Sept. 3 (UPI) -- Acts of kindness are often associated with selflessness, the opposite of selfishness, but new research suggests doing good is good for the giver, too, according to a new study published Thursday in the journal Psychological Bulletin.
Researchers found, however, that some acts of kindness provide a bigger health boosts than others, and that the health benefits offered by acts of kindness depend on a variety of factors.
"Prosocial behavior -- altruism, cooperation, trust and compassion -- are all necessary ingredients of a harmonious and well-functioning society," lead study author Bryant P.H. Hui said in a news release.
"It is part of the shared culture of humankind, and our analysis shows that it also contributes to mental and physical health," said Hui, a research assistant professor at the University of Hong Kong.
Previous studies have hinted at the health benefits of prosocial behavior, but results have been mixed, leaving the link between altruism and improved mental and physical health in doubt.
To better understand why investigations into the phenomena have produced varying results, Hui and colleagues conducted a meta-analysis of more than 200 different studies, comprising nearly 200,000 study participants.
Their analysis showed a small but meaningful mental and physical health boost among people who perform acts of kindness on a daily basis.
"More than a quarter of Americans volunteer, for example," Hui said. "A modest effect size can still have a significant impact at a societal level when many people are participating in the behavior."
Researchers found a stronger health boost resulted from more informal acts of kindness, such as helping an elderly neighbor carry in groceries, as opposed to more formal altruistic behavior, like signing up to volunteer at the local soup kitchen.
The meta-analysis also revealed a stronger connection between altruistic behavior and mental health among younger study participants, while older participants performing acts of kinds reported improved physical health. Women who performed daily acts of kindness also reported greater improvements in well-being than men who were equally altruistic.
In future studies, researchers plan to examine how a givers' ethnicity and social class impact the health boost they derive from good deeds. Researchers also plan to investigate whether there is an ideal level of prosocial behavior, or a level beyond which benefits decline.