Enjoying the company of others is a key to mental and physical well-being. And now there's hard physical evidence to support this idea.

Loneliness leaves a “signature” in the proteins of a person's blood, British and Chinese researchers have found. Socializing reduces these proteins and the risk of common illnesses such as heart disease, type 2 diabetes and stroke.

Research teams from the University of Cambridge in the United Kingdom and Fudan University in China came to this conclusion after studying nearly 3,000 proteins found in blood samples taken from more than 42,000 adults between the ages of 40 and 69 as part of the UK Biobank, a large-scale biomedical database and research resource.

Find an activity that you enjoy, restart an old hobby or take a class to learn something new. You might have fun and meet people with similar interests.

To begin, the researchers calculated participants' social isolation and loneliness scores based on the answers they gave to questions about things like whether someone lived alone, how frequently they had contact with others socially and if they took part in social activities. The team adjusted for factors such as age, sex and socioeconomic background.

Then the teams looked at specific proteins circulating in the participants' blood. They identified 175 that were associated with indications of social isolation and 26 associated with loneliness. There was considerable overlap — 85 percent of the proteins were associated with both loneliness and social isolation.

“We know that social isolation and loneliness are linked to poorer health, but we've never understood why,” lead author, Chun Shen, from the Department of Clinical Neurosciences at the University of Cambridge and Fudan University in China, said in a press release. “Our work has highlighted a number of proteins that appear to play a key role in this relationship, with levels of some proteins in particular increasing as a direct consequence of loneliness.”

One of the proteins produced at higher levels in relation to loneliness was ADM or adrenomedullin peptide. ADM acts as a vasodilator, meaning it helps to widen blood vessels and is primarily associated with regulating our blood pressure and fluid balance.

The team identified proteins that offer clues to the biology behind some of the poor health seen among people who are socially isolated or lonely.

This identification of specific proteins affected by loneliness proved to be invaluable. “The proteins we've identified give us clues to the biology underpinning poor health among people who are socially isolated or lonely, highlighting why social relationships play such an important part in keeping us healthy,” researcher, Jianfeng Feng, from the University of Warwick and Fudan University, said.

Loneliness and isolation are ongoing concerns. So much so, that in May 2023, the U.S. Surgeon General, Vivek Murthy, issued a report that drew attention to the prevalence of loneliness, pointing out that it affects 1 out of 2 American adults.

Given that loneliness is not good for our mental and physical health, what are some ways that we can increase our time among others? The National Institute of Aging suggests:

  • Find an activity that you enjoy, restart an old hobby or take a class to learn something new. You might have fun and meet people with similar interests.
  • Schedule time each day to stay in touch with family, friends and neighbors in person, by email, social media, voice call or text.
  • Use communication technologies such as video chat or smart speakers to help keep you engaged and connected.
  • Consider adopting a pet if you are able to care for one. Animals can be a source of comfort and may also lower stress and blood pressure.
  • Find ways to exercise with others, such as joining a walking club or working out with a friend. Adults should aim for at least 150 minutes (2.5 hours) of moderate-intensity activity each week.
  • Introduce yourself to your neighbors.
  • Check out resources and programs at your local social service agencies, community and senior centers and public libraries.
  • Volunteer for a cause you care about and get involved in your community.

The study is published in Nature Human Behaviour.