"The science myths that will not die"

"This blind faith in cancer screening is an example of how ideas about human biology and behaviour can persist among people — including scientists — even though the scientific evidence shows the concepts to be false. “Scientists think they're too objective to believe in something as folklore-ish as a myth,” says Nicholas Spitzer, director of the Kavli Institute for Brain and Mind at the University of California, San Diego. Yet they do.

These myths often blossom from a seed of a fact — early detection does save lives for some cancers — and thrive on human desires or anxieties, such as a fear of death. But they can do harm by, for instance, driving people to pursue unnecessary treatment or spend money on unproven products. They can also derail or forestall promising research by distracting scientists or monopolizing funding. And dispelling them is tricky...

Scientists rallied around the free-radical theory of ageing, including the corollary that antioxidants, molecules that neutralize free radicals, are good for human health. By the 1990s, many people were taking antioxidant supplements, such as vitamin C and β-carotene. It is “one of the few scientific theories to have reached the public: gravity, relativity and that free radicals cause ageing, so one needs to have antioxidants”, says Siegfried Hekimi, a biologist at McGill University in Montreal, Canada.

Yet in the early 2000s, scientists trying to build on the theory encountered bewildering results: mice genetically engineered to overproduce free radicals lived just as long as normal mice⁴, and those engineered to overproduce antioxidants didn't live any longer than normal⁵. It was the first of an onslaught of negative data, which initially proved difficult to publish. The free-radical theory “was like some sort of creature we were trying to kill. We kept firing bullets into it, and it just wouldn't die,” says David Gems at University College London, who started to publish his own negative results in 2003"

http://www.nature.com/news/the-science-myths-that-will-not-die-1.19022