By: Eric Mittenthal
It is rare that I sit in a session at a conference and am riveted by the entire presentation. But that was the case when David Klurfeld, Ph.D., USDA’s National Program Leader for Human Nutrition in the Agricultural Research Service, spoke at our recent Meat Industry Summit. Dr. Klurfeld is not only a leading nutrition researcher, but he also served as one of the experts on the International Agency for Research on Cancer (IARC) review of red and processed meats in 2015.
It is notable that Dr. Klurfeld was one of the panelists who voted against designating processed meats as carcinogenic and red meat as probably carcinogenic, and he was not the only one. Of the 22 experts on the panel, several disagreed with the final designations. As Dr. Klurfeld explained, the primary reason for their disagreement was a lack of strong science suggesting that either processed or red meat are carcinogenic. While media regularly claims that IARC reviewed 800 studies in connection with their decision, the fact is that most of those did not provide much value toward a conclusion. Instead there were a limited number of epidemiological studies which were considered in reaching the final decision…just 18 studies on processed meat, 12 of which suggested a correlation with cancer and 14 studies on red meat, seven of which suggested a correlation (meaning seven did not).
As the Meat Institute said when the report was released in 2015, after an Institute official observed the IARC meeting, “It was clear sitting in the IARC meeting that many of the panelists were aiming for a specific result despite old, weak, inconsistent, self-reported intake data. They tortured the data to ensure a specific outcome.” Dr. Klurfeld highlighted a perfect example of this: on the night before the final decision to categorize red and processed meats, experts were given a six inch thick binder of studies to review. It seems reckless at best to make such a substantial public health claim when given such a limited time frame for scientific review. This may help further explain why the categorization was far from unanimous.
The weakness of the research considered is the other, more important reason to question IARC’s classifications. A great deal has been written about the limitations of self-reported intake studies that ask people to recall what they ate during a certain time period, which is primarily what IARC’s conclusions are based on. As Dr. Klurfeld pointed out to us, random correlations can be found in many completely unrelated circumstances—did you know that the divorce rate in Maine almost exactly correlates with consumption of margarine? But look even deeper and the weak data on red and processed meat and cancer is apparent. Whereas studies showed that the relative risk for smoking and lung cancer was between 10-30 — meaning your risk of lung cancer is 10-30 times higher if you smoke — the relative risk for processed meats as reported by IARC is 1.18 per 50 grams a day. Put another way, the risk of getting colon cancer for vegetarians is 4.5 percent. The risk calculated by IARC of getting colon cancer if you eat 50g of processed meat every single day (a hot dog a day) is 5.3 percent. Other studies have found no dose response patterns between meat intake and cancer incidence, which would suggest that the limited correlations don’t offer much real world applicability.
The other element that IARC and other research completely ignores is the nutrition benefits of red and processed meat. Consider the amount of nutrients you get from a portion of lean beef tenderloin (see graphic below). Not only are you meeting half of the daily protein recommendation, but it also delivers significant portions of iron, zinc, selenium, Vitamin B12 and Niacin, all at a limited calorie intake. Processed products are not substantially different. They may incorporate some additional ingredients but their basic nutrition is very similar. The number of different products on the marketplace allow people to choose the options that fit their dietary needs whether they be low in calories, fat or sodium. As the World Health Organization pointed out just days after IARC published its initial findings, “The latest IARC review does not ask people to stop eating processed meats.”
When you balance the nutrition benefits of meat with its limited risks, it is clear to Dr. Klurfeld that meat has a beneficial role in the diet and he’s not alone. Despite much of the rhetoric, many other researchers have reached the same conclusions including those who develop the U.S. Dietary Guidelines for Americans. The next time you hear otherwise, take a minute and consider what the science actually shows. For links to more research about the benefits of meat and poultry in the diet, visit www.meatpoultrynutrition.org