More of this, less of that to help your heart

We know that reducing the amount of saturated fat in your diet is a good way to help improve your cholesterol scores. We also know that poor cholesterol scores put you at higher risk for heart attacks and stroke. However, the available evidence from randomized controlled trials has not specifically shown that reducing saturated fat actually leads to fewer cardiac events such as heart attacks and stroke.

On the other hand, we do know that getting more polyunsaturated fatty acids, like those found in fish or vegetable oils, helps improve cholesterol scores. What we need is a study that looks at whether replacing saturated fats with unsaturated fats means fewer cardiac events and not just improved cholesterol scores.

A team out of Harvard Medical School and their School of Public Health has gathered information from eight previous studies that essentially does just that (PLOS Med 2010;7(3):e1000252). They identified eight studies done around the world that included over 13,000 people. Each study was required to have the following characteristics:

• Subjects were randomly assigned to a group that increased their polyunsaturated fats or a control group that did not;
• Lasted at least one year;
• Reported how many heart attacks or sudden cardiac deaths occurred in the participants over the course of the study.

Overall, the control groups averaged between 4% and 6.4% of their daily calories per day from polyunsaturated fatty acids. (For a 1500-calorie diet, that would be between 60 and 96 calories per day.) The test groups, who increased their polyunsaturated fat intake, averaged between 8% and 20.7% of their daily calories from polyunsaturated fats. (Again, for a 1500-calorie diet, that would be between 120 and 310 calories per day.)

For all of the studies combined, the researchers found that those who increased their polyunsaturated fatty acids had an almost 20% decrease in their risk of a heart attack or stroke. Those who increased their intake the most had the most benefit: every increase of 5% of daily calories from polyunsaturated fatty acids meant a 10% reduction in risk. Further, the longer the participants maintained that higher amount of polyunsaturated fats in their diet, the lower their risk became.

What this means for you

Here are just a few foods that are high in polyunsaturated fatty acids: grapeseed oil, salmon, nuts and seeds. If you also decrease your saturated fat intake (often found in butter, fattier meats and dairy products), does that sound like the Mediterranean Diet to you? Find out more about the Mediterranean Diet at mds.culinarymedicine.org/mediterraneandiet.

First posted: March 24, 2010