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" Two large trials of antioxidants were set up after Peto’s paper (which rather gives the lie to nutritionists’ claims that vitamins are never studied because they cannot be patented: in fact there have been a great many such trials, although the food supplement industry, estimated by one report to be worth over $50 billion globally, rarely deigns to fund them). One was in Finland, where 30,000 participants at high risk of lung cancer were recruited, and randomised to receive either ß-carotene, vitamin E, or both, or neither. Not only were there more lung cancers among the people receiving the supposedly protective ß-carotene supplements, compared with placebo, but this vitamin group also had more deaths overall, from both lung cancer and heart disease. The results of the other trial were almost worse. It was called the ‘Carotene and Retinol Efficacy Trial’, or ‘CARET’, in honour of the high p-carotene content of carrots. It’s interesting to note, while we’re here, that carrots were the source of one of the great disinformation coups of World War II, when the Germans couldn’t understand how our pilots could see their planes coming from huge distances, even in the dark. To stop them trying to work out if we’d invented anything clever like radar (which we had), the British instead started an elaborate and entirely made-up nutritionist rumour. Carotenes in carrots, they explained, are transported to the eye and converted to retinal, which is the molecule that detects light in the eye (this is basically true, and is a plausible mechanism, like those we’ve already dealt with): so, went the story, doubtless with much chortling behind their excellent RAF moustaches, we have been feeding our chaps huge plates of carrots, to jolly good effect. Anyway. Two groups of people at high risk of lung cancer were studied: smokers, and people who had been exposed to asbestos at work. Half were given 3-carotene and vitamin A, while the other half got placebo. Eighteen thousand participants were due to be recruited throughout its course, and the intention was that they would be followed up for an average of six years; but in fact the trial was terminated early, because it was considered unethical to continue it. Why? The people having the antioxidant tablets were 46 per cent more likely to die from lung cancer, and 17 per cent more likely to die of any cause,* than the people taking placebo pills. This is not news, hot off the presses: it happened well over a decade ago. "
― Ben Goldacre , Bad Science
