In the fight against the disease that will kill one of every four people you know, most scientists studying cardiovascular epidemiology at Harvard School of Public Health are focusing on usual suspects like cholesterol, obesity, and cardiac structure. But research fellow Eric Kim has a unique focus: purpose in life. How does it affect health, how is it gained and lost, and how can it be weaponized to keep people alive and well?

When Canadian tenth-graders in a recent study began volunteering at an after-school program for children, the high schoolers lost weight and had improved cholesterol profiles compared to their non-volunteering peers. (Even in Canada, teenagers have cholesterol problems.) In the journal JAMA Pediatrics, the researchers concluded, “Adolescents who volunteer to help others also benefit themselves, suggesting a novel way to improve health.”

In another randomized controlled trial at Washington University in St. Louis, older adults who began tutoring children through a program called Experience Corps demonstrated improvements in stamina, memory, and flexibility, as well as levels of depression. When I spoke with Kim last year, he attributed at least part of those gains to the effects of a sense of purpose in life. And he is continuing to do observational studies in hope of figuring out how and why volunteering seems to lead to better health. To date, research in the area has been focused on the associations between volunteering and health status and mortality risk (24 percent lower); it has only scratched the surface on understanding mechanisms and implications for the health-care system and how real people can use this information.

In the January 2016 journal Social Science and Medicine, Kim now reports new findings that further a case for adding volunteering to the list of things that physicians recommend to all patients.

His collaborator on the study, Sara Konrath, is the director of the Interdisciplinary Program on Empathy and Altruism Research at Indiana University’s Lilly Family School of Philanthropy (the world’s first school dedicated to the study of philanthropy, aptly named for the generous donors who made it possible). Together Kim and Konrath studied 7,168 Americans over age 50, only some of whom did volunteer work in their communities. After adjusting for a wide range of confounding variables, they found that over a two-year period, volunteers were more likely to get flu shots, mammograms, Pap smears, cholesterol tests, and prostate exams. Most importantly, volunteering was associated with 38 percent fewer nights spent in the hospital.

“What this shows is that volunteers make decisions about their health that are different from non-volunteers,” Konrath told me. “One way to think about this is that when we care for ourselves, in a fundamental way, it allows us to care for others.”

When she describes this research to people, their initial reaction is sometimes skeptical. Of course, unhealthy people volunteer less because they are unable to volunteer. But then another of course, having spent much of her career researching associations between health and volunteering, Konrath has thought of this. So in addition to isolating sociodemographic factors like age, gender, race, ethnicity, marital status, educational attainment, financial wealth, and health-insurance status, Kim and Konrath controlled for health behaviors, social integration, stress, positive psychological factors, personality factors, chronic illnesses, and health status via two measures of baseline health, including a 23-item measure of functional status and an index of major chronic illnesses.

“The research on smoking is not experimental; it’s the exact same quality as the studies of volunteering,” said Konrath. “It’s based on following people over time and seeing what happens to people who choose to smoke or choose to volunteer. Yet doctors have no trouble telling us to stop smoking. What they ignore is that most of the context of our day-to-day lives is embedded within relationships. The number and quality of those relationships strongly influences health. I’ve been looking at this for years now, and I haven’t found a study where volunteering didn’t affect health positively in some way.”

“We tried to isolate purpose in life as one of the mechanisms,” Kim said, bringing it back to his specialty, “and we found that it did explain some of the association. But it wasn’t everything. Personality traits (like conscientiousness), social connection, health behaviors—all of these things explain some but not all of it. But together, it ends up keeping them out of the hospital, which ends up saving everyone money.”

These programs may offer new ways of increasing preventive health-care use and decreasing illness-based health-care use, which in turn may help drive down health-care costs, argue Kim and Konrath. Amid a crisis of exorbitance in a fetid system that spends $3 trillion annually, ways to enhance the health of the population at little cost—or no cost, or negative cost—are the grand prize for public health. Volunteering programs may be one. In 2012, 64.5 million American volunteers provided 7.9 billion hours of service, which the Corporation for National and Community Services estimated was worth $175 billion. If, in addition to that, health-care costs dropped, that value could be … large.

More importantly, volunteer programs could simultaneously enhance society and the health of a large segment of people. But there is an important wrinkle in applying this information.

After meeting Konrath recently to collaborate, Kim learned of one of her prior studies, the results of which concerned him. In an observational study, she had found that people who volunteered for “self-oriented” motives like “I need to get away from my problems” had a mortality risk that was similar to non-volunteers. As Kim explains, “Only the people who were doing it for more outward reasons–compassion for others–had reduced rates of mortality.”

“Before seeing that study, I thought it would be interesting if everyone (who has the time and financial resources to do so) were encouraged to volunteer,” Kim said. “It would help society, people’s health, and also reduce national health-care costs. But I guess people would have to have the right motives for this to work out.”

So that suggests that a sense of purpose is playing a role in this effect?

“I think so. Another thing it suggests is that if people start prescribing volunteering for better health, it might not work, because their motives might matter.”

So if I write about this, and people who volunteer start to be motivated by their own health concerns, is that ruining this effect for them?

“Yep, this whole project, I was thinking about that, too.”

So, don’t volunteer for your own health. In fact, now knowing that volunteering may be beneficial to your health, I hope I haven’t robbed you of that benefit. Try and forget everything you’ve just read.

Still, even if you go into volunteering for the wrong reasons, it’s hard to stay self-interested once you’re immersed in a cause and woven into the lives of people who need you.

“I think people who are affluent become isolated and get disconnected from the harsh realities of being disadvantaged, what that actually means,” said Kim. “Generally, if you take people who lack empathy, like Pharma Bro or the affluenza kid, and get them into volunteering, it kind of shifts that focus. ... Maybe if we want people to get health benefits from volunteering we have to someone win their hearts and minds. What would that look like? I don't know.”

It might look something like the principles of effective altruism, which is the fashionable, generally utilitarian art of applying evidence to determine the most efficient ways to improve the world. A group studying effective altruism at MIT explains that it uses data to identify projects with opportunity for scale (improving a large number of lives) and tractability (creating a measurable difference) while addressing a cause that has been previously overlooked or undervalued.

Effective altruists tend to favor large-scale public-health programs that are proven to be effective, like providing mosquito netting to prevent transmission of malaria. When you can demonstrate to people just how impactful and necessary their work can be—really making a difference, as opposed to spinning your wheels in a world beyond repair—people may be moved to take up a cause. And if Kim is right that it confers a genuine sense of purpose, the reciprocal health effects stand to be even greater.

This might explain why effective altruism has become a hip trend, while I hear fewer people professing passion for ineffective altruism.

Despite the growing body of evidence for what appears to be a high-yield, low-risk health intervention, Kim and Konrath conclude their current study in the guarded fashion unfortunately reserved for only the most reasonable of scientists: “If future research corroborate our findings, programs designed to encourage volunteering among older adults may be warranted.”

Certain political figures might call this recommendation “low energy.” Especially given the dire states of American health-care spending and national social cohesion. But as Kim and Konrath note, “Discovering an explanation for these results is essential in order for the field to advance and in order for researchers to begin outlining practical recommendations.”

Still Konrath is more candid outside the pages of the academic journal. “I think doctors should tell people about the health benefits of social activities, including volunteering,” she said. To avoid the nullifying effect of doing it for the wrong reasons, recommend volunteering for something you care about. “I’m willing to make that suggestion, because at this point I think it would be irresponsible to wait another decade to figure out exactly what happens to your heart when you're volunteering.”