People living in areas that restrict trans fats in foods had fewer hospitalisations for heart attack and stroke compared to residents in areas without restrictions, according to a new study conducted by researchers at the University of Chicago Medicine and Yale School of Medicine.
“The results are impressive, given that the study focused on trans fatty acid bans in restaurants, as opposed to complete bans that included food bought in stores,” said senior author Dr Tamar S Polonsky, a general cardiologist and assistant professor of medicine at the University of Chicago. “If we enact a more complete restriction on trans fatty acids, it could mean even more widespread benefits for people long term.”
Trans fatty acids, or trans fats, are commonly found in fried foods, chips, crackers and baked goods. Eating even minimal amounts is linked to a greater risk of cardiovascular disease, the leading cause of death worldwide. Some communities – most notably New York City – have eliminated the use of trans fats in restaurants and eateries in recent years.
To study the impact of restricting trans fats, researchers compared outcomes for people living in New York counties with and without the restrictions. Using data from the state department of health and census estimates between 2002 and 2013, the researchers focused on hospital admissions for heart attack and stroke. They found that three or more years after the restrictions were implemented, people living in areas with the bans had significantly fewer hospitalisations for heart attack and stroke when compared to similar urban areas where no limits existed. The decline for the combined conditions was 6.2%.
“It is a pretty substantial decline,” said lead author Dr Eric Brandt, a clinical fellow in cardiovascular medicine at Yale School of Medicine. “Our study highlights the power of public policy to impact the cardiovascular health of a population.”
The US Food and Drug Administration approved a nationwide ban on partially hydrogenated oil in foods, which effectively will eliminate dietary trans fat when it goes into effect in 2018.
Current FDA labeling guidelines allow up to 0.49 grams of trans fat per serving to be labeled as 0 grams. According to lead author Brandt, this leaves consumers with the burden to scour labels for hidden trans fats.
“With the upcoming FDA regulation, people need not be so vigilant,” he said.
Importance: Trans-fatty acids (TFAs) have deleterious cardiovascular effects. Restrictions on their use were initiated in 11 New York State (NYS) counties between 2007 and 2011. The US Food and Drug Administration plans a nationwide restriction in 2018. Public health implications of TFA restrictions are not well understood.
Objective: To determine whether TFA restrictions in NYS counties were associated with fewer hospital admissions for myocardial infarction (MI) and stroke compared with NYS counties without restrictions.
Design, Setting, and Participants: We conducted a retrospective observational pre-post study of residents in counties with TFA restrictions vs counties without restrictions from 2002 to 2013 using NYS Department of Health’s Statewide Planning and Research Cooperative System and census population estimates. In this natural experiment, we included those residents who were hospitalized for MI or stroke. The data analysis was conducted from December 2014 through July 2016.
Exposure: Residing in a county where TFAs were restricted.
Main Outcomes and Measures: The primary outcome was a composite of MI and stroke events based on primary discharge diagnostic codes from hospital admissions in NYS. Admission rates were calculated by year, age, sex, and county of residence. A difference-in-differences regression design was used to compare admission rates in populations with and without TFA restrictions. Restrictions were only implemented in highly urban counties, based on US Department of Agriculture Economic Research Service Urban Influence Codes. Nonrestriction counties of similar urbanicity were chosen to make a comparison population. Temporal trends and county characteristics were accounted for using fixed effects by county and year, as well as linear time trends by county. We adjusted for age, sex, and commuting between restriction and nonrestriction counties.
Results: In 2006, the year before the first restrictions were implemented, there were 8.4 million adults (53.6% female) in highly urban counties with TFA restrictions and 3.3 million adults (52.3% female) in highly urban counties without restrictions. Twenty-five counties were included in the nonrestriction population and 11 in the restriction population. Three or more years after restriction implementation, the population with TFA restrictions experienced significant additional decline beyond temporal trends in MI and stroke events combined (−6.2%; 95% CI, −9.2% to −3.2%; P < .001) and MI (−7.8%; 95% CI, −12.7% to −2.8%; P = .002) and a nonsignificant decline in stroke (−3.6%; 95% CI, −7.6% to 0.4%; P = .08) compared with the nonrestriction populations.
Conclusions and Relevance: The NYS populations with TFA restrictions experienced fewer cardiovascular events, beyond temporal trends, compared with those without restrictions.
Eric J Brandt, Rebecca Myerson, Marcelo Coca Perraillon, Tamar S Polonsky