People who reported that they were socially isolated or felt lonely were more likely to die early from all causes including cancer, according to a sweeping review of 90 studies that included more than 2.2 million people from around the globe.

People who are socially isolated or lonely may be less likely to eat a healthy diet and get regular exercise and more likely to smoke and consume alcohol. In addition, social isolation is linked to inflammation and weakened immune systems.

People who are socially isolated may be less likely to receive medical care due to their smaller social networks.

Social isolation and loneliness are not one and the same, the researchers pointed out. Social isolation refers to a lack of contact with other people. By contrast, loneliness is the feeling of being alone, regardless of social contact.

For the study, researchers led by Maoqing Wang and Yashuang Zhao from Harbin Medical University in China reviewed 90 studies. People who reported being socially isolated and feeling lonely were more likely to die early from all causes including cancer. What’s more, social isolation was linked to an increased risk of dying from heart disease.

The findings were published online in Nature Human Behaviour.