A new US study from the University of North Carolina at Chapel Hill has found that social relationships can be as important to good health as diet and exercise.

Published on Monday in the journal Proceedings of the National Academy of Sciences, the study provides new insight into how social connections can affect health throughout our lives.

In the study, the team of researchers looked at four nationally representative surveys on the US population to assess social relationships through different stages of life, from adolescence to old age, and looked at three different parts of social relationships: social integration, social support, and social strain.

To see how social connections at these different stages of life could affect health, the team also measured four key factors that are used when assessing mortality risk: blood pressure; waist circumference; body mass index; and levels of C-reactive protein, a measure of inflammation in the body related to the immune system.

The results showed that social isolation could have the same negative effect on health as other risk factors, with the team finding that in adolescence, social isolation increased the risk of inflammation in the body the same amount as physical inactivity, and in old age social isolation had an even more harmful effect on blood pressure than diabetes. Social integration was also shown to protect against abdominal obesity.

The team found that different factors of social relationships are more or less important at different stages of life: The size of a person's social network was particularly important for health in early and late adulthood, but in middle adulthood it was more quality than quantity, with the levels of support provided by social connections proving to be more beneficial to health than simply the number of connections.

Commenting on the results, Yang Claire Yang, a professor at UNC-Chapel Hill and co-author on the study, emphasized the importance of social relationships, "Our analysis makes it clear that doctors, clinicians, and other health workers should redouble their efforts to help the public understand how important strong social bonds are throughout the course of all of our lives," with co-author Kathleen Mullan Harris also adding, "Based on these findings, it should be as important to encourage adolescents and young adults to build broad social relationships and social skills for interacting with others as it is to eat healthy and be physically active."