The health benefits of a polyphenol found in hops is dependent upon its interactions with intestinal microorganisms, according to new research.
Xanthohumol (XN) is a flavonoid from the hops plant (Humulus lupulus) exerting antioxidant, anti-inflammatory, anti-hyperglycemic, and anti-hyperlipidemic activities. Because XN also acts as a prebiotic for intestinal microbiota and can alter the gut microbial composition in conjunction with its bacterial metabolites, researchers wanted to see whether XN requires gut microbiota to mediate its benefits.
Twenty scientists from Oregon State and Carlson College of Veterinary Medicine compared the glucose metabolism effects of XN on normal mice with gut microbiota and those engineered to be germ free.
The research team fed the normal and germ-free male mice either a low-fat diet (10% fat derived calories), a high-fat diet (60% fat derived calories), or a high-fat diet supplemented with XN for 10 weeks, and measured parameters of glucose and lipid metabolism.
In the normal mice, the researchers discovered XN supplementation decreased plasma insulin concentrations and improved homeostatic model assessment of insulin resistance, a method of assessing beta-cell function in insulin resistance. In the germ-free mice, XN supplementation failed to improve these outcomes. Fecal sample 16S rRNA gene sequencing analysis suggested XN supplementation changed microbial composition and dramatically altered functional capacity of the intestinal microbiota.
The research also revealed that intestinal microbiota metabolizes XN into bioactive compounds, including dihydroxanthohumol, an anti-obesogenic compound with improved bioavailability.
An “important interaction”
"There is an important interaction between the compound and the microbes in the gut that provides the benefits we see in our studies with mice,” explained lead researcher Adrian Gombart, Associate Professor, Department of Biochemistry and Biophysics at Oregon State University. "We found that only the conventional mice with XN supplementation showed improved glucose metabolism and that XN increased the relative abundance of three bacteria, Akkermansia muciniphila, Parabacteroides goldsteinii and Alistipes finegoldii.”
Gombart added that the study yielded some evidence that those three microbes are at least partially responsible for the health benefits associated with XN, but said he can’t rule out that the entire microbial community may be behind the benefits too.
The team concluded that the results warrant future metagenomic studies, which will provide insight into complex microbe-microbe interactions, and diet-host-microbiota interactions.
Source: Molecular Nutrition & Food Research
2021 DOI: 10.1002/mnfr.202100389
“Xanthohumol Requires the Intestinal Microbiota to Improve Glucose Metabolism in Diet‐Induced Obese Mice”
Authors: I. Logan et al.