Hops rich in anti-cancer compounds
that it may help prevent cancer if a method to improve its
absorption in the body can be found.
The anti-cancer activity of xanthohumol was first discovered around 10 years ago by a team at Oregon State University in the US.
But although some brewers are now marketing products enriched in the compound, such as Germany's Xam, the US researchers say beer is unlikely to offer any anti-cancer benefits.
Fred Stevens, based at Oregon's Linus Pauling Institute, told NutraIngredients.com: "Even with higher levels of xanthuomol in beer it is very hard to get the levels we tested in cell cultures into the bloodstream."
"Absorption is very limited and even if it was all absorbed, there is very active metabolism. The xanthuomol is mostly glucaronated."
Nevertheless, Stevens believes the findings are promising enough to merit further research, and also to look at different methods of consumption.
"If you put the compound in a capsule, that's a whole different story," he said.
A number of studies in cell culture and in animal models have demonstrated the flavonoid's ability to kill cancer cells, including a recent study presented at the AACR meeting in Baltimore earlier this month.
The poster presentation described how xanthohumol killed prostate cancer in cells and animal models through apoptosis.
In previous work looking at breast, ovarian and colon cancer cells, the researchers have also identified other mechanisms of anti-cancer action. Xanthohumol, and other related flavonoids in hops, appear to inhibit the family of enzymes commonly called cytochromes P450 that can activate the cancer process.
It also induces activity in a 'quinone reductase' process that helps the body detoxify carcinogens.
Other research groups have picked up on the research and are looking further at the compound.
"The published literature and research on its properties are just exploding at this point, and there's a great deal of interest," added Stevens.
It is thought that hops might be produced or genetically engineered to have higher levels of xanthohumol, specifically to take advantage of its anti-cancer properties.
Some beers already have higher levels of these compounds than others. Lager and pilsner beers have fairly low levels of these compounds, but some porter, stout and ale brews have much higher levels.
Ideally, researchers say, cancer chemoprevention is targeted at theearly stages of cancer development and prevented by long-term exposureto non-toxic nutrients, food supplements or drugs that prevent theformation of cancers.
With its broad spectrum activity, presence in food products, and ability to inhibit cancer at low concentrations, xanthohumol might be a good candidate for that list.
Meanwhile the US government's National Institutes of Health is funding a study to test the potential for another hops compound, structurally very similar but with oestrogenic properties, to help menopause symptoms.
