Olive Oil Archives - Health Tips From The Professor

Is Olive Oil Overrated?

September 24, 2024 by Dr. Steve Chaney

What Is The Truth About Olive Oil And You?

Author: Dr. Stephen Chaney

You may have seen headlines claiming that olive oil doesn’t deserve its “health halo”. It isn’t as healthy as many experts have claimed. It is overrated.

These headlines aren’t referring to the scandalous practice of selling “extra virgin” olive oil that contains cheaper oils. That is another topic for another day.

The headlines are claiming that, while the Mediterranean diet is healthy, it is fruits, vegetables, whole grains, legumes, and fish that make the Mediterranean diet healthy. Their claim is that olive oil has little to do with it.

To evaluate these claims I have reviewed the study (AK Krenek et al, Journal of the American Heart Association, Volume 13, Number 15:e035034, July 24, 2024) behind the headlines.

And to provide context, I have also reviewed another recent study (M Guasch-Ferre et al, Journal of the American College of Cardiology, Volume 79, Number 2, 2022).

How Were These Studies Done?

The two studies were very different:

The First Study used a randomized cross-over design to compare high and low olive oil diets.

In the randomized cross-over design participants were randomly assigned to one of the two diets at the beginning of the study. They followed that diet plan for 4 weeks. And after a one week “washout” they followed the other diet plan for 4 weeks. In this type of study each participant serves as their own control.

Study participants (50 obese participants, average age = 64, 75% women, 72% white, ≥ 5% risk of heart disease) were all eating a typical American diet.

Each of the experimental diets was a whole food plant-based diet, with comparable amounts of fruits, vegetables, whole grains, legumes, nuts, and seeds. Both diets were high in fiber, low in added sugar, and contained less than an ounce of animal products a day. In other words, the base diet was a healthy plant-based diet.

Participants in the high olive oil group were asked to add 4 tablespoons/day of extra virgin olive oil to their diet while participants in the low olive oil group were asked to restrict their olive oil intake to < 1 teaspoon/day.

No effort was made to control portion sizes or caloric intake. As we will see below, this was a major weakness of the study. As you might expect, fat intake was significantly greater for those on the high olive oil diet (49% of calories) compared to the low olive oil diet (32% of calories). Consequently, caloric intake was also significantly greater on the high olive oil diet.

All participants met with a dietitian/chef at the beginning of the study and were given access to online training programs and a dietitian hotline for questions. Dietary intake was measured by a 24-hour dietary recall 4-7 times prior to the study and 4 times during each diet period.

Fasting blood and urine samples were collected prior to the study and at the end of each 4-week diet period to measure biomarkers with possible predictive value for heart disease, such as LDL cholesterol.

The Second Study was a prospective cohort study using data obtained from 60,582 women in the Nurses Health Study and 31,801 men in the Health Professionals Follow-Up Study.

In a prospective cohort study a cohort or group of people (in this case, the 60,582 women and 31,801 men in the two studies) are followed over time (in this case for 28 years from1990 to 2018). The study then measures the association between some aspect of their diet and lifestyle (in this case the kind of fat in their diet) and health outcomes at the end of the study (in this case all-cause mortality, cardiovascular mortality, cancer mortality, neurodegenerative disease mortality, and respiratory disease mortality).

A strength of this study was that the diet of all participants was assessed every 4 years, which allowed the investigators to track changes in their diet over time. The intake of most fats was remarkably stable over the entire 28-year duration of the study.

However, as the bad news about margarine and the good news about olive oil entered the popular media, margarine consumption declined, and olive oil consumption increased. Because the investigators were able to track these changes over time, they were able to correct for them in their data analysis.

Is Olive Oil Overrated?

Results From The First Study: If we restrict ourselves to statistically significant observations, the results were as follows:

Switching from the baseline diet (typical American diet) to either the high olive oil or low olive oil diets for 4 weeks resulted in a significant decrease in total cholesterol, LDL cholesterol, HDL cholesterol, and blood glucose levels.

In this case, there was no statistically significant difference between the two diets.

However, when transitioning from the low olive oil diet to the high olive oil diet and from the high olive oil diet to the low olive oil diet, some statistically significant differences were observed.

