In 2007, some counties of New York State began restricting the use of trans-fatty acids in sold food. The rules attracted both praise and condemnation for limiting people's rights to make their own choices. Those debates have been fanned by the lack of evidence of effectiveness. A paper in JAMA Cardiology indicates that, whatever you think of the principle, the restrictions probably work.
Trans-fatty acids, often called trans fats, are rare in nature but common in packaged foods and fried meals from fast food outlets. They have been shown to worsen the ratio of “bad” to “good” cholesterol and consequently increase one's risk of heart disease.
During his three terms as mayor of New York City, Michael Bloomberg attempted to transform the health of the city by attacking known causes of disease. Smoking in public was limited, but an attempt to downsize soft drinks at cinemas was overturned in court. As part of the program, food vendors were forced to use alternatives to trans fats. Several neighboring counties followed soon after.
Measuring the effectiveness of public health initiatives is hard, however. Many factors contribute to cardiovascular ill-health. First author Dr Eric Brandt of Yale University attempted to tease out the influence of the restrictions by looking at hospitalization rates for people living in 11 counties where trans fats were regulated and 25 where they were not.
Once three or more years had passed from the restrictions coming into force, people living in the counties where they applied had a 6.2 percent decline in hospitalizations for heart conditions compared to those where the restrictions were not implemented. A small difference observed in stroke rates was not statistically significant. One for myocardial infarctions, commonly known as heart attacks, was even larger at 7.8 percent.
“It is a pretty substantial decline,” Brandt said in a statement. “Our study highlights the power of public policy to impact the cardiovascular health of a population.”
The measurements do not necessarily prove the trans fat restrictions were effective. Hospitalizations for heart conditions fell across the board at this time, and the greater improvement in certain counties might be explained by other factors, such as a greater decrease in smoking. However, Brandt specifically chose the unrestricted counties as ones that would provide the best comparisons, and got similar results when he limited the analysis to areas outside New York City in an effort to eliminate alternative explanations such Bloomberg's other interventions.
Unsurprisingly, given the potential confounding factors, the study hasn't convinced everybody. However, given the impracticality of conducting randomized control trials on the topic, it may be the best we get before the Food and Drug Administration implements controls on trans fats across the United States next year.