Being a party animal could in fact be good for the heart, according to a study linking loneliness with blocked arteries.

Researchers in the US found that socially isolated men had raised levels of a blood chemical called interleukin-6 (IL-6) linked to heart disease, reports the daily Scotsman.

The cell-signalling protein IL-6, known to promote inflammation that helps artery walls to thicken and harden, in turn can lead to heart attacks and strokes. In Britain alone, it is believed to kill 184,000 people each year.

As part of a major health investigation called the Framingham Heart Study, scientists studied 3,267 men with an average age of 62. They 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 they could confide in, and the extent of their participation in group activities and religious meetings or services.

Based on the results, the men were assigned a social network score of one to four - socially isolated men were at the bottom of the scale, and those who were highly connected at the top.

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 (1 gram = 10^12 picograms).

Men with a social network score of four had a level of 3.52 picograms per millilitre.

"This was a statistically significant difference," said the research leader, Eric Loucks from the Harvard School of Public Health in Boston, Massachusetts.

"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."

According to the researchers, the same link was not found for women.