(Reuters Health) - For low-income U.S. adults, enrollment in the Supplemental Nutrition Assistance Program (SNAP) may be associated with lower health spending, a new study suggests.

SNAP provides a monthly grocery allowance to roughly one in seven Americans, researchers note in JAMA Internal Medicine. The federal government determines eligibility based on household income, but enrollment policies vary by state.

For the study, researchers examined data on health spending for U.S. adults who were eligible for SNAP, including 1,889 people who were SNAP participants and 2,558 who were not.

Overall, SNAP participation was associated with about $1,400 less in average annual health care costs for each low-income adult, the study found.

“We already had a good understanding that food insecurity was associated with increased health care costs, but we didn’t know if programs that address food insecurity, like SNAP, could reduce costs,” said lead study author Dr. Seth Berkowitz of Massachusetts General Hospital and Harvard Medical School in Boston.

“The newest and most surprising thing here is that SNAP, which is not a healthcare program, nevertheless seems to have an effect on healthcare costs,” Berkowitz said by email.

On average, SNAP benefits amount to about $129 a month per person, or about $1,548 a year, the study authors note.

Participants in the study had annual income below 200 percent of the federal poverty level, or about $24,000 for an individual or roughly $49,000 for a family of four.

People who enrolled in SNAP tended to be younger, about 40 years old on average, compared to 44 for individuals who hadn’t joined the food assistance program.

SNAP participants were more likely to be disabled and either be uninsured or have coverage through government health programs like Medicaid or Medicare.

There wasn’t much difference in annual health spending based on SNAP participation when researchers only accounted for two factors that can influence medical costs – age and gender. The difference was much more pronounced, however, when researchers also considered race, region, insurance, education, income, disability and other medical problems. When all of those factors were taken into account, SNAP enrollees had average annual health spending that was $1,409 less than people who didn’t participate in the program.

The study wasn’t a controlled experiment designed to prove whether or how SNAP benefits might directly contribute to lower health spending. It also didn’t examine how much of the spending was covered by insurance versus paid out-of-pocket by patients.

“These were not necessarily out-of-pocket costs incurred by the poor,” said Adam Drewnowski, director of the Center for Public Health Nutrition at the University of Washington in Seattle.

SNAP enrollment is associated with reduced spending on health care for low-income American adults, but not necessarily reductions in out-of-pocket spending by those individuals, Drewnowski, who wasn’t involved in the study, said by email.

It’s also possible that some of the reduced spending associated with SNAP is due to Medicaid coverage that restricts what medical services people can receive, said Tamara Dubowitz a nutrition researcher at RAND Corporation in Pittsburgh who wasn’t involved in the study.

“If there are fewer services covered, we may see less spending,” Dubowitz said by email.

However, improved food security can lead to more stable household finances as well as improved health and wellbeing for everyone in the household, Dubowitz added.

“It’s still unclear to what extent SNAP helps people afford healthier foods and a healthier diet versus the extent to which SNAP would help with economic stability of the household and less stress for other essential expenses,” Dubowitz said.

SOURCE: bit.ly/2jWTJZm JAMA Internal Medicine, online September 25, 2017.