What 28 Years of Data Tells Us About Olive Oil and Longevity

In the early 1990s, researchers began asking a simple question on a food questionnaire: How often do you use olive oil?What followed was a decades-long exploration of how a single kitchen staple might influence life and death.

A Unique Window Into Long-Term Health

The study pulled from two of the most respected long-term health cohorts in the U.S.—the Nurses’ Health Study, which began in 1976 with over 120,000 women, and the Health Professionals Follow-up Study, which started in 1986 and tracked over 50,000 men.

By 1990, both studies added detailed questions about diet, including olive oil use, to their regular follow-up surveys. Anyone who already had cancer or heart disease at that time was excluded to give a clean slate for tracking health outcomes moving forward.

In total, over 92,000 participants made the cut for analysis, and they were followed for up to 28 years.

Measuring Diet in the Real World

Every four years, participants were asked to complete detailed dietary questionnaires—covering more than 130 food items. Among them were three key questions about olive oil:

• Did they use it in salad dressings?

• Did they drizzle it over bread or food?

• Did they cook with it at home?

From these responses, the researchers estimated daily intake. One tablespoon was assumed to be about 13.5 grams of olive oil.

They didn’t stop at olive oil—they tracked consumption of butter, margarine, mayonnaise, and dairy fat too. This allowed them to compare not just how much olive oil people ate, but what it might be replacing.

What Happened Over 28 Years

Over the course of the study, nearly 37,000 people died. The researchers meticulously tracked the cause of each death—whether from cardiovascular disease, cancer, neurodegenerative conditions, respiratory illness, or other causes—using medical records and death certificates.

As they followed the participants, the researchers noticed a shift: olive oil consumption rose steadily, from about 1.6 grams per day in 1990 to over 4 grams per day by 2010.

And that increase mattered.

People who consumed the most olive oil had significantly lower risks of dying—from any cause, and also from specific causes like heart disease, cancer, and neurodegenerative diseases.

The Power of Replacing, Not Just Adding

The most striking finding wasn’t just that olive oil was associated with better health—it was what happened when people replaced other fats with it.

Swapping just 10 grams per day of margarine, butter, mayonnaise, or dairy fat with olive oil led to meaningfully lower risks of death.

This isn’t about adding more fat to your diet - it’s about choosing the right kind.

The Science Behind the Stats

Of course, this kind of long-term study needs to account for hundreds of variables. The researchers used complex statistical models to adjust for everything from age, smoking habits, and physical activity to family history, medication use, and overall diet quality.

They even performed rigorous “sensitivity analyses” - tweaking assumptions to make sure the findings held up across different scenarios, such as accounting for socioeconomic status or tracking changes in diet over time.

And they did. The association between higher olive oil intake and lower mortality remained strong.

What This Means for You

This isn’t a clinical trial—it can’t prove cause and effect. And the study population was mostly non-Hispanic white, so results may not apply universally. Still, the sheer size, length, and depth of the data make the findings hard to ignore.

If there’s one practical takeaway: ditch the butter or margarine, and reach for olive oil instead.

This study reinforces what Mediterranean cultures have known for centuries—olive oil isn’t just a flavor enhancer. It’s a life extender.