For example, transitioning from the high olive oil diet to the low olive oil diet resulted in:

A 7% decrease in total cholesterol.

An 11% decrease in LDL-cholesterol.

A 2.2% decrease in HDL-cholesterol.

A 2% decrease in blood glucose levels.

And transitioning from the low olive oil diet to the high olive oil diet resulted in:

A 14% increase in total cholesterol.

A 14% increase in LDL-cholesterol.

A 15% increase in HDL-cholesterol.

A 17% decrease in blood glucose levels.

The authors of this study said, “Although both [whole food, primarily plant-based] diets improved [risk factors for heart disease], a low olive oil intervention may provide superior LDL-cholesterol lowering in individuals at highest risk [of heart disease]. Future studies are needed to determine if these short-term effects are sustainable and translate to improvements in cardiac outcomes…Nevertheless, a whole food primarily plant-based diet with relatively lower olive oil may be a useful tool for clinicians for improving cardiovascular risk compared with greater olive oil intake.”

The authors also went on to say, “…olive oil may not be the beneficial additive of a Mediterranean diet.”

Results From The Second Study:

Higher intake of olive oil (>0.5 tablespoons/day compared to ≤1 teaspoon/day) resulted in:

A 19% decrease in the risk of all-cause mortality. And when that was broken down by cause it amounted to:

- A 19% decrease in the risk of cardiovascular mortality.

- A 17% decrease in the risk of cancer mortality.

- A 29% decrease in the risk of neurodegenerative disease mortality.

- An 18% decrease in the risk of respiratory disease mortality.

In a substitution analysis calculating the effect of consuming 10 g/day of olive oil instead of 10 g/day of:

Butter resulted in a 14% decrease in the risk of all-cause mortality.

Margarine or dairy fat resulted in a 13% decrease in the risk of all-cause mortality.

Mayonnaise resulted in a 9% decrease in the risk of all-cause mortality.

Other vegetable oils had no effect on all-cause mortality.

Results were similar when the investigators looked at the effect of replacing fats with olive oil on mortality due to cardiovascular disease, cancer, neurodegenerative disease, and respiratory disease.

The authors of the second study concluded, “Higher olive oil intake was associated with lower risk of total and cause-specific mortality. Replacing margarine, butter, mayonnaise, and dairy fat with olive oil was associated with lower risk of mortality.”

How can we reconcile these conflicting viewpoints? Let me start by looking at the flaws in the first study. Then I will summarize the “truth” about olive oil based on what these two studies tell us.

Is The Study Behind The Headlines Misleading?

First let me summarize why I consider the study to be misleading. Then I will discuss why the headlines about the study are misleading.

Why The Study Is Misleading: The main conclusion of this study was that adding olive oil to a primarily plant-based diet increased the risk of heart disease. While this study is well-designed in some respects, it is flawed in others. I will summarize the flaws here:

Flaw Number 1: The authors rely on the relative effects of the high and low olive oil diets on LDL-cholesterol levels in predicting the effect of the two diets on heart disease risk. However, there is a major problem with this argument:

HDL-cholesterol levels move in the same direction. Both are decreased in the transition from the high olive oil to the low olive oil diet. Both are increased in the transition from the low olive oil to high olive oil diet. The ratio of HDL to LDL cholesterol changes very little, so it is almost impossible to predict what effect these changes will have on heart disease outcomes.

Flaw Number 2: This is related to the flaw I mentioned earlier. No effort was made to control portion size or caloric intake of participants on these diets. The high olive oil diet added 4 tablespoons of olive oil to the low olive oil diet. This significantly increased the fat and caloric intake of participants on the high olive oil diet.

Participants lost weight on both diets, but weight loss was significantly greater on the low olive oil diet. In their discussion, the authors admitted that the greater reduction in LDL-cholesterol on the low olive oil diet could have been due to the greater reduction in weight on that diet.

Flaw Number 3: I call this the “straw man” flaw. By adding 4 tablespoons of olive oil to the high olive oil diet the authors created the equivalent of a straw man that was easy knock over. Even if their conclusions were correct, nobody has recommended the addition of 4 tablespoons of olive oil to any diet as a heart-healthy approach.

