Researchers found that men who were socially isolated had raised levels of a blood chemical linked to heart disease. The cell signalling protein, interleukin-6 (IL-6), is known to promote the inflammation that helps artery walls to thicken and harden. This can lead to heart attacks and strokes.

Scientists in the US studied 3267 men, with an average age of 62, who underwent physical examinations and answered a series of questions about their social lives. They were asked if they were single or married, how many friends and relatives they knew whom they could confide in and the extent of their participation in group activities and religious meetings or services.

The men were then assigned a social network score of one to four. Isolated men were at the bottom of the scale, and those who were highly connected at the top. The researchers found that the average level of IL-6 in the blood of men with a score of one was 3.85 picograms per millilitre. Men with a social network score of four had a level of 3.52 picograms. "This was a statistically significant difference," said the research's leader, Dr Eric Loucks, from the Harvard School of Public Health in Boston.

"Our analyses suggest that it may be good for the heart to be connected. In general, it seems to be good for health to have close friends and family, to be connected to community groups or religious organisations, and to have a close partner."

The researchers said the same link was not found for women.

Press Association