University of Florida study suggests that "less may be better" when it comes to olive oil consumption

As a staple of plant-based diets such as the Mediterranean diet, olive oil has been widely praised for its ability to reduce the risk of heart disease. However, a study recently published by the University of Florida suggests that other elements of this diet could play an even bigger role in delivering health benefits.

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The Recipe for Heart Health study is the result of a collaboration between researchers from the UF/IFAS Department of Food Sciences and Human Nutrition , the UF Division of Cardiovascular Medicine , and the National Institute of Diabetes and Digestive and Kidney Diseases . Published in the Journal of the American Heart Association, the nine-week study followed 40 adults ages 18 to 79 over 11 months. Participants had a variety of health factors that put them at risk for cardiovascular disease.

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During the study, all participants followed whole-foods, plant-based vegan diets. They were randomly assigned to consume either a "low" amount (less than a teaspoon) or a "high" amount (4 tablespoons) of extra virgin olive oil (EVO) each day for four weeks. After a one-week "cleanse" period, participants switched amounts and followed the other EVO regimen for another four weeks.

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Cooked olive oil can produce inflammatory compounds depending on the temperature, so study participants were instructed to consume raw olive oil. Many added it to salad dressings and sauces. Participants abstained from eating animal products and highly processed and refined foods, opting instead to consume whole fruits, vegetables, legumes, whole grains, nuts and seeds. Although researchers encouraged the consumption of nutritionally balanced meals, they did not control for portion size or caloric composition of meals.

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Neither diet was low-fat; participants got at least 30 percent of their energy from dietary fat. In contrast, on a typical low-fat diet, fat would contribute 10 to 15 percent of total energy, said Andrea Krenek, senior author of the study and a registered dietitian nutritionist in the UF/IFAS Department of Food Sciences and Human Nutrition.

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During the high EVOO phase, participants obtained most of their dietary fat from EVOO. In contrast, during the low EVOO phase, fats came primarily from whole, unrefined plant sources, such as avocados, nuts, seeds, and olives.

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Compared to baseline levels, consuming both high and low amounts of EVOO resulted in decreased levels of LDL cholesterol, known as “bad” cholesterol and associated with heart disease. However, participants experienced more significant reductions in LDL cholesterol after following the low EVOO regimen for four weeks. 

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The order in which participants followed the regimens was equally significant. Those who started on the high-VOE regimen and then switched to the low-VOE regimen experienced a decrease in LDL cholesterol levels. In contrast, participants who started on the low-VOE regimen and switched to the high-VOE regimen saw an increase in their LDL levels compared to their levels at the end of the low-VOE phase. 

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“This study suggests that while a diet based on whole plant foods with or without extra virgin olive oil may reduce heart disease risk factors compared with a standard omnivorous diet, lower amounts of extra virgin olive oil, along with other sources of whole grain dietary fat, may lead to greater reductions in risk,” Krenek said.

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Focusing on whole, plant-based foods and limiting those that may increase risks, such as red and processed meats, added sugars and saturated fats, likely plays a more significant role in the benefits of plant-based diets than consuming EVOO alone, she explained.

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Krenek also mentioned that his team plans to use the data from this study to develop additional research on cooking, diet quality, mood and quality of life.

 

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