One of the studies, which took into consideration 4,600 people with cancer over 30 years, found that irrespective of whether the patients were extrovert or neurotic, their attitude to life had no relationship with how long they survived their illness.
It is not an isolated finding. An analysis of research by Dr James Coyne, professor of psychology at the University of Pennsylvania School of Medicine, found that there were no good quality studies showing that 'positive psychology' had any effect on physical health, the Daily Mail reported.
In one of his own large studies, he found that the sense of emotional well being of cancer patients had no impact on how long they lived.
British researchers and health staff are becoming worried that lifestyle gurus who urge people to 'be positive and live longer' may be doing more harm than good.
Claire Murrell, head of nursing at the Barts and the London Hospital Cancer Unit, asserted that too many people are being told to 'be positive' after a cancer diagnosis, when they need to be realistic and realise they will experience emotional lows.
"I think that some people with cancer do come down with a bump when they realise that, for all their positive attitude, they haven't been cured," she said.
Research on 1,000 people attending the famous Mayo Clinic in the U.S. over 30 years revealed that those classified as optimists had a 19 per cent higher chance of still being alive than pessimists.
But this is all different from saying that taking a positive attitude makes you healthier.
Dr Gerard Molloy, chair of the UK Society For Behavioural Medicine's scientific committee, said that while psychological traits such as optimism may be linked to longer survival from illness, there is no evidence that such traits can be cultivated by 'positive thinking'.
"For me, remaining positive is sometimes harder than dealing with the chemo side effects and having cancer," Molloy said.
"Some of the strongest evidence revolves around personality types."
"But personality type is, by definition, impossible to change. I think the idea of adopting a positive psychology has come over from the U.S., where there's a "Yes we can" culture, and the wellness thing is hanging on to the coat-tails of that," he added.