Bugs in Our Guts and How They Affect Obesity

We are what we eat, and more importantly, what we absorb from food, through our intestines or gut.

The gut is home to trillions of useful microorganisms which are important for the body’s immunity. Different species of bacteria inhabiting the guts have different effects on appetite and metabolism.

Bacteria in the gut; Source

Pathogenic Biofilms

The intestinal flora form a micro-colony of organisms called biofilm, which is a combination of microbes, mucous, and immune system molecules. The microbes in the biofilm are nourished by the polysaccharides coating on the intestinal surfaces and, in turn, help to break down the food we eat. They also protect bacteria in the biofilm from the immune system, antibiotics, and other bacterial species.

Types of Gut Flora and Obesity

It has been established that obese people have different proportions of micro floral bacteria than lean people. Their micro floral bacteria extract more calories from food.

The gut microbiota of obese mice has been shown to have significantly more of a certain type of bacteria called Firmicutes and fewer of another kind called Bacteroidetes. Obese people have a greater proportion of micro flora from Firmicutes, which includes many of the Baccili and Clostridia. Lean people show lower proportions of Firmicutes.

How the microbes in the Intestines Affect the Body’s Metabolism

The bacteria inhabiting the digestive tract affect the ability to extract energy from food. This ability comes from the protein structure called Toll-like receptor (TLR) 5 that cells in the intestinal lining sprout on their surface. TLR5 acts as a traffic cop for controlling the mass of pathogens living in the intestine by recognizing and binding to the whiplike flagella that bacteria use to move around.

As part of the innate immune system, TLR5 helps to recognize microbes and determine the types of bacteria populating the gut. Without TLR5 , the normally harmless gut bacteria tend to overflourish and expand in number.

TLR5 and Metabolism

Changes in the gut flora can increase the rate at which we absorb fatty acids and carbohydrates, and increase the storage of calories as fat. This means that someone with bad gut flora could eat the same amount of food as someone with a healthy gut, but extract more calories from it and become obese. Bad bugs can increase the production of insulin leading to metabolic syndrome/diabetes, and cause inflammation of the hypothalamus that controls appetite and weight.

To explore the role of intestinal bacteria (microbiota) and TLR5 in developing metabolic syndrome, scientists generated mice that do not produce TLR5 protein. They had too much bad bacteria in their guts which caused a low-grade inflammation in the mice. When the TLR5-deficient mice were given unrestricted diets, they ate 10% more than normal mice, and that even when their food was limited, they were still less sensitive to insulin than their normal counterparts and developed type 2 diabetes and fatty livers. So the scientists believe that gut microbiota determine whether your body will store the food you eat as extra pounds.

The most interesting part of this study is that obesity and diabetes could be introduced from one group of mice to the other simply by transferring their gut flora.

Conclusion

The health and composition of your intestinal micro flora are essential to be lean and fit for life.

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