Why do ecomyths persist even when the science exists to invalidate them?
Here, courtesy of Junkfood Science, is an excellent illustration of this phenomenon.
The ecomyth is this instance is a variant of the obesity and health myth: in this variant, sugar is blamed for causing cancer.
- The sugar-cancer fear has the veneer of science, fuelled by reports made to appear scientific. Like all food fears, this one is nothing new. Each time it's been debunked, it resurfaces using a different technique or elaborate theory attempting to convince us that it is based on science.
- ...there is no truth to the rumor that sugar causes cancer, or that people with cancer shouldn't eat sugar because it causes cancer to grow faster...
- But that hasn't stopped people from continuing to blame cancer on sugars.
The latest study was reported by the media as having found "conclusive evidence" that eating sugary cereals, white bread and other carbohydrates with high glycemic index increase risks of cancer and other modern "lifestyle diseases." The published paper was a meta-analysis of 37 published observational (epidemiological) studies that had looked for correlations between glycemic index/load (GI/GL) and diseases. However,
- ...try as they might, they were unable to find a viable correlation between GI/GL and any disease. None of the 37 studies, separately or lumped together, could come up with a tenable link.
So all the data fail to indicate any link, any correlation (an we won't even address the question of the study design, the absence of control groups etc.). To a normal person, the absence of any data showing any correlation would seem to indicate what? That there is no relationship. Right? Well not so quick:
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The researchers, however, arrived at a different conclusion:
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This meta-analysis provides high-level evidence that diets with a high GI, high GL, or both, independently of known confounders, including fiber intake, increase the risk of chronic lifestyle-related diseases. The effect was modest overall... Overall, the GI had a more powerful effect than did the GL... The findings indicate that the judicious choice of low-GI foods offers a similar or higher level of protection as whole-grain foods or high fiber intake in the prevention of chronic lifestyle-related disease.
The explanation for this dramatic contrast of conclusion with reality? with the study's own data?
- Not mentioned by any news reporter was that, except for the statisticians, the researchers who conducted this study are authors of GI diet books. Not only that, but they are with a GI testing service and a GI-based licensing program...
As Sandy writes: It's not science itself that we can't trust, it's the bad portrayals of science.
In contrast to the one study that did garner all the media attention, another study on the same subject also was published last week. This one was an epidemiological study, of over 120,000 people over an 11 year period. Its conclusion?
- "Overall, our findings do not support the hypothesis that a diet with a high glycemic load or index is associated with a higher risk of colorectal cancer."
- And conversely, low-glycemic foods aren't associated with lower risks.
- There is no link.
There is no one right way for us all to eat, no optimum diet. Being well-fed is important, but trying to invoke fear about 'bad' foods that give cancer and shorten life-spans, is not supported by the scientific data: it is an ecomyth.
