Therapeutic Olive Oil: New Research on Food as Medicine

Olive oil contains a fat molecule that protects against diseases involving iron, suggesting new food-based treatment options

Brent R. Stockwell, Ph.D.
Wise & Well


Child looks at olive oil bottles
Image credit: Brent Stockwell

A baby girl died in 1992 when her two-year-old sibling fed her more than 30 glossy red and green tablets. Inside the medicine was the metal iron, deadly when taken in excess. The tablets were intended as a supplement for their mother, but found their way into the children’s hands and mouths. Thousands of children are poisoned with iron through such accidents each year, causing tragic deaths.

Iron can cause severe damage, but is also essential for health — too much or too little iron impairs health. Eating foods that provide sufficient iron but also protect against iron toxicity may be key to preventing iron poisoning, and broadly promoting health and longevity. The longest-lived humans have less iron in their blood, as detected by a technology called mass spectrometry, which involves precisely measuring the abundance of different metals based on their exact mass.

“Food is an important part of a balanced diet, “ said Fran Lebowitz.

Indeed, different foods profoundly alter health. My colleagues and I have been studying how iron causes damage and how some fat molecules protect against iron injury. Olive oil and macadamia nuts are protective foods, our new study shows, but a fat-control gene is key for unlocking the protective effect of these fatty molecules. Our data reveal a new axis through which diet controls health and that the details matter — the right foods balance each other.

Iron can be fatal

Iron is the Goldilocks metal — too little iron causes weakness and tiredness, due to insufficient oxygen delivery to the body, but too much iron causes damage to the stomach and related parts of the body, and even death. Iron damage can occur through inheritance, being passed from parent to child, as in the disease hemochromatosis. This disease, so named because it was thought that the unusual color (-chroma-) in these patients was caused by their blood (hemo-), causing this specific condition (-tosis).

Patients in the intensive care unit of hospitals because of trauma, surgery, or severe infection often have multi-organ failure due to elevated blood levels of iron. The source of increased iron in these critical care patients is not known, but may derive from parts of the body that release iron stores when damaged. Reducing the negative effects of iron in such diseases is a challenge.

There are two existing treatments for iron poisoning — bleeding and chelation. Removing iron by bleeding can help with mild iron overload, as blood is the major reservoir of iron. Patients with sickle cell disease have impaired blood function, and often receive blood transfusions to repair the functioning of their blood. However, the additional iron-rich blood these patients receive, while helpful for correcting sickle cell symptoms, can also cause iron overload. Many of these patients take drugs that can chelate, or attach to, iron and eliminate it from the body; such treatments can cause allergic reactions, eye damage, hearing loss, bone thinning, and stomach problems, as iron is important for normal health. Better ways of treating iron overload are needed.

An olive oil fat protects against iron

Olive oil has a component that can block the toxic effects of iron, as we discovered in our newly reported research, done in collaboration with Marcelo Farina, PhD, at Universidade Federal de Santa Catarina in Brazil, and Antonio Miranda Vizuete, PhD, at Instituto de Biomedicina de Sevilla in Spain. The results were just published in the scientific journal Cell Chemical Biology.

Iron’s essential role and dangerous effects come from its ability to act as a small electrical wire. When humans and animals digest nutrients, they use iron’s role as a wire as part of the process of converting sugar, fat, and protein in food into energy.

But iron has a dark side: It also can short-circuit and damage other parts of the body.

The harmful effects of iron can be prevented by an abundant ingredient in olive oil called oleic acid, our study found. The name oleic acid comes from the Latin oleum, a term for oil, as oleic acid is the most common molecule in olive oil. The acid part of this chemical name refers to the fact that it is acidic, like vinegar and tart fruits. Oleic acid is associated with health and longevity, such as being part of the Mediterranean diet, which involves eating fish, whole grains, and olive oil, along with fruit, nuts and vegetables, all favored over red meat. Olive oil is one of the best sources of oleic acid.

Another great source of oleic acid is oil from macadamia nuts, which are also associated with good health. A recent clinical trial by other researchers showed that macadamia nuts improve heart health.

We found in our research that worms, mice and even human cells given iron suffered severe damage. However, oleic acid prevented this damage. Iron attacked certain fat molecules that are particularly susceptible to injury. Oleic acid was resistant to iron’s effects and was able to substitute for the delicate fats, preventing iron’s toxic effect. While studies on cells, mice, and worms don’t always translate directly into human benefit, we think that given the known benefits of olive oil, it is possible that this oil might be useful for treating iron overload in people.

In addition, iron is involved in driving many diseases, even when it doesn’t accumulate to excess. Common brain, heart, liver, and kidney diseases have been reported to involve toxic effects of iron. These reports suggest that oleic acid might be broadly beneficial on many diseases, not just cases of iron poisoning and iron overload. While this is more speculative, it will likely be a subject of research in the near term.

A gene that determines whether olive oil works

But wait — it is not so easy! We also discovered a key gene that determines whether oleic acid can be protective. Genes compose the instruction manual of people and animals that dictate many aspects of health and disease. We found that one particular gene that controls fat production is critical for the ability of oleic acid to protect against injury. When this gene, named PPARA, was not active, oleic acid was not helpful, as oleic acid couldn’t replace delicate fats without the help of PPARA.

These results show that the right diet could help people with iron poisoning or iron overload. People who consume too much iron may benefit from consumption of olive oil. A Mediterranean diet or just a diet rich in olive oil could blunt the toxic effects of iron. Macadamia nuts would also likely work. While olive oil has other benefits for the broader population, olive oil would particularly benefit these individuals through protection against iron.

However, the beneficial effects of oleic acid do depend on the PPARA gene, so it could be helpful for physicians to check if this gene is active in people who are considering taking olive oil or macadamia nut oil to protect against iron. That would require a new medical test for the activity of the PPARA gene, which is not hard to do, but doesn’t yet exist.

“Iron, at the same time [is] the most useful and the most fatal instrument in the hand of mankind,” as Pliny the Elder said more than 2,000 years ago. Little did he know that the same concept applies to iron and our health. Now we know that iron’s ferocious power can be tamed by oleic acid. Yes, as Fran Lebowitz said, food is important, and balancing the right ingredients is the ticket to health and longevity.



Brent R. Stockwell, Ph.D.
Wise & Well

Chair and Professor of Biological Sciences at Columbia University. Top Medium writer in Science, Creativity, Health, and Ideas