Should we be wary of eating red meat? Taken at face value, a new study suggests that might be a good idea -- but a more careful consideration does not.
A report in the March 23 issue of the Archives of Internal Medicine describes a very large study -- over half a million people initially aged fifty-one to seventy-one years -- who reported their diets at the study's outset and were then followed for ten years. Over 300,000 men and over 200,000 women participated in the study. During the follow-up period approximately 48,000 men and 23,000 women died.
The researchers tabulated the numbers who died from cancer, cardiovascular disease, injuries and sudden deaths, and from all other causes. When they divided the subjects according to how much red, processed, and white meat they reported eating at baseline, the researchers found some increases in the risk of death in those reporting the highest intake of red and processed meats compared to those reporting the lowest intake. Conversely, the highest intake of white meat -- chicken, turkey, and fish in various forms -- was associated with a reduced risk of dying of cancer and other causes of death.
While the sheer size of the study means it should not be taken lightly, there are reasons to look askance at some of the scary stories now making the rounds that are not really supported by the science.
•First, participants in the study didn't actually measure the amount of foods they ate. While this may not be very important for foods and beverages that are purchased in discrete quantities (e.g., a fast food hamburger or a bottle of soft drink), meat can be purchased and consumed in a wide variety of forms and sizes. Thus, the accuracy of the data depends on how well participants can estimate the quantities of the various foods they consumed, as well as how accurate they are when they recall how often they ate or drank particular items. Neither of these estimates is the most reliable indicator of actual consumption.
•Second, intake of various food items was ascertained only once -- at the start of the study. There is no information about whether or not people changed their diets over the course of the follow-up period -- this may well have had an impact on any disease-diet relationships.
•Third, the increases in risk did not reach the levels that would make most epidemiologists sit up and take notice -- a relative risk of 2 (a 100% increase) or greater. In fact, the increased risk of all deaths in the men in the highest group of red meat intake was 31% and for cancer was 22%. For women, the corresponding increases were 36 and 20%.
As the authors concluded, the highest intakes of red and processed meats were associated with "a modest increase in risk of total mortality, cancer, and CVD mortality in both men and women."
At best, this study supports the oft-repeated advice that a healthful diet should be based on moderation, variety, and balance. What's so new about that?