Diet high in soluble fibre may combat obesity

Eating more foods high in soluble fibre - found in oat bran, nuts, lentils, peas, and some fruits and vegetables, may help prevent metabolic disease and obesity, a new study has found.
Researchers at Georgia State University in US found that a diet missing soluble fibre promotes inflammation in the intestines and poor gut health, leading to weight gain in mice.
But incorporating soluble fibre back into the diet can restore gut health.
The study examined the effects of diets varying in amounts of soluble and insoluble fibres, protein and fat on the structure of the intestines, fat accumulation and weight gain in mice.

They found that mice on a diet lacking soluble fibre gained weight and had more fat compared with mice on a diet that included soluble fibre.
The intestines of mice on the soluble fibre-deficient diet were also shorter and had thinner walls. These structural changes were observed within two days after starting the diet.

The researchers also found that introducing soluble fibre into the diet restored gut structure. Supplementing with soluble fibre inulin restored the intestinal structure in mice on the soluble fibre-deficient diet.
Mice that received cellulose, an insoluble fibre, however, did not show improvements.
Moreover, in mice fed a high-fat diet, switching the type of fibre from insoluble to soluble protected the mice from the fat accumulation and intestinal wasting that occurs with excess fat consumption.

The data suggest a difference in health benefits between soluble and insoluble dietary fibres, the researchers said.
Improvements in gut structure with soluble fibre were due to changes in the gut microbiota and the gut microbiota's production of molecules called short chain fatty acids, which are used as fuel by intestinal cells and have anti-inflammatory properties, researchers said.
Mice consuming a soluble fibre-deficient diet had lower levels of short chain fatty acids, and introducing soluble fibre into their diet boosted their levels.
Supplementing the soluble fibre-deficient diet with short chain fatty acids had similar effects as inulin supplementation, although not to the same extent.

Inulin supplementation increased the size of the intestines in normal mice but not in mice with no gut microbiota, supporting that the gut microbiota is involved in the intestinal health effects of soluble fibre.
According to the researchers, the data support that soluble fibre promotes gut health by encouraging the gut microbiota to produce short chain fatty acids.
"If our observations were to prove applicable to humans, it would suggest that encouraging consumption of foods with high soluble fibre content may be a means to combat the epidemic of metabolic disease," the researchers said.
The study was published in the American Journal of Physiology - Gastrointestinal and Liver Physiology.