Evidence-based health policies don’t necessarily mean credible evidence

If we believe a thousand news stories that appeared in lockstep today, a new study just released by the World Cancer Research Fund and the American Institute for Cancer Research found that “cancer is mostly preventable with clean living.”

The new policy report “is based on an exhaustive review of nearly 7,000 scientific studies” and said to have found that bad diets, obesity and sedentary lifestyles cause one out of three cancers.

“It's a very compelling case,” Shiriki Kumanyika, Ph.D., MPH at the University of Pennsylvania in Philadelphia and a member of an expert panel that oversaw the report, told the media. “I definitely feel confident,” that the scientific evidence strongly supports that poor diet, obesity and lack of exercise cause at least one out of three cancers. “Cancer is not inevitable,” she said. “When it comes to cancer prevention,” she said, the evidence shows that what’s important are nonprocessed foods higher in water and lower in calories. After its earlier 2007 Expert Report identified the healthy choices to prevent cancer, this new report “takes the next step,” said Kumanyika.

According to the press release, Policy and Action for Cancer Prevention is a “landmark policy report” providing “comprehensive, evidence-based recommendations for all levels of society.” It calls for sweeping global changes in public health policies and for governments to use all measures at their disposal to advance healthy behavior and diets based on fruits, vegetables and whole grains and low in fats, sugars, salt, meats and dairy. Its recommendations include nonprofits, the United Nations, governments, industry, media, schools, workplaces and healthcare settings.

“On a global level every year, there are millions of cancer cases that could have been prevented and this is why we need to act now before the situation gets even worse,” lead author, Michael Marmot, said. “Promoting public health is not just the responsibilities of governments and health departments,” said the AICR report, “but is shared by all sections of society.”

How many public health officials, deciding what’s best for all of us, will bother to go to the original scientific studies behind these far-reaching recommendations — and how many will just take the word of “experts?”

An actual examination of those “7,000 scientific studies” in the 517-page Expert Report found that not one of its key recommendations had been supported in clinical studies. In fact, the Report not only failed to provide what most scientists would consider convincing evidence, its conclusions were repeatedly the opposite of the evidence. The lengthy JFS examination [here] found that none of the 17 cancers examined in the WCRF/AICR Expert Report had found credible associations with foods (sugars or sugary drinks, fats, meats, fruits, vegetables, legumes, vitamins, alcohol or processed foods) or BMI.

“Evidence-based” is another example of doublespeak that doesn’t always mean what it seems.