Sugar disrupts microbiome contributing to inflammation and obesity

Combining a high sugar and high fat diet can lead to a variety of health problems. This is certainly not breaking news. However, recent studies have found that changes in the gut microbiome can have negative effects on our overall health. Diets high in sugar can contribute to metabolic conditions such as insulin resistance and obesity. But what role does our microbiome play in all of these?

World of Bacteria

So what exactly is our microbiome? Well, the gut microbiome consists of trillions of bacterium. These bacteria are both helpful and potentially harmful. Most are symbiotic bacteria (both the body and microbiota benefit) and there are smaller numbers of pathogenic bacteria (promotes disease). In a healthy body, these microbiota coexist without any problems. However, when there is a disturbance in the balance, brought on by certain diets, infections, or prolonged use of antibiotics (among other reasons), dysbiosis occurs. Dysbiosis is a disruption of the microbiome resulting in an imbalance of microbiota, which changes their function as it relates to metabolic processes and total volume. As a result, the body becomes more susceptible to disease.

New Findings

A recent study published in the Cell centered on what impact a high-fat and high-sugar diet had on the microbiome of mice. More specifically, they wanted to examine the behavior of a specific kind of immune cell called Th17 (reference image above). These immune cells are a subset of an immune T-cell that helps protect the gut from certain pathogenic bacteria. Low levels of Th17 cells have been associated with metabolic and inflammatory conditions. These immune cells produce molecules that slow the absorption of pathogenic lipids in the intestines and also decreases intestinal inflammation.

When the mice were fed high-fat and high-sugar diets, they quickly developed signs of metabolic disease such as weight gain, glucose intolerance, and elevated inflammatory markers. Additionally, they saw rapid reductions in Th17 cells. The decrease in these cells were clearly diet-induced and bacteria responsible for promoting Th17 cells were replaced with other gut bacteria. It was sugar that particularly seemed to increase populations of harmful gut bacteria rather than fat. In fact, researchers found that as long as the mice retained high levels of gut bacteria known to induce Th17, a fatty diet did not lead to negative metabolic effects. They found this out by feeding a high-fat but sugar-free diet to the mice. The microbiome retained the intestinal Th17 cells and helped protect them from developing pre-diabetes and obesity even though the same number of calories were consumed.

The image below shows the response of Th17 cells to SFB, a friendly bacteria, and C. rodentium, which is a pathogen. Note the aerobic glycolyis; the breakdown of sugar.

Final Thoughts

So what can we gather from the results? Well first, remember this study was done on mice. Although humans and mice share similarities being part of the animal kingdom, they are very much different. Now there are studies that highlight similar outcomes with high-sugar diets (i.e. inflammation, microbiome disruption) but this study specifically looked at changes in Th17 cells due to sugar intake and how that led to metabolic problems.

The point is, your nutrition plays a major role in regulating your overall health and immune system. It can literally change the path by which your health takes. So what you consume can either help or hurt you. Choose what you eat wisely. However, it’s safe to say that the Western diet (largely high fat and high sugar) is not doing your gut any favors.