Having a well-educated spouse reduces men's risk factors for heart disease, such as leading a sedentary lifestyle and being overweight.

The Norwegian researchers suggest well-educated women may have a calming effect on their husbands, and may have a positive influence on dietary and lifestyle habits.

Researchers looked at the health of 20,000 married men aged 35 to 56 who were part of a national survey looking at cardiovascular disease and risk factors.

They monitored them from 1977 to 1992.

Sometimes an educated wife is health damaging and sometimes she is health promoting

Dr Karen Matthews, University of Pittsburgh

They took information about their blood pressure and cholesterol levels, weight, smoking and exercise habits.

The men were also asked if they had a history of heart attacks or angina, and if they were taking medication to reduce blood pressure.

In just over 6,000 men, wives were less well educated than their husbands, while in 5,000 cases, the wives were better educated.

The rest had similar levels of education.

Risk

The researchers found that the better educated the wife was, the less likely their husbands were to have high risk factors for CHD.

In addition to being less likely to be overweight and take little exercise, having an educated wife was more likely to mean men had lower blood pressure and cholesterol and smoked less.

Previous research has found high levels of CHD risk amongst men married to a highly educated women, compared to those married to women who are not as well educated.

But the Norwegian research discovered men educated to 18 or above who were married to women of the same educational level had a 50% reduced risk of dying of coronary heart disease compared to those married to a woman with a lower level of education.

But less well-educated men married to more educated women saw no benefits.

Researchers say this could be explained by the small group of men studied in that group.

Better health for both

Dr Haakon Meyer of the Institute of Nutrition Research at the University of Oslo, one of the researchers on the study, told BBC News Online: "This paper suggests that educated men married to educated women do better.

The research does not tell us anything about the husband's background and how that may influence his risk of developing coronary heart disease

Belinda Linden, British Heart Foundation

"This may be because the women make decisions about nutrition and lifestyle."

In an editorial in the journal, psychiatrist Dr Karen Matthews of the University of Pittsburgh, Pennsylvania, USA, said the contrast between the findings of this study and previous studies meant there was no clear answer about whether a clever wife helped a man's health.

"At present, the answer is sometimes an educated wife is health damaging and sometimes she is health promoting."

She added that increasing education of women was likely to lead to their families having more access to resources and higher prestige, and therefore to better health for both husbands and wives.

Belinda Linden, of the British Heart Foundation, said: "This large long-term study confirms already existing strong evidence that socio-economic status affects peoples risk of developing coronary heart disease.

"It is not surprising that people in higher socio-economic groupings are less likely to develop CHD as they often have a better standard of health education.

"Partners are often influenced by each other and share many patterns of lifestyle, such as diet, smoking and physical inactivity."

She added: "The results from this study are interesting, and confirm what we already have found regarding socio-economic status.

"However, the research does not tell us anything about the husband's background and how that may influence his risk of developing CHD."