If you love to drizzle a bit of olive oil on your salad, a new study suggests a side benefit to that tasty fat: a lower risk of heart disease.
The research, funded by the National Institutes of Health, found that people who had more than half a tablespoon of olive oil daily had a 21% lower risk of heart disease.
And, if you replace a teaspoon of butter, margarine or mayonnaise with the same amount of olive oil, your risk of heart disease and stroke may drop by 5%, the study found.
"The take-home message from our study is that our results provide recommendations to replace saturated animal fats (like butter) with unsaturated plant oils for the prevention of cardiovascular disease," said the study's lead author Marta Guasch-Ferre. She's a research scientist at Harvard T.H. Chan School of Public Health, in Boston.
How might olive oil help your heart?
Guasch-Ferre said olive oil is high in oleic acid, a healthy fatty acid associated with a lower risk of heart disease. Olive oil also has healthy properties linked to lower cholesterol levels and less inflammation, she explained.
Olive oil is a key component of the Mediterranean diet, which has been touted for its heart-protective properties. The Mediterranean diet consists of a lot of plant-based foods, fish and healthy fats, such as olive oil. But the researchers said studies haven't looked at the use of olive oil in a typical American diet.
To examine that, the investigators looked at nearly 100,000 men and women who participated in long-term studies from 1990 to 2014. Guasch-Ferre said the researchers collected information on lifestyle factors every two years, and detailed diet information every four years.
People who had more than a half-tablespoon a day of olive oil had a 15% reduced risk of any type of cardiovascular disease, and a 21% lower risk of coronary heart disease, specifically. And, greater olive oil intake lowered the risk even more, Guasch-Ferre said. But researchers don't know if there's an upper limit where olive oil's benefits would stabilize or drop, she noted.
Replacing a teaspoon of butter, margarine or mayonnaise with olive oil lowered the risk of any type of cardiovascular disease by 5% and the risk of coronary heart disease by 7%. The researchers pointed out that in the 1990s, margarines contained a substantial amount of unhealthy trans fatty acids. These results may not apply to today's vegetable oil-based margarines, they said.
When the researchers looked at stroke risk alone, they didn't find an impact from using olive oil.
They also used statistical models to see if other plant oils -- corn, canola, safflower and soybean -- might have benefits similar to olive oil, and they did.
Guasch-Ferre said researchers didn't look at the specific types of olive oil, such as virgin, extra virgin, cold-pressed or light. But previous research has suggested that extra virgin olive oil may provide more benefits, because it gets less processing.
Dietitian Jill Ashbey-Pejoves, chief clinical dietitian at Northern Westchester Hospital in Mount Kisco, N.Y., said this study confirms what has already been known.
"Replacing saturated animal fat with a plant-based fat is a positive dietary step," she said.
But, Ashbey-Pejoves added that this study wasn't designed to prove a cause-and-effect relationship. It could only find a potential link.
Still, she noted, "The more plant-forward your diet is, the more whole foods you eat, the better, especially for your cardiovascular disease risk."
Guasch-Ferre is scheduled to present the study's findings Thursday at an American Heart Association meeting in Phoenix. Findings presented at meetings are typically viewed as preliminary until they've been published in a peer-reviewed journal.
Read more about healthy oils from the American Heart Association.