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Olive in olive oil linked with cardiovascular health

Extra Virgin Olive Oil Protects the Heart and Slashes Breast Cancer Risk

Extra virgin olive oil retains polyphenols that favorably interact with the gut microbiota to lower cardiovascular risk factors.

Scientifically reviewed by: Dr. Crystal M. Gossard, DCN, CNS, LDN, in August 2023. Written by: Cheryl Hopkins.

All olive oil isn’t the same.

There are different grades of olive oil available, with very different health properties. Unfortunately, it’s not always easy to tell which olive oil you are getting. (Hint: extra virgin olive oil is the healthy kind you want.)

In a 2019 published study, mice fed extra virgin olive oil had significantly lower total cholesterol and blood pressure, and a higher ratio of HDL (good) cholesterol to LDL (bad) cholesterol, compared to mice fed refined olive oil.1

The two types of olive oil examined in this mouse study might be sold side-by-side in stores, but it is a mistake to view them equally.

The study showed that eating refined olive oil led to similar adverse results as ingesting butter.1

One reason is the way different grades of olive oil are extracted, and their effects on gut microbiota. What surprised scientists was learning how extra virgin olive oil interacts with host microbiota to improve heart health.

Why Extra Virgin Olive Oil is Better


Olive oil has widely publicized health benefits compared to other vegetable oils and animal fats.2,3 It is a staple of the highly recommended mediterranean diet.

But not all olive oils are the same.

When olives are freshly pressed to extract the oil, the first material that’s produced, without any chemical processing, is extra virgin olive oil.1,4,5

In this instance, the term “virgin” means the olive oil is unprocessed.

It’s rich in polyphenols, plant nutrients with a wide range of health benefits, and tocopherols, variations on vitamin E that provide protection against oxidative stress.1

Although these compounds are the source of much of extra virgin olive oil’s health benefits, high amounts can result in strong or biting flavors that are not to everyone’s taste.6

Refined olive oil (the label may simply say “olive oil”, but it cannot say “extra virgin olive oil”) has been subjected to chemical treatments to make it nearly flavorless, odorless, and colorless. Manufacturers may then add back a small amount of extra virgin olive oil to impart a little flavor.

The refining process does more than strip out the flavor, color, and aroma—it also strips out practically all of the polyphenols and tocopherols, leaving the oil devoid of the most beneficial compounds.4,5

The polyphenol content of extra virgin olive oil ranges between 150 mg/kg to 400 mg/kg, while that of refined olive oil is just 0 mg/kg to 5 mg/kg. This makes a huge difference in the health benefits of the two types of oil.1,7

Comparing Extra Virgin and Refined Olive Oil

A group of Spanish scientists compared the effects of extra virgin and refined olive oil on body weight, blood pressure, plasma insulin and lipid profiles, and other factors.1

The researchers fed a different diet to each of four groups of mice:1

  • Standard, grain-rich mouse food, in which 8% of calories came from fat,
  • Standard mouse food with extra virgin olive oil added, for a high-fat diet with 38% more calories, 35% coming from fat,
  • Standard food enriched with refined olive oil to the same level of calories and fat, and
  • Standard food enriched with butter to the same fat and calorie level.

At the end of 12 weeks, systolic blood pressure, lipids, and other factors that contribute to the risk of cardiovascular and metabolic diseases were measured. Feces were also collected for microbiome analysis, and blood samples were taken for biochemical analysis.

Surprising Findings

The results of this study showed a significant impact on risk factors for disease—and changes in gut microbiota that suggested reasons for those changes.1

Body weight, systolic (top number) blood pressure, and plasma insulin were significantly higher in the butter-fed group. That makes sense. Butter is an animal fat high in saturated fats and calories.

But here’s where it gets surprising: Mice fed the low-fat standard diet and the extra virgin olive oil diet had significantly lower total cholesterol than the mice fed butter or refined olive oil, even though there is no cholesterol in refined olive oil.

Extra virgin olive oil produced the highest ratio of HDL (good) cholesterol to LDL (bad) cholesterol, even higher than the lower-calorie standard diet. The animals who ate refined olive oil had HDL/LDL ratios similar to those of mice fed butter.

Animals fed extra virgin olive oil also had lower blood pressure than any other group.1

How the Gut Microbiota are Involved

The scientists also examined the different effects on gut microbiota composition.

The impact of the dietary fat source on gut microbiota composition was substantial—in ways that correlate with many of the common risk factors for degenerative diseases.1

There were significant differences in the levels of different gut bacterial families among the groups ingesting extra virgin olive oil, refined olive oil or butter.

One bacterial group in particular, called Desulfovibrionaceae, was significantly higher in those fed refined olive oil and butter, compared with those given extra virgin olive oil and the standard diet.1

These intestinal bacteria are associated with high levels of inflammation and impaired immune function—risk factors for metabolic syndrome, cardiovascular disease, and autoimmune disorders.8-11

Two other bacterial families were elevated in mice fed refined olive oil compared with the other diets.1 Both have negative associations with human health, including cancers and inflammatory diseases.12-20

Two beneficial bacterial families were found in highest abundance in animals fed the extra virgin olive oil. Both of them are associated with improved metabolic functions, including lowering levels of insulin and leptin.1,21

Woman on bike

Large Human Trial Demonstrates Extra Virgin Olive Oil Reduces Cardiovascular and Breast Cancer Risks

Results of a large clinical trial published in two prestigious medical journals, JAMA Internal Medicine and the New England Journal of Medicine, demonstrate that a diet supplemented with extra virgin olive oil provides health benefits.22,23

The PREDIMED study enrolled adults aged 55 to 80 who were considered at high risk for cardiovascular disease based on various factors.

Participants were randomized to three different groups. Two of the groups were assigned to a Mediterranean diet, one with supplemental extra virgin olive oil (at least 4 tbsp) and the other supplemented with mixed nuts. The third group was assigned to a control, low-fat diet.

Over almost five years of follow-up, cardiovascular outcomes including heart attack, stroke, and death from any cardiovascular cause, were noted. The Mediterranean diet groups had a significantly lower rate of negative cardiovascular outcomes. This association was particularly strong for the supplemental extra virgin olive oil group, which had a 31% reduction in risk for cardiovascular disease outcomes compared to the control diet group.22

The researchers also observed the rate of new breast cancer in the women enrolled. Here, too, the diet supplemented with extra virgin olive oil was most protective, reducing rates of breast cancer by nearly 70% compared to the control diet. Interestingly, the group that supplemented with mixed nuts did not show a significant benefit in terms of breast cancer risk.23

The study’s authors report that this was the first human trial to find a beneficial effect of a dietary intervention on breast cancer risk. Together, these results suggest that a Mediterranean diet with supplemental extra virgin olive oil is protective against both cardiovascular disease and breast cancer in older adults with existing risk factors.


This new preclinical mouse study adds support for the benefits of extra virgin olive oil.

Compared with butter and refined olive oil, extra virgin olive oil improved systolic blood pressure, insulin levels, cholesterol, and HDL/LDL cholesterol ratios. Those all lead to lower risks for cardiovascular and metabolic diseases.

The study also showed a likely reason: A diet rich in extra virgin olive oil favorably modulates bacterial families associated with multiple diseases, while boosting microbes with protective effects.1

Human findings show supplemental extra virgin olive oil can markedly reduce cardiovascular and breast cancer risks in those following a Mediterranean-type diet.

Health-conscious people should aim to use extra virgin olive oil in their diets, and not refined olive oil or butter.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.


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