Drs. Keith and Penny Block attended the Annual Meeting of the American Association of Cancer Research (AACR) earlier this month, a large meeting that took place this year in San Diego, and which was attended by 18,500 researchers. The Association is an organization for researchers interested in all aspects of cancer research. At this year’s meeting, Dr. Keith Block presented a poster session on an experimental natural product drug called Anvirzel.
Last week, however, an online flap erupted between the Association and the equally prestigious American Institute for Cancer Research (AICR). The Institute, located in Washington DC, provides leadership, conducts studies and supplies funding for researchers working on cancer prevention. It’s known for its comprehensive analyses of the epidemiological literature on cancer, diet, physical activity and weight. The flap arose from an article published in the New York Times – historically not a big supporter of integrative medicine. The article described a talk given at the AACR meeting by Dr. Walter Willett, of Harvard University, a well known researcher in the epidemiology of diet and cancer. According to the Times article, Dr. Willett essentially said that there’s really no evidence linking fruits, vegetables or fatty foods to cancer prevention, noting the lack of randomized controlled trials in these areas. The only really important dietary factor, he said, is obesity, though alcohol consumption also has some relevance. The Times article went on to quote Willet as saying that although a 1997 report from the Institute concluded that diets high in fruits and vegetables could lower cancer risk, a 2007 follow-up study , also by the Institute, basically reversed the findings, citing no “convincing” evidence for dietary cancer prevention. For instance, red meat is now considered just fine, according to the Times, noting that the cancer researchers feasted on roast beef and fine cheeses at the Association reception that evening, courtesy of the MD Anderson Cancer Center. The Times went on to note that the only really interesting information presented at the meeting was about immunotherapies and chronic inflammation.
Well, this did not sit at all well with the Institute! That same day, the Institute’s blog published a piece flatly contradicting the Times article. Susan Higginbotham, PhD, RD, the Institute’s Director of Research, kicked off the blog. “Make no mistake…If there’s one thing the AICR’s research shows, and continues to show, it’s that when it comes to cancer risk, diet does matter.” Some of the findings from their research cited in the blog:
- Whole grains help protect against colorectal cancer.
- Carotenoid-containing foods like carrots and squash reduce the risk of mouth and throat cancer.
- Non-starchy vegetables such as broccoli, lettuces and beans, guard against esophageal cancer.
Further, the Association’s Continuous Update Project published a report in 2011 showing that there was now even more evidence linking diet and colorectal cancer than was apparent in their 2007 report.
The blog notes that Willett did say that there is continuing interest in the cancer preventive properties of some foods and nutrients, including calcium, vitamin D and blueberries. And they agreed with him that research on diet and cancer prevention is hard to do, especially randomized trials, which have to persuade thousands of people to make specific dietary changes over years-long study periods – which is, needless to say, no easy feat!
Our staff and researchers also had some thoughts about this dust-up between these giants in our field. For one thing, one of the problems that Willett was referring to is the inability of epidemiology to pick out specific food components, for example, fat or fiber, as being the most influential in causing cancer. We feel that’s really a red herring. As we’ve always maintained, it’s the total diet and lifestyle that’s important, not simply fat or fiber. It’s important to eat vegetables, fruits, whole, rather than refined grains, very little or, ideally, no refined sugar, mostly plant-based proteins – and also important to be exercising and managing the stresses of life in healthy ways. More researchers are starting to recognize this, producing studies on the whole dietary profile, and not just one component. The reductionistic effort to pin the blame on one component of a diet, whether it be high fat or low fiber, or any other single aspect of our diet for that matter, leads us all astray.
Another point that interested us is the concern with chronic inflammation, discussed at the Association meeting, and also mentioned in the Times piece. The scientific literature tells us that obesity tends to bring about a state of chronic inflammation, which may contribute to the development of cancer. However, whether you are obese or not, diet itself can also contribute to chronic inflammation. High levels of dietary omega-6s and low levels of omega-3 fatty acids, the consumption of refined sugar and flour, low fiber and whole grain intake, eating red meat and shunning fish — all of these contribute to chronic inflammation. Finally, for patients diagnosed with cancer, evidence is accumulating that healthy diets high in fruits, vegetables and whole grains do appear to contribute to better survival.
So, Dr. Willett and the Times notwithstanding, we feel there’s still plenty of evidence for you to build a healthful lifestyle around plant-based diets, exercise and a healthy approach to life’s stresses. Let’s leave the researchers to their beef and cheese, if they so choose, and, as spring progresses, we can concentrate on finding good local farmers’ markets and enjoying the wide variety of wonderful vegetables and fruits they have to offer!