Research demonstrates that participation in the Supplemental Nutrition Assistance Program (SNAP) lowers the risk of household food insecurity. However, little is known about the causal relationship between SNAP and other health outcomes. Researchers used data from the Centers for Disease Control and Prevention's National Health Interview Survey and National Death Index to examine the causal relationship between SNAP participation and the probability of premature mortality from 1997 to 2011.

They controlled for possible confounding factors, including self-reported health status and income at the time of the National Health Interview Survey. They first examined all-cause mortality and then focused on a subsample of households with an income-to-needs ratio below 200% of the federal poverty level, as well as respondents who would be younger than age 65 at the end of the study period.

The risk of all-cause mortality in the full sample would be 7.09% if nobody participated in SNAP, the authors conclude, compared with 6.29% if everyone participated, an average treatment effect of 0.8 percentage points. In the full sample of participants younger than age 65, the risk of mortality would be 2.33% if nobody participated in SNAP compared with 0.79% if everyone participated, an average treatment effect of approximately 1.55 percentage points. The difference in predicted mortality between SNAP participants and nonparticipants would be even greater in the full and low-income samples, ranging from 0.34 to 2.90 percentage points in models controlling for income and health.

The authors point out that SNAP may have effects on outcomes other than mortality, which may be more sensitive in the short term. In addition, because mortality was examined for fewer than 15 years, the authors note they couldn't draw conclusions about the effect on life expectancy of receiving SNAP benefits in early or middle life.