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Cancer development has degree of randomness

Dear Dr. Roach: I have lost two cousins in the past three years (a married couple) who both ate a lot of red/rare meat most of their lives. He got Parkinson’s first, and she got cancer throughout her body and passed away yesterday. I can’t help but wonder if their almost-daily consumption of red meat had anything to do with their demise. – J.V.H.

Answer: I am sorry to hear about your cousins.

“Cancer” is a large and diverse group of related diseases. The underlying cause is not always clear, and although there often are genetic or behavioral risks, development of cancer has some degree of randomness, such that blaming an individual’s cancer on some behavior is likely to oversimplify the situation, and unlikely to be welcome, in any event.

Smoking dramatically increases the risk of many cancers, whereas the effect of red meat is modest. Red meat intake has been shown, in multiple studies, to increase the risk of colon and lung cancers and, in one recent study, to increase risk of cancers of the esophagus and lung. The group that had least red meat intake (about five servings per week) had about a 20 percent reduced risk compared with the group eating the highest amount of red meat. This doesn’t mean that red meat causes cancer, as those who eat little meat often have other healthy behaviors that may reduce cancer risk and which the authors didn’t recognize.

A 2003 study on Parkinson’s disease showed that reducing meat intake improved some function in people with Parkinson’s. However, I can’t say that meat intake is causal in any way for Parkinson’s disease. I can say that overall, less red meat intake is associated with a variety of improved health outcomes, especially vascular disease, but cancer and kidney disease as well, even though the magnitude is small.

Dear Dr. Roach: I often read advice by health professionals on the advantage of the Mediterranean-style diet for warding off various ailments, as you recently wrote in a newspaper article relative to dementia. These recommendations seem to imply that the people who live around the Mediterranean Sea, on average, have a longer, healthier life than those people who live in Northern Europe: Germany, Sweden, Denmark, Great Britain and others, based on their local diets. Are there actual statistics that back this up? – R.

Answer: Comparing overall mortality rates of different cultures and using that information to infer relative benefits of eating patterns is fraught with peril, scientifically speaking. A country-to-country comparison has far too many uncontrolled variables to make reliable conclusions.

The reason I and many other health professionals have recommended a Mediterranean-style diet is that there was a very well-done interventional study randomizing participants to a diet consisting of high amounts of olive oil, nuts, fresh fruits, vegetables, seafood (especially fatty fish), legumes, sofrito (a tomato and vegetable sauce), white meat and optional wine. The diet also recommended low amounts of soda, commercial baked goods, spread fats like butter, and red and processed meats. Compared with a control group that was recommended a low-fat diet, participants in the Mediterranean-diet group had a lower rate of the combined endpoint heart attack, stroke or death from cardiovascular causes. A randomized interventional study like this provides strong evidence that the recommended diet is superior to the diet consumed by the control group. It is impossible to tell whether it was some individual component that was responsible for the benefit, or whether it was a combination of what the participants were and weren’t eating that provided the observed benefit.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.