Increasing intake of polyunsaturated fats may help decrease heart disease deaths

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In 2010, more than 700,000 heart disease deaths were estimated to be due to eating too little n-6 polyunsturated fats (PUFA), more than 250,000 were due to excess consumption of saturated fats (SFA) and more than 500,000 were due to excess consumption of trans fats (TFA), according to a recently published modeling study.

Between 1990 and 2010, the estimated proportional coronary heart disease mortality for nonoptimal n-6 PUFA and SFA consumption decreased by 9 percent and 21 percent, respectively. Meanwhile, the estimated proportional coronary heart disease mortality for nonoptimal TFA consumpton increased by 4 percent during that same time period.

Lead researcher Qianyi Wang, ScD, of the Harvard T.H. Chan School of Public Health in Boston, and colleagues published their results online in the  Journal of the American Heart Association on Jan. 20.

“Worldwide, policymakers are focused on reducing saturated fats,” Dariush Mozaffarian, MD, DrPH, senior study author and dean of the Tufts Friedman School of Nutrition Science & Policy in Boston, said in a  news release. “Yet, we found there would be a much bigger impact on heart disease deaths if the priority was to increase the consumption of polyunsaturated fats as a replacement for saturated fats and refined carbohydrates, as well as to reduce trans fats.”

Previous research found that higher intakes of TFA and SFA instead of n-6 PUFA were associated with an increased risk of coronary heart disease, whereas higher intake of PUFA replacing either SFA or carbohydrate was associated with a lower risk of coronary heart disease.

In this Bayesian hierarchical model, the researchers estimated the mean intake levels of dietary SFA, n-6 PUFA and TFA in 24 age and sex subgroups within 186 countries in 1990 and 2010. The data came from dietary surveys, United Nations food balance sheets and industry sales data for TFA and represented 3.8 billion adults.

In 2010, the national mean intakes in the 186 nations ranked from 1.2 percent to 12.5 percent for n-6 PUFA, 2.3 percent to 27.5 percent for SFA and 0.2 percent to 6.5 percent for TFA.

In addition, 711,800 deaths worldwide (10.3 percent of the total global coronary heart disease mortality) were estimated to be attributed to insufficient n-6 PUFA consumption in place of carbohydrates or SFA. Of those deaths, 45 percent occurred prematurely and 43 percent occurred among women. The absolute attributable mortality was higher at older ages compared with younger ages, while attributable proportional coronary heart disease mortality was higher at younger ages versus older ages.

An estimated 250,900 deaths (3.6 percent of the total global coronary heart disease mortality) were attributable to excess SFA intake in place of n-6 PUFA, while an estimated 537,200 deaths (7.7 percent of the total global coronary heart disease mortality) were attributable to excess TFA consumption.

“People think of trans fats as being only a rich country problem due to packaged and fast-food products,” Mozaffarian said. “But, in middle and low income nations such as India and in the Middle East, there is wide use of inexpensive, partially hydrogenated cooking fats in the home and by street vendors. Because of strong policies, trans fat-related deaths are going down in Western nations (although still remaining important in the United States and Canada), but in many low- and middle-income countries, trans fat-related deaths appear to be going up, making this a global problem.”

The researchers noted that in 80 percent of nations, n-6 PUFA-attributable coronary heart disease burdens were at least two times as high compared with SFA-attributable burdens.

“This suggests that focus on increasing healthful n-6–rich vegetable oils may provide important public health benefits,” they wrote.

The researchers cited a few limitations of the study, including that the estimates were less certain in some regions than others. In addition, they evaluated TFA based on dietary surveys, blood TFA levels and industry sales data on partially hydrogenated oils and packaged foods because few national surveys assessed TFA. Further, they did not identify modification effects of cardiometabolic risk factors except for age.