Healthy ‘social connections’ – with relatives, friends, neighbours or workmates – can improve our odds of survival by 50 per cent, the study found.
But being a hermit can be as unhealthy as smoking 15 cigarettes a day, being an alcoholic, doing no exercise – and can even be twice as bad for us as being obese.
Professor Julianne Holt-Lunstad, from the Department of Psychology at Brigham Young University, said: “The idea that a lack of social relationships is a risk factor for death is still not widely recognized by health organisations and the public.
“When someone is connected to a group and feels responsibility for other people, that sense of purpose and meaning translates to taking better care of themselves and taking fewer risks.”
The researchers looked at data from 148 previous studies that measured human interaction and tracked health outcomes for a period of seven and a half years on average.
Because information on relationship quality was unavailable, the 50 per cent increased odds of survival may underestimate the benefit of healthy relationships.
Professor Holt-Lunstad said: “The data simply show whether they were integrated in a social network.
“That means the effects of negative relationships are lumped in there with the positive ones. They are all averaged together.”
Study co-author Professor Timothy Smith, who works alongside Professor Holt-Lunstad, said the results did not just stem from elderly people living longer – with men and women of all ages benefitting from close relationships.
The Professor also said that modern conveniences and technology have lead some to think that good friendships aren’t necessary – but that this was not the case.
He said: “This effect is not isolated to older adults. Relationships provide a level of protection across all ages.
“We take relationships for granted as humans we’re like fish that don’t notice the water.
“That constant interaction is not only beneficial psychologically but directly to our physical health.”