Mediterraneans don’t add 4 tablespoons of olive oil to their diet. Olive oil is part of the foods they eat and the way they prepare their food.

Why The Headlines Are Misleading: Of course, the headlines were misleading because they ignored the many flaws of the study.

However, I find it amusing that some of the headlines came from “Forks Over Knives” an organization that advocates for a very low-fat plant-based diet. They were using this study to question the value of olive oil as part of a whole-food plant-based diet.

However, when you look at the study, 32% of calories came from fat in the low olive oil diet, and 49% of calories came from fat in the high olive oil diet.

For perspective:

The low-fat whole-food plant-based diet recommended by “Forks Over Knives” has <10-15% of calories from fat.

The Mediterranean diet typically contains 35-40% of calories from fat.

- Around 18-19% of that is monounsaturated fat.

- Around 8% of that is saturated fat.

The typical American diet also contains 35-40% of calories from fat.

- Around 12-14% of that is monounsaturated fat.

- Around 12% of that is saturated fat.

In other words, the low olive oil diet in this study resembles the fat content of the Mediterranean and typical American diets, not the low-fat whole food plant-based diet recommended by “Forks Over Knives”.

And the high olive oil diet contains fat levels not seen in any natural diet. Except for a few keto enthusiasts, I don’t know of any experts who think getting almost 50% of your calories from any kind of fat is a good thing.

What Is The Truth About Olive Oil And You?

As described above, the study behind the headlines is a very small, very short study with multiple flaws. So, you can ignore headlines like “Olive oil is overrated” or “Olive oil doesn’t deserve its health halo.”

The second study I discussed is much larger (92,383 participants) and of much longer duration (28 years). More importantly, it measures health outcomes, not blood biomarkers that might predict health outcomes.

Finally, the second study was not measuring the health benefits of the Mediterranean diet, as many other studies have done. It was looking at the effect of varying olive oil intakes in the American diet. The high olive oil intakes in this study were less than those seen in the Mediterranean diet. This is good news for the average American who may feel overwhelmed trying to adopt to a Mediterranean diet.

This study reinforces previous studies showing that olive oil is healthy. But let me put this into context.

Olive oil is not a superfood. This study showed that it is no healthier than other plant oils. It is, however, considered one of the best vegetable oils for sauteing. It is also less susceptible to oxidation than seed oils, although I still recommend you store it in the refrigerator.

It is not something you add to your diet. It is something you incorporate into your diet. People who live in Mediterranean regions:

- Cook with olive oil.

- Use olive oil in their salad dressings and drizzle a little olive oil on cooked vegetable and pasta dishes instead of adding butter.

- Dip their bread in olive oil rather than using butter or mayonnaise.

- Use it in spreads like tapenade or hummus.

- Use olives in cooking.

Finally, look for extra virgin olive oil. That doesn’t mean you need to spend “an arm and a leg”. But I would do a little online research before I bought the cheapest brand at the discount store.

The Bottom Line

You may have seen recent headlines claiming that olive oil is overrated and that it doesn’t deserve its “health halo”. So, I looked at the study behind the headlines.

It was a very small, very short study with multiple flaws. You can forget the headlines.

For context I also reviewed another recent study. It was a much larger (92,383 participants) and longer duration (28 years) study. More importantly, it measured actual health outcomes, not just blood biomarkers that might predict health outcomes.

It concluded that olive oil is good for us. It is healthier than most fats commonly found in the American diet, but it is no healthier than other plant oils.

For more details on these studies, what they mean for you, and how to incorporate more olive oil into your diet read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

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About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years.

Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”.

Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 45 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

Can Healthy Eating Help You Lose Weight?

September 27, 2022 by Dr. Steve Chaney

Who Benefits Most From A Healthy Diet?

Author: Dr. Stephen Chaney

Fad diets abound. High protein, low carb, low fat, vegan, keto, paleo – the list is endless. They all claim to be backed by scientific studies showing that you lose weight, lower your cholesterol and triglycerides, lower your blood pressure, and smooth out your blood sugar swings.

