Brigham Young University professors Julianne Holt-Lunstad and Timothy Smith report that low social interactions are as bad as - smoking 15 cigarettes a day, being an alcoholic, or twice as harmful as obesity.
The researchers conducted the study by analysing previous data that measured frequency of human interaction.
"The data simply show whether they were integrated in a social network," Holt-Lunstad said.
"When someone is connected to a group and feels responsibility for other people, that sense of purpose and meaning translates to taking better care of themselves and taking fewer risks," Holt-Lunstad added.
The researchers added that the results applied not only to older adults but were true across all age groups.
The study is published the journal PLoS Medicine.