Olive oil vs. butter: How does the type of fat consumed affect cardiovascular risk factors? Original paper

In this randomized crossover trial, the consumption of extra-virgin olive oil, compared to butter, improved blood pressure and blood lipids.

The effect of extra virgin olive oil (EVOO), compared to butter, on cardiovascular risk factors.

The primary outcome was the change in systolic blood pressure (measured via 24-hour ambulatory blood pressure monitoring). The secondary outcomes were diastolic blood pressure, total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides.

32 men (average age of 31; average BMI of 24) of either Chinese or European origin and without apparent health conditions.

In this 2-week randomized crossover trial, the participants received either 30 milliliters of EVOO or 30 grams of butter daily. The participants were instructed to replace their usual lunch with cream of potato or leek soup mixed with EVOO or butter, a piece of fruit, and one slice of medium-sized white bread. There was a 2-week washout period between interventions.

Dietary intake was examined using 3-day dietary records. Additionally, the participants recorded their diets during the first 2-week intervention and were asked to repeat this diet during the subsequent intervention.

Compared to the butter intervention, 24-hour systolic blood pressure was 4.3 mmHg lower during the EVOO intervention. In subgroup analysis by ethnicity, the difference in systolic blood pressure between the interventions was significant for participants of Asian origin, but not for participants of European origin.

Regarding blood lipids, levels of total cholesterol and LDL-C were 8 and 6.5 mg/dL lower, respectively, during the EVOO intervention compared to the butter intervention. Subgroup analysis indicated a stronger effect of EVOO on reducing LDL-C levels in participants of European origin.