Olive Oil Consumption Linked to CVD Benefits in the US

Higher olive oil intake is associated with a lower risk of coronary heart disease and cardiovascular disease in the United States, new observational data show. That’s important, say study authors, because olive oil consumption is typically much less in the US, where saturated fats and other plant-based unsaturated fats play a larger role in the diet. It’s also understudied on this side of the Atlantic.

There have been so many studies showing that olive oil is beneficial for preventing cardiovascular disease, but these have mainly involved European and Mediterranean populations, with no previous studies showing a similar association in the US population, where the intake of olive oil is much lower, Marta Guasch-Ferré, PhD (Harvard TH Chan School of Public Health, Boston, MA), told TCTMD.

Guasch-Ferré presented the findings March 5, 2020, at the American Heart Association’s EPI-Lifestyle 2020 Scientific Sessions; the paper was simultaneously published in the Journal of the American College of Cardiology.

Researchers extracted information on olive oil consumption from the diet questionnaires completed at baseline and every 4 years by 61,181 women in the Nurses’ Health Study and 31,797 men in the Health Professional’s Follow-up Study. After adjusting for demographics, Southern European/Mediterranean ancestry, a wide range of cardiovascular risk factors, and use of cardiovascular medications, investigators found that subjects consuming more than half a tablespoon per day (>7 g/day) had a 14% lower risk of cardiovascular disease and an 18% lower risk of coronary heart disease over 24 years of follow-up. No link was seen between olive oil consumption and stroke.

Speaking with TCTMD, Guasch-Ferré pointed to additional novel findings for this US cohort. For one, she said, there appeared to be important benefits to consumers if olive oil replaced approximately 5 g/day of margarine, butter, mayonnaise, or dairy fat; however, there was no difference between the benefits associated with olive oil consumption and those associated with intake of other nontropical, plant-based oils. 

“The main message is that our results provide support for the recommendations to replace saturated fats and animal fat with unsaturated olive oil or other types of unsaturated fats,” she said. 

The Post-PREDIMED Era

PREDIMED was the renowned Spanish diet study that established that a Mediterranean diet supplemented with additional extra virgin olive oil reduced major cardiovascular events by 31% as compared with a control diet in which fat restriction was advised. In that trial, participants in the intervention arm consumed between 32 to 50 g of extra-virgin olive oil per day. By contrast, in this retrospective study, mean olive oil intake was 12 g/day and the quality/variety of the olive oil was unknown.

But PREDIMED stoked controversy after it was first published in 2013 in the New England Journal of Medicine, then retracted and republished in 2018 following revelations that trial randomization had not gone as intended; other researchers have raised concerns about the whether the trial results, as a whole, can therefore be trusted.

Asked if the controversy that has arisen in the wake of PREDIMED’s retraction and republication has tarnished the thinking about olive oil for CVD prevention, Guasch-Ferré—who has co-authored multiple PREDIMED analyses since its original publication—dismissed the question, stressing that the trial’s only faults were related to randomization, which has no bearing on the current study, given the retrospective, observational nature of this new research.

Moreover, multiple reanalyses of PREDIMED have confirmed the primary findings, she noted. The only important point relating to PREDIMED for the current study is that the benefits in the US were seen with olive oil amounts as low as 12 g/day, which may indicate a threshold affect, she said. As the authors note in their paper, though, several studies have pointed to an inverse association between olive oil consumption and cardiovascular benefits: in PREDIMED, secondary analyses suggested that every 10-g increase in olive oil was associated with reductions in CVD and CVD mortality of 13% and 16%, respectively.

Olive oil’s benefits may be partly explained by the replacement of saturated fats with unsaturated oil, a recommendation also set out in a recent scientific advisory on dietary cholesterol from the American Heart Association. However, Guasch-Ferré also stressed that benefits integral to olive oil can’t be discounted, in particular high oleic acid content, which the authors note is less susceptible to oxidation than other more unsaturated fatty acids.

“It has also been observed that olive oil can have favorable effects on endothelial dysfunction, hypertension, inflammation, insulin sensitivity, and diabetes,” the authors conclude.

Commenting on the study for TCTMD, Penny Kris-Etherton, RN, PhD (Pennsylvania State University, University Park, PA), chair of the American Heart Association’s Lifestyle and Cardiometabolic Health Council, pointed out that the PREDIMED authors redid their analyses removing any patients randomized incorrectly in the trial. “I think their findings stand,” she said. “Both the olive-oil group and the mixed-nuts group had a significantly reduced risk of cardiovascular disease.”

A key outstanding question was whether these results could be extended to a US population, she continued, since it’s not clear from this study what else the participants were eating.

“I think what we have to do now is be careful what we tell Americans,” she said. “If they hear olive oil is good, they need to know that doesn’t mean dousing your food with olive oil and continuing to eat the same way Americans typically eat.”

Any benefits intrinsic to olive oil would need to be coupled, she said, with reductions in the types of fats typically consumed in higher quantities by Americans than are typically consumed in Spain.