Happily married women tend to have healthier hearts than those who are lonely or unhappy, scientists said on Wednesday.

A 10-year study of 600 women between the ages of 30 and 65 led by Swedish researcher Kristina Orth-Gomer found that happy and supportive relationships have a positive effect on the health of human hearts.

“Women suffering from stress in their marriages showed a marked increase in the narrowing of blood vessels,” Orth-Gomer told a German-hosted European congress on psychosomatic health problems in Berlin on Wednesday.

“But among happily married women, sclerosis of the arteries is more likely to clear up,” she added.

Lonely women’s hearts had a lower capacity to vary pulse rate, meaning they are less able to cope with physical strain. Socially isolated women also tended to be more at risk from obesity and diabetes, the study found.