Friendship and health: why social ties weighed more than too little exercise in 148 studies

General information, not medical advice. If you have felt lonely or low for a long time, talk to your GP or to someone you trust.

Over the All Saints’ weekend you may be sitting at the table with family and realise which friends you have not spoken to in ages. In large studies, friendship and other strong social ties go hand in hand with a longer life. The link was as strong as for smoking and stronger than for too little physical activity. So friendship does not replace exercise. It is a second pillar alongside moving, sleeping and eating well.

What 148 studies say about friendship and a longer life

A meta-analysis is a study that combines the results of many separate studies. In 2010, American researchers pooled 148 studies with a total of 308,849 participants in the journal PLoS Medicine. People with stronger social relationships had on average a 50 percent higher chance of still being alive during follow-up.

The link was strongest for what the researchers call social integration. This is a measure that looks at several sides of your social life at once, such as whether you have a partner, how large your network is and whether you take part in activities with others. According to the authors, the influence of social relationships on the risk of dying is comparable to that of smoking and alcohol. It is greater than that of physical inactivity and obesity.

Being alone is not the same as feeling lonely

A second meta-analysis from 2015 makes a useful distinction. Social isolation means you have little contact with others. Loneliness is the feeling that your relationships fall short, even when there are people around you. Living alone is something else again. In studies that accounted for other possible explanations, all three were linked to a higher chance of dying: on average 29 percent for social isolation, 26 percent for loneliness and 32 percent for living alone. The link was stronger, though, in studies where participants were on average younger than 65.

In a 2025 report, the World Health Organization estimates that 1 in 6 people worldwide is lonely. Loneliness would account for about 871,000 deaths a year. How to build contact with others into your day is covered in a separate article.

What the Harvard study shows after 50

In 1938, researchers of the Harvard Study of Adult Development began following the health of 268 Harvard sophomores. There were no women, because the university only admitted men at the time. In the 1970s, 456 men from working-class neighbourhoods in Boston joined the study.

Those who were most satisfied with their relationships at 50 were the healthiest at 80. In several studies within this project, that satisfaction at 50 even predicted later physical health better than cholesterol levels did. Among couples over 80 who often bickered, their memory did not suffer from the arguments as long as they felt they could count on each other when things got hard. Study director Robert Waldinger summed it up in the Harvard Gazette: taking care of your body is important, but tending to your relationships is a form of self-care too.

A link, not proof

All of these studies are observational. Researchers follow people and look at what happens later, without changing anything themselves. They show a link, not proof of cause and effect. It may also be, for example, that healthier people find it easier to keep friends. Even so, strong social ties weigh as heavily in these studies as well-known risk factors. If you already look after your body, you can add a second pillar.

Maintain friendship like your fitness

You build fitness with a regular schedule. Friendship works the same way: what you do not plan gets pushed back. A few ways to start:

• Arrange a regular walk with a friend on a fixed day, so you do not have to decide on it every time.
• Join a club, a choir or a walking group.
• Start small: send an old friend a message or call back someone who has been waiting for a reply.
• Combine both: walking together counts for your body and for your friendship. How many steps a day really make sense is explained in another article.

That way friendship becomes a fixed habit alongside the other levers for more healthy years.

Sources

• Holt-Lunstad J, Smith TB, Layton JB. Social relationships and mortality risk: a meta-analytic review. PLoS Medicine, 2010 (meta-analysis of 148 studies).
• Holt-Lunstad J, Smith TB, Baker M, Harris T, Stephenson D. Loneliness and social isolation as risk factors for mortality: a meta-analytic review. Perspectives on Psychological Science, 2015 (meta-analysis).
• Mineo L. Good genes are nice, but joy is better. Harvard Gazette, 11 April 2017 (on the Harvard Study of Adult Development).
• World Health Organization. Commission on Social Connection: From loneliness to social connection. Report of 30 June 2025.