Olive Oil's Role in Vegan Diets for Heart Disease Risk under Scrutiny

Switching from an omnivorous diet to one rich in nuts, fruits, and vegetables is a common strategy for reducing body fat levels in individuals at risk of heart disease.

However, the inclusion of extra virgin olive oil (EVOO) in such diets might not always be beneficial, according to recent research.

A team of scientists from the University of Florida and the National Institute of Diabetes and Digestive and Kidney Diseases examined the health impacts of plant-based diets on individuals at risk of atherosclerotic cardiovascular disease (ASCVD).

While the Mediterranean diet, which includes EVOO, is often promoted for its heart health benefits, the study explored the effects of adding olive oil to a vegan diet.

The researchers recruited 40 adults, aged 18 to 79, to follow a carefully controlled vegan diet for eight weeks.

Participants spent four weeks on a diet that included four teaspoons of EVOO per day and another four weeks on a low EVOO diet without additional olive oil, with a one-week break between the two phases.

Both diets led to improvements in cardiometabolic profiles, including cholesterol, blood sugar, and inflammation levels, compared to pre-diet measurements.

Interestingly, the sequence in which the diets were followed affected LDL cholesterol levels.

When participants began with the high EVOO diet and then transitioned to the low EVOO diet, their LDL cholesterol, or 'bad' cholesterol, levels decreased.

Conversely, when the low EVOO diet was followed by the high EVOO diet, the reduction in LDL cholesterol was less pronounced.

The researchers suggest that the small amounts of saturated fat in EVOO might influence the liver's processing of LDLs, potentially leading to higher LDL levels in the blood.

"Decreased intake of extra virgin olive oil may yield increased lipid lowering than relatively greater consumption," the researchers noted in their published paper.

While the study accounted for variables like sex and body weight, it focused on participants at borderline to high risk for ASCVD, which can develop from excessive LDL cholesterol blocking the arteries.

The differences in LDL cholesterol reductions were relatively small, particularly when the low EVOO diet was followed second.

Nevertheless, the study confirmed that plant-based diets, with or without olive oil, are generally beneficial for heart health.

"Although both diets improved the metabolic phenotype, a low EVOO intervention may provide superior LDL‐C lowering in individuals at highest risk," the researchers wrote.

The findings suggest that limiting extra virgin olive oil may be worth considering for those at higher risk of heart disease.

Future research could explore this association in larger groups and over longer periods.

"Addition of extra virgin olive oil after consuming low amounts within a whole food, plant‐based diet may impede risk reduction," the researchers concluded.

"Consideration of optimal sources of dietary fats as well as quantity of extra virgin olive oil within a risk‐lowering vegan dietary pattern may vary depending on dietary context and risk level."