They all claim to be the best. But any reasonable person knows they can’t all be the best. Someone must be lying.

My take on this is that fad diet proponents are relying on “smoke and mirrors” to make their diet look like the best. I have written about this before, but here is a brief synopsis:

They compare their diet with the typical American diet.

- Anything looks good compared to the typical American diet.

- Instead, they should be comparing their diet with other weight loss diets. That is the only way we can learn which diet is best.

They are all restrictive diets.

- Any restrictive diet will cause you to eat fewer calories and to lose weight.

- As little as 5% weight loss results in lower cholesterol & triglycerides, lower blood pressure, and better control of blood sugar levels.

Simply put, any restrictive diet will give you short-term weight loss and improvement in blood parameters linked to heart disease, stroke, and diabetes. But are these diets healthy long term? For some of them, the answer is a clear no. Others are unlikely to be healthy but have not been studied long term. So, we don’t know whether they are healthy or not.

What if you started from the opposite perspective? Instead of asking, “Is a diet that helps you lose weight healthy long term?”, what if you asked, “Can healthy eating help you lose weight?” The study (S Schutte et al, American Journal of Clinical Nutrition, 115: 1-18, 2022) I will review this week asked that question.

More importantly, it was an excellent study. It compared a healthy diet to an unhealthy diet with exactly the same degree of caloric restriction. And it compared both diets to the habitual diet of people in that area. This study was performed in the Netherlands, so both weight loss diets were compared to the habitual Dutch diet.

How Was The Study Done?

This was a randomized controlled trial, the gold standard of clinical studies. The investigators recruited 100 healthy, abdominally obese men and women aged 40-70. At the time of entry into the study none of the participants:

Had diabetes.
Smoked
Had a diagnosed medical condition.
Were on a medication that interfered with blood sugar control.
Were on a vegetarian diet.

The participants were randomly assigned to:

A high-nutrient quality diet that restricted calories by 25%.
A low-nutrient-quality diet that restricted calories by 25%.
Continue with their habitual diet.

The study lasted 12 weeks. The participants met with a dietitian on a weekly basis. The dietitian gave them the foods for the next week and monitored their adherence to their assigned diet. They were advised not to change their exercise regimen during the study.

At the beginning and end of the study the participants were weighed, and cholesterol, triglycerides, and blood pressure were measured.

Can Healthy Eating Help You Lose Weight?

To put this study into context, these were not healthy and unhealthy diets in the traditional sense.

Both were whole food diets.
Both included fruits, vegetables, low-fat dairy, and lean meats.
Both restricted calories by 25%.

The diets were designed so that the “high-nutrient quality” diet had significantly more plant protein (in the form of soy protein), fiber, healthy fats (monounsaturated and omega-3 fats), and significantly less fructose and other simple sugars than the “low-nutrient-quality” diet.

At the end of 12 weeks:

Participants lost significant weight on both calorie-restricted diets compared to the group that continued to eat their habitual diet.

- That is not surprising. Any diet that successfully restricts calories will result in weight loss.

Participants on the high-nutrient quality diet lost 33% more weight than participants on the low-nutrient-quality diet (18.5 pounds compared to 13.9 pounds).

Participants on the high-nutrient quality diet lost 50% more inches in waist circumference than participants on the low-nutrient-quality diet (1.8 inches compared to 1.2 inches).

- This is a direct measure of abdominal obesity.

When the investigators measured blood pressure, fasting total cholesterol levels, and triglyceride levels:

These cardiovascular risk factors were significantly improved on both diets.

- Again, this would be expected. Any diet that causes weight loss results in an improvement in these parameters.

The reduction in total serum cholesterol was 2.5-fold greater and the reduction in triglycerides was 2-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.

The reduction in systolic blood pressure was 2-fold greater and the reduction in diastolic blood pressure was 1.67-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.

The authors concluded, “Our results demonstrate that the nutrient composition of an energy-restricted diet is of great importance for improvements of metabolic health in an overweight, middle-aged population. A high-nutrient quality energy-restricted diet enriched with soy protein, fiber, monounsaturated fats, omega-3 fats, and reduced in fructose provided additional health benefits over a low-nutrient quality energy-restricted diet, resulting in greater weight loss…and promoting an antiatherogenic blood lipid profile.”

