People can lower their chances of being diagnosed with dementia, heart disease and diabetes by following five simple rules, scientists claim.
Research from Cardiff University's School of Medicine found that exercising, not smoking, only drinking moderately, eating healthily and maintaining a low body weight have benefits which last well into later life.
The team say that sticking to four of these rules will lower the risk of dementia by 60 per cent, while instances of diabetes, stroke and heart conditions will be minimised by 70 per cent.
The study ran for a period of 34 years and identified regular exercise as the most beneficial of the rules.
Professor Peter Elwood, who led the study, said: "What the research shows is that following a healthy lifestyle confers surprisingly large benefits to health – healthy behaviours have a far more beneficial effect than any medical treatment or preventative procedure.
"Taking up and following a healthy lifestyle is, however, the responsibility of the individual him or herself. Sadly, the evidence from this study shows that very few people follow a fully healthy lifestyle."
He added that the number of people who smoke has fallen sharply since the study started in 1979, but this does not mean that more people are leading a healthy lifestyle.
Indeed, only one per cent of the population follows all five of the rules and just five per cent adhere to four.
Dr Doug Brown, director of research and development at the Alzheimer's Society, said the study is further evidence that "what is good for your heart is also good for your head".
Christopher Allen, senior cardiac nurse at the British Heart Foundation, added that he hopes the study's findings will go some way to encouraging people to think about how their current lifestyle will impact on their health in the future.