Scientists used a mouse model to investigate how different types of fiber affect the microbiome differently. They studied which fiber benefits particular bacteria in the gut.
The increased Western trend of eating includes refined carbs, saturated fats, and low fiber food. However, it is not healthy for our gut microbiome.
The gut microbiome helps in digestion, boosts the immune system. Moreover, it provides indirect benefits to the mental and cardiometabolic system.
A recently WHO-commissioned meta-analysis showed that 25 to 29 grams of fiber intake per day provides many benefits. These include reduced incidence of type 2 diabetes, stroke, cardiovascular diseases, and colon cancer.
The Dietary Guidelines for Americans suggest that adult males (31-50 years) should consume 30.8 grams of fiber per day. The adult females (31-50 years) should ensure the daily intake of 25 grams of fiber.
Researchers from Washing University School of Medicine investigated which type of fiber provided more benefit to gut bacteria.
The experimental setup
Dr. Jeffrey Gordon explained that fiber is beneficial to the gut. However, it consists of a large number of different compounds.
Moreover, the fiber obtained from different plant sources has different compounds in it. Same is the situation for the fiber obtained from different processed food products.
However, we do not have enough knowledge about the biological significance of different fibers.
Dr. Gordon with his team studied the effect of different fiber on the gut microbiome. They used mice model for this purpose.
They grew the mice in a sterile environment. This is why the mice had no gut microbiome of their own. Later, the team provided the mice with 20 different strains of the common gut bacteria Bacteroids. They isolated these strains from the human gut.
After that, each mouse was given a specific diet that consisted of a base diet and added fiber, for 4 weeks.
The base diet included relatively higher amounts of saturated fat and lower amounts of fruits and vegetables. This diet was typically the reflection of a Western diet that contains less fiber and more fat.
The tea added different type of fiber to each base diet. The fiber was derived from citrus peel, pea protein, apple fiber, rice bran, and others. As a result, the team prepared 144 diet combinations.
The team analyzed the response of all 20 strains to these different types of fiber in all mice.
Effect of different fiber on different strains
They found that 21 diet combinations significantly provided benefit to the given gut microbiome. This enabled the researchers to establish the strain’s specific nutrient harvesting capabilities.
They explained that B.thethiotaomicron population increased in the presence of pea fiber and citrus pectin. On the other hand, B.ovatus proliferated more in the presence of barley bran and barley β-glucan.
Similarly, the other strains of Bacteroids increased particularly in the presence of psyllium, inulin, and maltodextrin.
Researchers told that the pea fiber contains an active constituent- a polysaccharide called arabinan. While in citrus pectin, they found homogalacturonan that led to bacterial growth and proliferation.
The team also observed the interactions between different strains in the presence of fiber. They found that for each fiber, the hierarchical relations between different strains were specific.
The team concluded that by identifying which dietary components the gut bacteria efficiently utilize can help in health promotion.