In short, participants in this study lost more weight and had a better improvement in risk factors for heart disease on a high-nutrient-quality diet than on a low-nutrient-quality diet. Put another way, healthy eating helped them lose weight and improved their health.

Who Benefits Most From A Healthy Diet?

None of the participants in this study had been diagnosed with diabetes when the study began. However, all of them were middle-aged, overweight, and had abdominal obesity. That means many of them likely had some degree of insulin resistance.

Because of some complex metabolic studies that I did not describe, the investigators suspected that insulin resistance might influence the relative effectiveness of the two energy-restricted diets.

To test this hypothesis, they used an assay called HOMA-IR (homeostatic model assessment of insulin resistance). Simply put, this assay measures how much insulin is required to keep your blood sugar under control.

They used a HOMA-IR score of 2.5 to categorize insulin resistance among the participants.

Participants with a HOMA-IR score >2.5 were categorized as insulin-resistant. This was 55% of the participants.

Participants with a HOMA-IR score ≤2.5 were categorized as insulin-sensitive. This was 45% of the participants.

When they used this method to categorize participants they found:

Insulin-resistant individual lost about the same amount of weight on both diets.

Insulin-sensitive individuals lost 66% more weight on the high-nutrient-quality diet than the low-nutrient-quality diet (21.6 pounds compared to 13.0 pounds).

The investigators concluded, “Overweight, insulin-sensitive subjects may benefit more from a high- than a low-nutrient-quality energy-restricted diet with respect to weight loss…”

What Does This Study Mean For You?

Simply put this study confirms that:

Caloric restriction leads to weight loss, and…

Weight loss leads to improvement in cardiovascular risk factors like total cholesterol, triglycerides, and blood pressure.

- This is not new.

- This is true for any diet that results in caloric restriction.

This study breaks new ground in that a high-nutrient quality diet results in significantly better:

Weight loss and…

Reduction in cardiovascular risk factors…

…than a low-nutrient quality diet. As I said above, the distinction between a “high-nutrient-quality” diet and a “low-nutrient-quality” diet may not be what you might have expected.

Both diets were whole food diets. Neither diet allowed sodas, sweets, and highly processed foods.

Both included fruits, vegetables, grains, and lean meats.
Both reduced caloric intake by 25%.

- If you want to get the most out of your weight loss diet, this is a good place to start.

In this study the investigators designed their “high-nutrient-quality” diet so that it contained:

More plant protein in the form of soy protein.

- In this study they did not reduce the amount of animal protein in the “high-nutrient-quality” diet. They simply added soy protein foods to the diet. I would recommend substituting soy protein for some of the animal protein in the diet.

More fiber.

- The additional fiber came from substituting whole grain breads and brown rice for refined grain breads and white rice, adding soy protein foods, and adding an additional serving of fruit.

More healthy fats (monounsaturated and omega-3 fats).

- The additional omega-3s came from adding a fish oil capsule providing 700mg of EPA and DHA.

Less simple sugars. While this study focused on fructose, their high-nutrient-quality diet was lower in all simple sugars.

All these changes make great sense if you are trying to lose weight. I would distill them into these 7 recommendations.

Follow a whole food diet. Avoid sodas, sweets, and highly processed foods.

Include all 5 food groups in your weight loss diet. Fruits, vegetables, whole grains, dairy, and lean proteins all play an important role in your long-term health.

Eat a primarily plant-based diet. My recommendation is to substitute plant proteins for at least half of your high-fat animal proteins. And this study reminds us that soy protein foods are a convenient and effective way to achieve this goal.

Eat a diet high in natural fibers. Including fruits, vegetables, whole grains, beans, nuts, seeds, and soy foods in your diet is the best way to achieve this goal.

Substitute healthy fats (monounsaturated and omega-3 fats) for unhealthy fats (saturated and trans fats) in your diet. And this study reminds us that it is hard to get enough omega-3s in your diet without an omega-3 supplement.

