Acetaldehyde In Alcohol: 'Hangover Chemical' May Be Overlooked Risk Factor For Cancer

New evidence by researchers at the Centre for Addiction and Mental Health (CAMH) and researchers in Germany shows that drinking alcohol is the greatest risk factor for acetaldehyde-related cancer. Heavy drinkers may be at increased risk due to exposure from multiple sources.Acetaldehyde is ubiquitous in daily life in Ontario. Widely present in the environment, it is inhaled from the air and tobacco smoke, ingested from alcohol and foods, and produced in the human body during the metabolism of alcoholic beverages. Research indicates that this organic chemical plays a significant role in the development of certain types of cancers (especially of the upper digestive tract), and it is currently classified as possibly carcinogenic by the International Agency for Research on Cancer of the World Health Organization.

New research from CAMH in Toronto and the Chemical and Veterinary Investigation Laboratory Karlsruhe (CVUA) in Germany recently provided the necessary methodology for calculating the risk for the ingestion of alcoholic beverages.

The team found that risk from ingesting acetaldehyde via alcoholic beverages alone may exceed usual safety limits for heavy drinkers. Their risk assessment study found that the average exposure to acetaldehyde from alcoholic beverages resulted in a life-time cancer risk of 7.6/10,000, with higher risk scenarios (e.g. contaminations in unrecorded alcohol) in the range of 1 in 1,000. As such, the life-time cancer risks for acetaldehyde from ingestion of alcoholic beverages greatly exceed the usual limits for cancer risks from the environment.

The research team noted, however, that this risk is compounded by the addition of acetaldehyde exposure from different sources. "The problem with acetaldehyde has been that although it has been recognized as toxic by Health Canada some years ago, most risk assessments to date were based on one source of exposure only" explained Dr. Jürgen Rehm, the lead scientist of the Toronto group and head of the Public Health and Regulatory Policies section at CAMH. "This has led to a negligence of the overall risk."

For example, in Toronto, even though there are limits for air exposure of acetaldehyde set by the responsible Public Health agency, these limits have been surpassed in the past. Alone, the risks associated with surpassing limits of acetaldehyde from the air may not yet be alarming, but for heavy drinkers and smokers, it adds to the acetaldehyde levels already received from these sources. This overall risk then surpasses established safety limits.

"Their risk assessment of acetaldehyde present as a congener in alcoholic beverages touches the tip of the iceberg," according to a Commentary on the CAMH/CVUA study in the journal Addiction.

New Lab Evidence Suggests Preventive Effect Of Herbal Supplement In Prostate Cancer

DHEA is a natural circulating hormone and the body's production of it decreases with age. Men take DHEA as an over-the-counter supplement because it has been suggested that DHEA can reverse aging or have anabolic effects since it can be metabolized in the body to androgens. Increased consumption of dietary isoflavones is associated with a decreased risk of prostate cancer.Red clover (Trifolium pretense) is one source of isoflavones. Both supplements may have hormonal effects in the prostate and little is known about the safety of these supplements.

In a recent report in Cancer Prevention Research, a journal of the American Association for Cancer Research, researchers report that DHEA levels can be manipulated in cells in the laboratory to understand its effects.

Julia Arnold, Ph.D., a staff scientist at the National Center for Complementary and Alternative Medicine (NCCAM) at the National Institutes of Health, said more research is necessary in an environment where men and women concerned about health problems tend to self-prescribe based on information they find on the Internet.

Towards this end, the NCCAM laboratory is studying signaling between human prostate cancer cells and their supporting stromal cells as they grow together in laboratory culture. "DHEA effects in the prostate tissues may depend on how these two cells types 'talk to each other' and further, it may be potentially harmful in tissues containing inflammation or with early cancer lesions because the cells can induce DHEA to become more androgenic," said Arnold.

Combining DHEA with transforming growth factor beta-1 increased testosterone production in the stromal cells and prostate specific antigen protein secretion two to four-fold and gene expression up to 50-fold in the cancer cells. When these cell cultures were treated with red clover isoflavones, the androgenic effects of DHEA were reversed.

"Something is happening in the prostate tissue microenvironment that is illustrating a potential cancer prevention effect from this supplement," said Arnold.

Red clover isoflavones may modify androgenic effects in the prostate but much more work in the laboratory and clinic is needed to validate these effects.

This sort of laboratory manipulation will allow scientists to understand the basic prostate biology as well as learn cellular and molecular mechanisms of over-the-counter supplements and other botanical or herbal agents. Arnold said NCCAM will continue to study DHEA with other supplements to determine any cancer preventive effects.

Catching The Common Cold Virus Genome

A new study by Brigham Young University researchers on the virus behind nearly half of all cold infections explains how and where evolution occurs in the rhinovirus genome and what this means for possible vaccines."There are a lot of different approaches to treating the cold, none of which seem to be effective," said Keith Crandall, professor of biology and co-author of the study. "This is partly because we haven't spent a lot of time studying the virus and its history to see how it's responding to the human immune system and drugs."

The BYU team studied genomic sequences available online and used computer algorithms to estimate how the rhinovirus is related to other viruses.

According to Nicole Lewis-Rogers, a postdoctoral fellow in the Biology Department and lead author on the study, the rhinovirus is similar to the polio virus, whose vaccine was announced in 1955. But while the polio virus has just three subspecies, the rhinovirus has more than 100 subspecies, which continually evolve.

"These viruses could be under the same constraints and yet change differently," Lewis-Rogers said. "That's why it is so hard to create a vaccine."

Through a computer program developed at BYU, Lewis-Rogers' team was able to identify the parts of the virus genome that enable resistance to drugs and the human immune system.

The immune system does a good job of recognizing viral contaminants and getting rid of them, as do new drugs, but the rhinovirus has responded to these defenses by changing its genome so that it is not so easily recognized.

"The virus is evolving solutions against the immune system and drugs," Crandall said. "The more we can learn about how the virus evolves solutions, the better we can rid the body of these infections."

Understanding where change occurs in the virus genome will help virologists who work to design drugs that target the rhinovirus.

"If you've got 10,000 bits of information, this narrows it down to a handful," Lewis-Rogers said. "Here is where you can start looking."

Lewis-Rogers and Crandall hope scientists will use these insights to build better drugs to combat the virus in the most effective way.

The study is reported in the April issue of the journal Molecular Biology and Evolution. BYU undergraduate Matthew Bendall is also a co-author on the study, which was funded by the USDA. Bendall will next pursue a master's in bioinformatics at BYU.