A recent report called “Food, Nutrition, Physical Activity and the Prevention of Cancer” has generated quite a buzz lately. It makes the fantastic claim that cancer is preventable if one follows its diet and lifestyle recommendations. Journalists the world over eagerly and uncritically accepted its findings while trumpeting it as the most comprehensive review ever published on the evidence linking cancer to diet, physical activity and weight. A few, however, asked the simple question, “Is it true?” They found that it was not.
Body fat, the report claims, is what causes cancer. The key to prevention, we are told, is to limit the amount of red meat, high-caloric foods, alcohol, refined carbohydrates and salt consumed. One should also avoid sugary drinks, fast foods and processed meats, eat mostly a plant-based diet, be active and, oh yes, stay as thin as possible within one’s normal weight range.
Steve Milloy of Junkscience.com pointed out the obvious: The claim that “no safe level of consumption” of processed meats is something that is not even true for the most poisonous of substances. He also sets the record straight, saying, “Scientists don’t really understand carcinogenesis very well. It’s known that the risk of cancer increases with age, possibly because of the deterioration of DNA repair mechanisms and a few well-documented risk factors, such as family history of cancer, heavy smoking and exposure to certain viruses and some exposures to radiation. Outside of those and perhaps a few other factors, the occurrence of cancer is largely inexplicable.”
On the surface, the 7,000 cancer studies used in the report sound impressive. However, as Professor John Brignell noted, these were “only the ‘relevant’ ones. The ‘irrelevant’ ones totaled 493,000. So, to add to all the other catch-phrases, we now have ‘relevancy’ and wonder what it means, other than producing the politically correct result.” A long-time critic of these kinds of meta-analysis, Brignell said, “This is a technique for trying to get a convincing result by combining the results of a lot of unconvincing studies.”
The most thorough debunking comes from nurse and veteran food journalist Sandy Szwarc’s Junkfood Science blog. After sifting through all of the studies listed in the report, she noticed that none of the relative risks mentioned were strong enough to be valid as defined by the National Cancer Institute.
Similarly, when Ms Szwarc looked at the report’s data on Body Mass Indexes (BMI), she found that it contradicted the conclusions. As BMIs slightly rise in each country, so do the average ages and life expectancies, but there is no relationship between cancer deaths and BMIs. The average BMIs in Egypt (with the lowest cancer deaths), for instance, are about the same as in Australia (with one of the highest cancer deaths) — but people live about 13 years longer in Australia.
Then she noticed the omission of the largest meat study to date. Researchers at Harvard examined 14 studies on 725,258 people investigating meat and fat and associations with colorectal cancer risk. They reported, “Greater intake of either red meat or processed meat was not related to colorectal cancer risk.”
Also missing was the study to end all studies on healthy eating, the $414-million Women’s Health Initiative Dietary Modification Trial. More than 19,000 women went on a strict diet, low in fat, high on fibre with a heavy dose of fruits and vegetables, for more than eight years. What this trial showed was that none of the expected benefits of healthy eating that we have been told repeatedly to expect actually occurred. There was no difference in the rate of breast cancer, colon cancer, heart attack or stroke or even a change in weight between those on the restrictive diet and the 29,294 women in the control group who ate whatever they wanted.
What is unhealthy with all of this is the obsession of the food activists and nutritional nannies in places of power who keep using bogus studies like these to justify getting between you and your waistline. People have a right to eat what they want to eat. It is a question of personal independence and responsibility, not one of dietary paternalism, and we do not need a -report- to figure that one out.