Reduce the amount of added sugar, especially fructose, from your diet. That is best achieved by eliminating sodas, sweets, and highly processed foods from the diet. I should add that fructose in fruits and some healthy foods is not a problem. For more information on that topic, I refer you to a previous “Health Tips” article .

Finally, I would like to remind you of the obvious. No diet, no matter how healthy, will help you lose weight unless you cut back on calories. Fad diets achieve that by restricting the foods you can eat. In the case of a healthy diet, the best way to do it is to cut back on portion sizes and choose foods with low caloric density.

I should touch briefly on the third major conclusion of this study, namely that the “high-nutrient quality diet” was not more effective than the “low-nutrient-quality” diet for people who were insulin resistant. In one sense, this was not news. Previous studies have suggested that insulin-resistant individuals have more difficulty losing weight. That’s the bad news.

However, there was a silver lining to this finding as well:

Only around half of the overweight, abdominally obese adults in this study were highly insulin resistant.

- That means there is a ~50% chance that you will lose more weight on a healthy diet.

Because both diets restricted calories by 25%, insulin-resistant individuals lost weight on both diets.

- That means you can lose weight on any diet that successfully reduces your caloric intake. That’s the good news.

- However, my recommendation would still be to choose a high-nutrient quality diet that is designed to reduce caloric intake, because that diet is more likely to be healthy long term.

The Bottom Line

A recent study asked, “Can healthy eating help you lose weight?” This study was a randomized controlled study, the gold standard of clinical studies. The participants were randomly assigned to:

A high-nutrient quality diet that restricted calories by 25%.
A low-nutrient-quality diet that restricted calories by 25%.
Continue with their habitual diet.

These were not healthy and unhealthy diets in the traditional sense.

Both were whole food diets.
Both included fruits, vegetables, low-fat dairy, and lean meats.
Both restricted calories by 25%.

At the end of 12 weeks:

Participants on the high-nutrient quality diet lost 33% more weight than participants on the low-nutrient-quality diet (18.5 pounds compared to 13.9 pounds).

When the investigators measured cardiovascular risk factors at the end of 12 weeks:

The reduction in total serum cholesterol was 2.5-fold greater and the reduction in triglycerides was 2-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.

The reduction in systolic blood pressure was 2-fold greater and the reduction in diastolic blood pressure was 1.67-fold greater in the high-nutrient quality diet group than in the low-nutrient-quality diet group.

For more details on this study, what this study means for you, and my 7 recommendations for a healthy weight loss diet, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Does Olive Oil Help You Live Longer?

March 8, 2022 by Dr. Steve Chaney

Which Fat Is Healthiest?

Author: Dr. Stephen Chaney

If you believe the headlines, olive oil is a superfood. It is often described as the star of the Mediterranean diet. It is referred to as the healthiest of dietary fats. Is this true, or is it hype?

Olive oil’s resume is impressive:

It is rich in monounsaturated fatty acids, which…

- Are less susceptible to oxidation than polyunsaturated oils.

- Make our arteries more flexible, which lowers blood pressure.

- Lower LDL-cholesterol levels, which reduces the risk of heart disease.

Extra-virgin olive oil contains phytonutrients and tocopherols (various forms of vitamin E), which…

- Have anti-inflammatory properties.

- Improve insulin sensitivity and blood sugar control.

Olive oil consumption is also associated with healthier gut bacteria, but it is not clear whether this is due to olive oil or to the fact that a Mediterranean diet is also richer in fresh fruits, vegetables, and whole grains.

Several recent studies have shown that olive oil consumption is associated with a lower risk of heart disease. However, these studies were conducted in Mediterranean countries where the average intake of olive oil (3 tablespoons/day) is much greater than in the United States (0.3 tablespoons/day).

The current study (M Guasch-Ferré et al, Journal of the American College of Cardiology, 79: 101-112, 2022) was designed to test whether:

The amount of olive oil Americans consume decreases the risk of heart disease.

Whether olive oil consumption had benefits beyond a reduction in heart disease risk.

How Was This Study Done?

This study combined data from 60,582 women enrolled in the Nurses’ Health Study and 31,801 men enrolled in the Health Professionals Follow-Up Study). The participants:

Were free of heart disease and diabetes at the start of the study.

