This month the American Dietetic Association (ADA) published a position statement about food and nutrition misinformation. According to a survey run by the ADA, the media including TV, magazines, and newspapers are the leading sources of nutrition information for American consumers. Because of their predominant role, the media can be the source of much nutrition misinformation as well for example by allowing individuals or groups with hidden agendas to promote their particular views under the guise of presenting balanced, science-based nutrition information.
One particularly egregious example is the dogged attack on foods of animal origin presented by the self-styled "consumer advocacy" group, Physicians' Committee for Responsible Medicine, or PCRM. The name of the group implies that its membership is made up primarily, if not totally, of physicians, and that therefore its pronouncements on health, science, and nutrition topics should be considered to have a special imprimatur. This is simply not true.
The Center for Consumer Freedom (CCF) (www.consumerfreedom.com) states that only ten percent of PCRM's members are actually M.D.s. CCF also cites evidence about the close philosophical and financial links between PCRM and People for the Ethical Treatment of Animals (PETA), which is a well-known animal rights group. While PETA promotes its animal rights agenda in a forthright, if often raucous, manner, PCRM is more subtle. Its strategy is to impugn the value of animal research and of foods of animal origin, using human health as its pretext.
The American Medical Association (AMA), whose members really are all doctors, has issued resolutions criticizing PCRM's claim to be a responsible medical mouthpiece. One such resolution stated in part, "Our AMA registers strong objections to the Physicians' Committee for Responsible Medicine for ...misrepresenting the critical role animals play in research and teaching..." (www.ama-assn.org).
When it comes to food issues, PCRM is no less misleading. Not only do they say that milk and dairy products don't help build bone strength, they claim that such foods cause a host of diseases, ranging from osteoporosis and asthma to diabetes and even breast and prostate cancer. When questioned about such allegations, the group will point to one or another published study that they state supports their position. They have even posted a longer analysis on their website (www.pcrm.org) purporting to show that numerous studies have found a likely causal link between dairy consumption and prostate cancer. But the truth is otherwise.
In that analysis, PCRM president, Dr. Neal Barnard, examines the results of 23 epidemiologic studies that evaluated the possibility of a link between dairy consumption and prostate cancer. He noted that 11 of the 23 found significant associations between dairy and cancer. But he omits something important: statistical significance is not necessarily the same as biological significance.
When epidemiologists report on their data, they calculate a ratio called relative risk. In this case, that would be the risk of developing prostate cancer by men consuming large amounts of dairy products compared to the risk for men who consume little or no such foods. If the difference between the groups is large enough, it may reach statistical significance, which means that the probability of getting such results by chance is highly unlikely (usually less than 1 in 20).
Typically, if the disease risk of the group consuming the most of a suspect product is less than double the risk of the comparison group, epidemiologists consider the link between product and disease to be a weak one. Of the 23 studies reviewed by Barnard, only three reported relative risks greater than 2.0; and these were not the largest, most recent, or best-designed studies. By comparison, the risk of developing lung cancer by people smoking one pack of cigarettes per day, compared to the risk for non-smokers, is about 10 (that is, 10 times as great) a number deduced from literally hundreds of studies. Now that's a risk factor that makes an epidemiologist sit up and take notice!
Despite the paucity of really solid data, PCRM persists in labeling dairy consumption as a cause of prostate cancer (for a more balanced review, please see ACSH's recent paper, Risk Factors for Prostate Cancer: Facts, Speculation and Myths). But the lead author of a recent paper about the Physicians' Health Study, Dr. June M. Chan, has been quoted as saying, "We do not recommend that people change their diets or stop drinking milk," despite their finding a 32% increase in risk of prostate cancer in men with high dairy consumption.
According to the PCRM, a strict vegetarian, or vegan, diet will cure what ails us. Another summary on their website relates the results of a small study that examines the effect of adhering to a vegan diet on individuals with type 2 diabetes, compared to a diet recommended by the American Diabetes Association. They found that those eating the very low fat vegan diet had better blood sugar control than did those on the Diabetes Association diet (which is not vegan or as low in fat). However, what the summary doesn't mention is the number of calories consumed by individuals on each diet. One can reasonably assume that the vegan diet had fewer calories than the other diet, since the vegans lost close to 16 pounds on average during the study, while the other group only lost eight pounds (the study lasted 12 weeks).
Predictably, the PCRM report attributes the greater success of those on the vegan diet to the lack of animal products, but a really valid comparison would be between the two diets at the same level of calorie intake.
Such examples strongly suggest that PCRM's main goal is not the dissemination of scientifically sound, reliable nutrition information to consumers. Indeed, by emphasizing only data that support their agenda, and by exaggerating the reliability and importance of such data, they obfuscate rather than clarify what can be a confusing body of information. Those who purport to represent consumer interests should be responsible enough to present accurate and balanced information to the public. Some groups obviously abdicate this responsibility.
