The fatty acids have been linked to heart disease
New Yorkers fond of eating out in the last decade weren’t just saved from doing the dishes. Residents’ blood levels of artificial trans fats, which increase the risk of heart disease, dropped following a 2006 citywide policy that banned restaurants from using the fats.
Researchers analyzed blood samples of adult city residents from before and after the ban, taken as part of a health and nutrition survey that queried participants on their dining habits. The samples, 212 from 2004 and 247 from 2013–2014, revealed a drop from 49.2 to 21.3 micromoles per liter, suggesting that trans fat levels plunged by about 57 percent overall among New Yorkers.
For people who dined out frequently, the decrease was even greater: Levels of the fats declined by about 62 percent for New Yorkers who ate out four or more times per week, the team reports online February 21 in the American Journal of Public Health.
An estimated 1 in 5 city residents eats out that frequently, says study coauthor Sonia Angell, deputy commissioner of the New York City Department of Health and Mental Hygiene in Queens. “We think [the ban] has just been a win overall for New Yorkers … in particular for those who dine out more frequently.”
Blood levels of trans fatty acids declined in New York City residents from 2004 to 2014. While even people who rarely ate out saw a decrease, New Yorkers who ate out the most had the biggest drop. Their levels declined by about 62 percent, suggesting a 2006 ban on the fats in restaurant foods worked, researchers say.
Change in New Yorkers’ trans fatty acid levels (micromoles/liter), 2004 and 2014
Source: M. Wright et al/American Journal of Public Health 2019
Artificial trans fats, also called trans fatty acids, end up in foods like fried chicken and doughnuts, anything that is fried, baked or cooked in partially hydrogenated vegetable oils. The fats increase the amount of low-density lipoprotein, commonly known as “bad” cholesterol, in the body while lowering high-density lipoprotein, the “good” cholesterol.
Reducing artificial trans fats in the diet “decreases the risk of heart disease, and the study found definite decreases in consumption in people that ate out,” says Jennifer Pomeranz, a public health lawyer at New York University who was not involved in the study. “This is really a great success of local policy making.”
The estimated drop in the level of artificial trans fats in New Yorkers’ bloodstreams is similar to what happened nationally after the U.S. Food and Drug Administration mandated in 2006 that companies include artificial trans fats in food nutrition labels. A previous study found that from 1999 to 2010, there was a 54 percent decline in blood levels of the fats in a sample of U.S. adults.
That labeling change likely contributed to the lower amounts found in New Yorkers, the researchers say. The team reports that levels of the fats dropped by about 51 percent in New Yorkers who ate out the least. But the fact that residents who ate out more frequently had the biggest drop indicates that the ban had its own impact beyond the national action, Angell says.
A 2 percent increase in calories from trans fatty acids in a person’s diet is associated with a 23 percent rise in the occurrence of coronary heart disease, a previous analysis reported. A 2017 study of the health effects of trans fatty acid restrictions found that those locations that enacted a ban on use by restaurants had fewer hospitalizations for heart attacks and strokes (SN: 5/13/17, p. 8).
A national policy removing partially hydrogenated oils from processed foods, mandated by the FDA, went into effect in June 2018.
Editor's note: This story was updated February 27, 2019, to correct the effective date of the national policy on partially hydrogenated oils in processed foods. It was June 2018, not July.
M. Wright et al. Impact of a municipal policy restricting trans fatty acid use in New York City restaurants on serum trans fatty acid levels in adults. American Journal of Public Health. Published online February 21, 2019. doi:10.2105/AJPH.2018.304930.
H.W. Vesper et al. Plasma trans-fatty acid concentrations in fasting adults declined from NHANES 1999–2000 to 2009–2010. American Journal of Clinical Nutrition. Vol. 105, May 2017, p. 1063. doi:10.3945/ajcn.116.141622.
A. Cunningham. Rules restricting artificial trans fats are good for heart health. Science News. Vol. 191, May 13, 2017, p. 8.
B. Brookshire. How trans fats oozed into our diet and out again. Science News Online, July 29, 2015.
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