Last week, Fox News reported on the possibility of developing treatments for cancer and diabetes from an ingredient in beer: humulones, the chemicals which give hops their bitter flavor. The story has been making the rounds since January 28, when a paper published in Angewandete Chemie International Edition was covered in a well-researched press release from the University of Washington.
Unfortunately, the paper did not actually add to the small body of evidence for hop health benefits. Like many alcoholic beverages, beer may have beneficial health effects for some when used in moderation, but it is better at causing cancer than curing it.
The original paper primarily concerned the structure of several humulones and isohumulones produced during the brewing of beer, demonstrating that their structures are actually mirror images of what had been believed for the past 60 years. The researchers used X-ray crystallography, a difficult but extremely reliable method, to conclude that Horeau's method of partial decoupling and the Cotton Effect in optical rotary dispersion had misled previous investigators. This raises some worry for biochemists that the structures of other compounds might also be incorrect. It is also very interesting to beer manufacturers, who now isomerize hop humolones separately from the brew to control flavor more precisely. They will find the process easier now that they know what they are really making.
What interested the news organizations was based on just a few sentences from the paper summarizing previously published results: "Claims that beer and the bittering acids found in beer are beneficial when consumed in moderation have accumulated over time, including positive effects on diabetes, (14 15 16) forms of cancer, (17 18 19 20) and inflammation, (21) and even linking reduced iso-α-acid derivatives to weight loss. (22 23 24) Some of these derivatives affect one illness (21 25 26 27 28) whereas others, differing only in the configuration of carbon atoms 4 and 5 of the iso-α-acids (Scheme 1), are ineffective. (29)"
A few of these sources cited above seem of dubious relevance — reference 16 is a very small study of whiskey drinkers, and some of the later references on general theory of bioavailability. Most studied effects in vitro or in mice fed a diet of up to 4% freeze dried beer.
There is fair reason to be skeptical, because only about 1 out of 4 basic research studies holds up when pharmaceutical companies try to use them to develop new drugs, perhaps due to poor design, difficulty, or competitive haste in publishing. Here, of the first 11 references, six were associated with the Kirin Brewery (which conducted the crystallography research) and two were company-funded studies of a particular brand of hops extract — META060 by Metagenics, which might lead a reader to be skeptical of their neutrality. Maybe the very hopeful reduction in blood sugar in patients given a hops supplement (ref 14) was only a random fluke, as it was only a 10% reduction in a group of 10 patients, with nearly as much a decrease observed in the placebo group. Such studies are called pilot studies for a reason: because more research is needed.
Nonetheless, the ideas proposed do make some sense. A common thread appears be related to the handling of fatty acids, which can be converted to proinflammatory factors like prostaglandin E2 and affect PPARs, and therefore colon cancer and obesity. Hops certainly have a long history of traditional use, and a fine pedigree for alternative medicine as the nearest known botanical cousins of cannabis. Humulones have no similarity to cannabinoids, but the plants do share some terpene constituents like limonene and myrcene, which may provide a sedative or analgesic effect. Like many plant species, hops may indeed prove fertile ground to prospect for new therapeutic drugs, and these studies have identified some specific effects to look for.
So far, these effects are dwarfed by the overall impact of alcoholic beverages, which may actually reduce mortality through protective cardiovascular effects when used by older people and in moderation. They also seem to reduce men's risk of coming down with type II diabetes when used frequently, regardless of quantity consumed; unfortunately, for those with diabetes, they can pose some problems.
However, in accord with previous evidence, a NIDA-supported study published this month estimated that alcohol causes 3.5% of American cancer deaths (20,000 people), and the authors could not identify a safe level for consumption. For a drug whose use does not always remain voluntary or moderate, the benefits might not be worth the risks.