High-fibre diet could prevent obesity

High-fibre diets have long been hailed as the solution to a number of health issues, but new research reinforces this theory. Dietary fibre that promotes ‘good’ bacteria in the colon could prevent obesity, metabolic syndrome and changes in the intestine.

Closely linked to obesity, metabolic syndrome can cause health risks such as increased blood pressure, high blood sugar, excess body fat around the waist and abnormal cholesterol levels. Together, these can lead to heart disease, stroke and diabetes.

Both obesity and metabolic syndrome are linked to alterations in gut microbiota, the complex community of microorganisms that live in the digestive tract.

As the modern consumer turns more towards low-fibre and high-fat processed foods, studies have revealed that the gut microbiota is being destroyed. This type of diet reduces the production of epithelial cells lining the intestine and causes gut bacteria to invade intestinal epithelial cells. By doing this, an individual is more likely to experience a chronic inflammatory disease such as metabolic syndrome.

Researchers from Georgia State University looked at how diet impacted mice’s health over a period of four weeks. They were fed with either a grain-based rodent chow, a high-fat diet (with 5% cellulose as a source of fibre) or a high-fat diet supplemented with fibre (either fermentable inulin fibre or insoluble cellulose fibre).

The diet supplemented with inulin reduced weight gain and obesity, reduced the size of fat cells, significantly lowered cholesterol levels and prevented dysglycemia (abnormal blood sugar levels). Insoluble cellulose fibre, on the other hand, only showed slight reductions in obesity and dysglycemia.

The researchers found that inulin restored gut microbiota levels in mice by increasing the production of epithelial cells and restoring expression of the protein interleukin-22 (IL-22). This prevented gut microbiota from invading epithelial cells and protected against low-grade inflammation and metabolic syndrome.

“We found that manipulating dietary fibre content, particularly by adding fermentable fibre, guards against metabolic syndrome,” explained Dr Andrew Gewirtz, a professor at the Institute for Biomedical Sciences at Georgia State. “This study revealed the specific mechanism used to restore gut health and suppress obesity and metabolic syndrome is the induction of IL-22 expression. These results contribute to the understanding of the mechanisms that underlie diet-induced obesity and offer insight into how fermentable fibres might promote better health.”

However, there continued to be a significant difference in the microbiota levels of the mice fed a high-fat diet compared to those fed a chow diet. It was found that inulin did not restore the microbiota levels of mice fed a chow diet.

Therefore, the study suggests that fermentable fibre can protect against metabolic syndrome. With fatty diets becoming more popular and obesity levels rising, the results underpin the importance of consuming more fruits, vegetables and wholegrains.

The results were published in Cell Host & Microbe.

Image credit: ©iStockphoto.com/Alexey Ivanov