A new study finds that resveratrol - a chemical found in grape skins and red wine - may protect against cancer, despite the alcohol content of red wine being a risk factor for head and neck cancer.
Scientists have drawn most of their knowledge on the relationship between alcohol and cancer from the study of a disease called Fanconi anemia. This disease affects 1 in 350,000 babies and is characterized by the inability to repair tangles of DNA known as "cross links."
The lack of repair causes damaged DNA to accumulate, which puts the patient at increased risk of developing leukemia and cancers of the head or neck.
Both alcohol-caused cancer and the genetic accelerator of cancer in Fanconi anemia are driven by the same mechanism: partially metabolized alcohol.
In the initial stages of metabolizing alcohol, the body converts alcohol to acetyl aldehyde, before converting it into acetic acid using aldehyde dehydrogenase (ALDH).
However, acetyl aldehyde is a carcinogen and produces DNA cross links, which puts Fanconi anemia patients at higher risk of cancer because they are unable to repair the DNA damage caused by acetyl aldehyde.
If the patient also lacks ALDH, then their risk for cancer is even higher.
Red wine drinkers have 'lowest incidence of alcohol-caused cancer'
"With enough alcohol, the body can get behind and end up with a backlog of acetyl aldehyde," says study author Robert Sclafani, PhD, investigator at the University of Colorado (CU) Cancer Center. He continues:
"Increased exposure to alcohol, loss of the ALDH gene that helps the body process alcohol, and loss of the ability to repair DNA cross links all result in increased cancer risk.
But when you look at epidemiological studies of head and neck cancer, alcohol is a factor, but by alcohol source, the lowest cancer incidence is in people who drank red wine. In red wine, there's something that's blocking the cancer-causing effect of alcohol."
Publishing their findings in the journal Advances in Experimental Medicine and Biology, the CU researchers discuss this protective quality.
Sclafani explains that the more someone drinks, the more DNA damage they accumulate, increasing their cancer risk. However, the resveratrol from the grape skins in red wine eliminates cells with the most DNA damage, which are the ones with the highest likelihood of becoming cancerous.
"Alcohol bombards your genes," he says. "Your body has ways to repair this damage, but with enough alcohol eventually some damage isn't fixed. That's why excessive alcohol use is a factor in head and neck cancer. Now, resveratrol challenges these cells - the ones with unrepaired DNA damage are killed, so they can't go on to cause cancer. Alcohol damages cells and resveratrol kills damaged cells."
Sclafani warns, however, that resveratrol is not a "magic bullet" that cancels out the increased risk of cancer provided by alcohol.
"Because alcohol-related head and neck cancer has a high rate of recurrence, after a cancer has been treated once, you've still got a very high-risk population," he says.
Next, Sclafani and colleagues plan to investigate resveratrol as a preventative treatment for head and neck cancer.
However, senior investigator on that study, Michael Nicholl, assistant professor of surgery at the MU School of Medicine, commented that, "Because of difficulties involved in delivery of adequate amounts of resveratrol to melanoma tumors, the compound is probably not an effective treatment for advanced melanoma at this time."