Were 56 at the start of the study with an average BMI of 25.6 (Individuals with BMIs in the 25-30 range are considered overweight, so they were at the lowest end of the overweight range).

The Nurses’ Health Study and Health Professional Follow-Up Study are both association studies, meaning they looked at the association between olive oil consumption and health outcomes. They cannot directly prove cause and effect. However, they are very strong association studies because:

Every 2 years, participants filled out a questionnaire that updated information on their body weight, smoking status, physical activity, medications, multivitamin use, and physician-diagnosed diseases.

Every 4 years, participants filled out a comprehensive food frequency questionnaire.

In other words, this study did not just rely on the participant’s lifestyle, dietary intake, and health at the beginning of the study, as so many association studies do. It tracked how each of these variables changed over time.

The participants were followed for an average of 28 years and their average olive oil intake over those 28 years was correlated with all-cause mortality and mortality due to specific diseases.

Deaths were identified from state vital statistics, the National Death index, reports by next of kin, or reports by postal authorities.

Causes of death were determined by physician review of medical records, medical reports, autopsy reports, or death certificates.

Does Olive Oil Help You Live Longer?

During the 28 years of this study:

Olive oil consumption in the United States increased from an average of ~1/3 teaspoon/day to ~1/3 tablespoon/day.

Margarine consumption decreased from 12 g/day to ~4 g/day.

The consumption of all other fats and oils remained about the same.

As I mentioned above, olive oil consumption was averaged over the life of the study for each individual. When the investigators compared people consuming the highest amount of olive oil (>0.5 tablespoon/day) with people consuming the least olive oil (0 to 1 teaspoon/day):

Mortality from all causes was decreased by 35% for the group consuming the most olive oil.

However, the group consuming the most olive oil also was more physically active, had a healthier diet, and consumed more fruits and vegetables than the group who consumed the least olive oil.

After correcting for all those factors, mortality from all causes was decreased by 19% for the group consuming the most olive oil.

The authors concluded, “We found that greater consumption of olive oil was associated with lower risk of total…mortality… Our results support current dietary recommendations to increase the intake of olive oil…to improve overall health and longevity.” (I will fill in the blanks in this statement once I have covered other aspects of this study)

The authors also said, “Of note, our study showed that benefits of olive oil can be observed even when consumed in lower amounts than in Mediterranean countries.”

Are There Other Benefits From Olive Oil Consumption?

The study didn’t stop there. The investigators also looked at the effect of olive oil consumption on the major killer diseases in the United States and other developed countries. When they compared the effect of olive oil consumption on cause-specific mortality, they found that the group who consumed the most olive oil reduced their risk of dying from:

Cardiovascular disease by 19%.

Cancer by 17%

Respiratory disease by 18%.

Neurodegenerative disease (cognitive decline and Alzheimer’s disease) by 29%.

- The reduction in neurodegenerative disease was much greater for women (34% decrease) than for men (19% decrease).

With this information I can fill in one of the blanks in the author’s conclusions: “We found that greater consumption of olive oil was associated with lower risk of total and cause-specific mortality… Our results support current dietary recommendations to increase the intake of olive oil…to improve overall health and longevity.”

Which Fats Are Healthiest?

The sample size was large enough and the dietary information complete enough for the investigators to also estimate the effect of substituting olive oil for other dietary fats and oils.

They found that every ¾ tablespoon of olive oil substituted for an equivalent amount of:

Margarine decreased total mortality by 13%.

Butter decreased total mortality by 14%.

Mayonnaise deceased total mortality by 19%

Dairy fat decreased total mortality by 13%.

- The same beneficial effects of substituting olive oil for other fats were seen for cause-specific mortality (cardiovascular disease, cancer, respiratory disease, and neurodegenerative disease).

- There was a linear dose-response. This means that substituting twice as much olive oil for other dietary fats doubled the beneficial effects on total and cause-specific mortality.

However, substituting olive oil for polyunsaturated vegetable oils had no effect on total and cause-specific mortality.

