Superfoods and antioxidants can trigger cancer, says a scientist.
James Watson, who helped discover the structure of DNA, said that the cure for many cancers will remain elusive unless scientists rethink the role of antioxidants, which include vitamin pills and food such as blueberries and broccoli, the Daily Mail reported.
It is widely believed that they boost health and fight cancer by mopping up oxygen molecules called free radicals.
But Dr Watson argues that these may be key to preventing and treating cancer - and depleting the body of them may be counter-productive.
Free radicals not only help keep diseased cells under control, they are also pivotal in making many cancer drugs, as well as radiotherapy, effective, he said.
Writing in a journal published by the Royal Society, the 84-year-old Nobel laureate stated that antioxidants may have caused more cancers than they have prevented.
"For as long as I have been focused on the curing of cancer, well-intentioned individuals have been consuming antioxidative nutritional supplements as cancer preventatives, if not actual therapies," he said.
"In light of recent data strongly hinting that much of late-stage cancer's untreatability may arise from its possession of too many antioxidants, the time has come to seriously ask whether antioxidant use much more likely causes than prevents cancer," he added.
He said a vast number of studies had found antioxidants including vitamins A, C and E and the mineral selenium, to have "no obvious effectiveness" in preventing stomach cancer or in lengthening life.
Instead, they seem to slightly shorten the lives of those who take them, and vitamin E may be particularly dangerous.
The American, who describes his theory as among his most important work since the DNA breakthrough with British colleague Francis Crick in 1953, said blueberries may taste good but give no protection against cancer.
The study is published in the journal Open Biology.