The health benefits of being married are so large that single men are at greater risk of dying than smokers, says a study.

The study looked at comparative risks over a seven year period - but experts warned that the lifetime risks of smoking were much higher.

Scientists have frequently found that married men and women tend to be in better health than their single counterparts.

This is partly because of the "social support" of having a wife or husband - and perhaps because both single men and women have a worse lifestyle - and no-one to look out for their wellbeing.

It is as clear as day from the data that marriage, rather than money, is what keeps people alive

Professor Andrew Oswald, Warwick University

However, the latest study, by researchers at the University of Warwick, looked at thousands of records from the British Household Panel Survey and the British Retirement Survey.

It found that, even when the effects of smoking, drinking and other poor lifestyles were taken into account, married men had a much lower risk of death.

Over a seven year period, the married male had a 9% lower risk of dying compared with an unmarried one.

When smoking and drinking in this group was taken into account, the benefit was reduced to 6.1%.

Not money

The effect was less for women - reducing the risk of mortality by 2.9%.

According to the Warwick calculations, a male smoker had a 5.8% greater risk of dying, and a female smoker 5.1% extra risk.

Professor Andrew Oswald, who led the research, suggested that male smokers should get wed as soon as possible to counteract the risk.

He said: "Forget cash. It is as clear as day from the data that marriage, rather than money, is what keeps people alive.

"It makes perfect sense to ask how a ring of gold can possibly do this.

"But the honest answer is, that we don't know."

However, while over a seven year period, the risks of smoking compared to single life might be roughly comparable, the lifetime risk to smokers is much higher.

A long-term smoker is thought to have a one in two chance of dying prematurely.

Whether the lifetime risk of being single even begins to approach this figure is highly dubious.