Now I can fill in the remaining blanks in the author’s conclusion: “We found that greater consumption of olive oil was associated with lower risk of total and cause-specific mortality. Replacing other types of fat, such as margarine, butter, mayonnaise, and dairy fat, with olive oil was also associated with a lower risk of mortality. Our results support current dietary recommendations to increase the intake of olive oil and other unsaturated vegetable oils in place of other fats to improve overall health and longevity.”

What Does This Study Mean For Us?

As I said above, this is an association study, and association studies do not prove cause and effect. However:

1) This is a very strong association study because:

- It is a very large study (92,383 participants).

- It followed the participants over a long time (28 years).

- It utilized a very precise dietary analysis.

- Most importantly, it tracked the participant’s lifestyle, dietary intake, and health at regular intervals throughout the study. Most association studies only measure these variables at the beginning of the study. They have no idea how they change over time.

2) This study is consistent with several previous studies showing that olive oil consumption decreases the risk of dying from heart disease.

3) This study draws on its large population size and precise dietary analysis to strengthen and extend the previous studies. For example:

- The study showed that increased olive oil consumption also reduced total mortality and mortality due to cancer, respiratory disease, and neurodegenerative disease.

- The study measured the effect of substituting olive oil for other common dietary fats.

- The study showed that increased olive oil consumption in the context of the American diet was beneficial.

I should point out that the headlines you have seen about this study may be misleading.

While the headlines may have depicted olive oil as a superfood, this study did not find evidence that olive oil was more beneficial than other unsaturated vegetable oils. Again, this is consistent with many previous studies showing that substituting vegetable oils for other dietary fats reduces the risk of multiple diseases.

The headlines focused on the benefits of increasing olive oil consumption. However, they neglected the data showing that increasing olive oil (and other vegetable oils) was even more beneficial (35% reduction in total mortality) in the context of a healthy diet – one with increased intake of fruits, vegetables, whole grains, nuts, legumes, and long-chain omega-3s and decreased intake of red & processed meats, sodium, and trans fats.

So, my recommendation is to follow a whole food, primarily plant-based diet and substitute extra-virgin olive oil and cold pressed vegetable oils for some of the animal fats in your diet.

Some vegan enthusiasts recommend a very low-fat whole food plant-based diet. They point to studies showing that such diets can actually reverse atherosclerosis. However:

Those studies are very small.

The overall diet used in those studies is a very healthy plant-based diet.

The studies did not include a control group following the same diet with olive oil or other vegetable oils added to it, so there is no comparison of a healthy vegan diet with and without vegetable oils.

If you have read my book, “Slaying the Food Myths”, you know that my recommendations encompass a variety of whole food, primarily plant-based diets ranging all the way from very-low fat vegan diets to Mediterranean and DASH diets. Choose the one that best fits your food preferences and the one you will be most able to stick with long term. You will be healthier, and you may live longer.

The Bottom Line

A recent study looked at the effect of olive oil consumption on the risk dying from all causes and from heart disease, cancer, respiratory disease, and neurodegenerative diseases. When the study compared people consuming the highest amount of olive oil (>0.5 tablespoon/day) with people consuming the least olive oil (0 to 1 teaspoon/day):

Mortality from all causes was decreased by 19% for the group consuming the most olive oil.

They also found that the group who consumed the most olive oil reduced their risk of dying from:

Cardiovascular disease by 19%.

Cancer by 17%

Respiratory disease by 18%.

Neurodegenerative disease (cognitive decline and Alzheimer’s disease) by 29%.

They also found that every ¾ tablespoon of olive oil substituted for an equivalent amount of:

Margarine decreased total mortality by 13%.

Butter decreased total mortality by 14%.

Mayonnaise deceased total mortality by 19%

Dairy fat decreased total mortality by 13%.

However, substituting olive oil for polyunsaturated vegetable oils had no effect on total and cause-specific mortality.

The authors concluded, “We found that greater consumption of olive oil was associated with lower risk of total and cause-specific mortality. Replacing other types of fat, such as margarine, butter, mayonnaise, and dairy fat, with olive oil was also associated with a lower risk of mortality. Our results support current dietary recommendations to increase the intake of olive oil and other unsaturated vegetable oils in place of other fats to improve overall health and longevity.”

For more details and a summary of what this study means for you, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.