Hops compounds change gut microbiome, help with metabolic syndrome

Compounds from hops may combat metabolic syndrome by changing the gut microbiome and altering the metabolism of acids produced in the liver, according to a new study by researchers at Oregon State University and published in the journal Molecular Nutrition and Food Research.

The study builds on earlier research that found xanthohumol (XN) and two hydrogenated derivatives, DXN and TXN, can likely improve cognitive and other functions in people with metabolic syndrome. People are considered to have metabolic syndrome if they have at least two of the following conditions: abdominal obesity, high blood pressure, high blood sugar, low levels of "good" cholesterol, and high levels of triglycerides.

A diet high in saturated fat and refined sugars causes chronic low-grade inflammation that contributes to the development of metabolic syndrome. The syndrome is associated with cognitive dysfunction and dementia as well as being a major risk factor for cardiovascular disease and type 2 diabetes.

In earlier studies, testing in a mouse model showed that XN, DXN, and TXN improve glucose intolerance, insulin resistance and sensitivity to leptin, a hormone that tells you to feel full when you have eaten enough and helps regulate energy expenditure. All these changes are thought to be beneficial in the fight against metabolic syndrome, the researchers said.

In the most recent research, laboratory animals were given a high-fat diet exclusively, or a high-fat diet that included XN, TXN, or DXN. Scientists then measured the compounds' effects on bile acids, bile is a fluid produced by the liver that helps with the digestion of fats, tissue inflammation, and gut microbiome composition.

The results showed that each of the hops compounds decreased the amount and diversity of microbes, reduced inflammation and changed bile acid metabolism. Additionally, there was a reduction in secondary bile acid production and an increase of conjugated bile acids, which are indicators of improved energy metabolism, glucose metabolism, and cholesterol metabolism, the researchers said.

Researchers note that further research will try to determine what the compounds are doing directly to the body in addition to what they're doing through the gut microbiota. 

"Changes in gut microbiota and bile acid metabolism seem to explain at least partially why XN and its derivatives lead to improvements in obesity and other aspects of metabolic syndrome," said Adrian Gombart, PhD, the study's corresponding author and professor of biochemistry and biophysics in the College of Science and a principal investigator at the university’s Linus Pauling Institute. "But this is not necessarily cause and effect—we need to know which changes to the microbiota are beneficial."