Study Examines Heart Health Effects of Reducing Extra Virgin Olive Oil Consumption

Scientists at the University of Florida, USA, have conducted a randomized crossover trial to examine the cardiometabolic effects of extra virgin olive oil as part of a whole-food, plant-based vegan diet.

The trial's findings were published in the Journal of the American Heart Association.

Low-fat, whole-food, plant-based diets emphasize unrefined foods and limit processed products, refined grains, added sugars, and oils, including restricting vegetable oil fat intake to less than 10%-15% of energy intake. The Mediterranean diet, while also plant-based, includes extra virgin olive oil (EVOO) as the main fat source, with moderate seafood, poultry, and dairy consumption, and up to 35%-40% of energy intake from vegetable oils.

To compare the cardiometabolic effects of EVOO within a low-fat, whole-food, plant-based diet, scientists at the University of Florida have conducted a randomized crossover trial called "The Recipe for Heart Health trial."

The study involved 40 adults aged 18 to 79 with a cardiovascular disease risk of 5% or higher. They were randomly assigned to follow one of two whole-food, plant-based diets for four weeks each. One diet included four tablespoons of extra virgin olive oil daily, while the other included less than one teaspoon daily. Participants switched diets after a one-week break.

To help them stick to the diets, participants attended weekly online cooking classes led by a dietitian/chef. The researchers considered age, sex, and weight changes when analyzing the effects of the two diets on LDL cholesterol and other heart health markers like blood lipids, blood sugar levels, and inflammation.

The study measured blood metabolite levels after each 4-week diet period and found that both diets significantly reduced LDL cholesterol, with no major differences between the high- extra virgin olive oil and low- extra virgin olive oil diets. Both diets also similarly lowered total cholesterol, apolipoprotein B, HDL cholesterol, glucose, and high-sensitivity C-reactive protein (CRP) levels compared to the start. However, during the first 4-week period, the low- extra virgin olive oil diet reduced LDL cholesterol, total cholesterol, HDL cholesterol, apolipoprotein B, and glucose levels more than the high- extra virgin olive oil diet. These differences evened out in the second 4-week period.

When looking at the order in which the diets were followed, LDL cholesterol dropped significantly in those who went from high to low extra virgin olive oil, but increased in those who went from low to high extra virgin olive oil. The low to high extra virgin olive oil sequence also raised total cholesterol, HDL cholesterol, and glucose levels. Both diets led to weight loss, but the low- extra virgin olive oil diet resulted in more significant weight reduction.

The findings revealed that both high and low extra virgin olive oil intake reduced blood LDL-C levels, even though total fat made up 48% of total energy during the high-EVOO period and 32% during the low- extra virgin olive oil period.

Reference: Krenek AM. 2024. Recipe for Heart Health: A Randomized Crossover Trial on Cardiometabolic Effects of Extra Virgin Olive Oil Within a Whole‐Food Plant‐Based Vegan Diet. Journal of the American Heart Association. https://www.ahajournals.org/doi/10.1161/JAHA.124.035034