Red meat and cancer: dumbing down the science

At this morning’s session on Diet and Cancer, Dr. Marji McCullough gave an epidemilogist’s-eye view of the relationship between cancer and diet. Her main point was that focusing on overall dietary patterns (such as higher fruit and vegetable intake) rather than individual nutrients and foods (such as broccoli sprouts or soy) appears to be the most effective way to reduce cancer risk.

Throughout her talk, she was careful to point out the limitations of the research and how hard it is to collect and intepret data in the extremely messy experimental model known as “free living humans.”  So I was a little disappointed to hear her single out “red and processed meats” as one of the only food groups for which there is consistent evidence of a link with cancer.

First of all, it always irritates me to hear “red and processed meat” discussed as a single food group. My friends, there is a world of difference between a hot dog and a bison steak.

Cured meats and cancer

There does appear to be a link between cancer and high consumption of processed (i.e. cured) meats like hot dogs, sausages, salami, and cold cuts–most likely due to nitroasamines formed from the nitrates used to cure these meats. Incidentally, nitrosamines are deactivated by vitamin C and the link between cured meat consumption and cancer risk disappears in those who eat a lot of vegetables. That’s right: Those who eat the most cured meats but also the most vegetables have no increased risk of cancer.

But, I digress.  Back to (uncured) red meat.

Cooking methods and cancer

McCullough suggested that red meat consumption might contribute to cancer because heat-heat cooking methods (such as grilling) create harmful compounds. Hang on a minute. Maybe the problem isn’t red meat. Maybe the problem is charred meat.   After the talk, I had a chance to chat with Dr. McCullough and she admitted that from the existing data, most of which was collected 20 and 30 years ago, researchers can’t really distinguish between the type of meat and how it was cooked. Nor can they separate Big Macs from flank steak…nor beef from bison…nor grass-fed from corn-fed. It’s all just “red meat.” And what kind of red meat were Americans eating most of in the 80s and 90s?

Dumbing down the science?

For folks who eat most of their red meat in the form of char-grilled, high-fat, fast-food burgers, telling them that they can cut their cancer risk by cutting back on “red meat” may be good public health policy.  But in over-simplifying the prescription this way, we may be throwing the baby out with the bathwater.

Is there any evidence to suggest that lean, grass-fed red meat, prepared in a way that minimizes formation of HCAs and PAHs increases your risk of cancer? No, there is not. (Click for tips on how to reduce harmful compounds)  In fact, compared with poultry, red meat is higher in monounsaturated fats and lower in omega-6 fats–two qualities that red meat has in common with the cancer-protective Mediterranean diet pattern.

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