researchers found that the composition of the intestinal microbiome of the participants changed by about 8% following the diet intervention.
This was mainly due to increases in bacteria known to break down fiber, including Bifidobacterium, Bacteroides, en Prevotella.
However, the researchers did not see any statistically significant increase in SCFAs. They speculate that this may be because stool samples do not accurately represent the levels of SCFAs in the intestines, which occur mainly in the cell walls of the intestines.
The researchers also suggest that the two-week intervention may not have been long enough to see any difference in SCFAs.
According to dr. Whiteson, “we hope to make longer interventions in dietary fiber and study how fiber can support the gut microbiome and promote health.”
“Right now during a pandemic, when we need our immune health and healthy vaccine responses, we encourage everyone to think about the plant variety of their diets and to add beans, berries and avocados where they can.”