The Oily Truth

Has the final mystery of the Mediterranean diet been solved?

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Just what makes the Mediterranean diet so healthy has been a matter of debate for years. The diet is recognized for significantly reducing the risk for stroke and heart disease, certain cancers, and dementias such as Alzheimer’s disease. Although not a uniform diet, it typically features an abundance of grains, fruits, and vegetables, and also fish and moderate amounts of wine. And don’t forget olive oil, an ingredient often overlooked when the diet is translated in butter-loving American kitchens. In true Mediterranean diets, olive oil is the main fat, and there is lots of it. “Olive oil is the central pillar of the diet, a major source of calories in what is overall a low calorie diet,” says Paul Breslin, sensory scientist at the Monell Chemical Senses Center in Philadelphia.

Breslin and his colleague Gary Beauchamp, are involved in work that just might end the healthy diet debate. Their work has revealed that olive oil — which was already well-regarded for being monounsaturated and high in anti-oxidants — has remarkable anti-inflammatory effects as well.

The two started studying olive oil after Beauchamp attended a tasting in Sicily and discovered that it caused an unusual irritation at the back of his throat. This was noteworthy because it reminded him of the characteristic sting of ibuprofen, an irritant that also only affects the pharynx in the back of the throat — and a compound that, serendipitously, he already studied in his lab. Most irritants like peppers, mustards, gingers, and strong alcohols are different in that they affect the whole mouth with their burn or sting.

Breslin and Beauchamp began to search for a connection between the sensory and pharmacological properties of ibuprofen and olive oil. They found it in a naturally-occurring chemical in olive oil that inhibits the activity of cyclooxygenase (COX) enzymes, and they named it oleocanthal: oleo=olive, canth=sting, and al=aldehyde. COX inhibition is also the key action of ibuprofen and some other painkillers that confers their anti-inflammatory effect. The COX-blocking activity in three tablespoons of olive oil equals about 10 percent of the ibuprofen dose recommended for pain relief in adults.

Today, as medical research increasingly reveals inflammation as the cause of chronic diseases, the discovery of oleocanthal sheds additional light on how olive oil improves health and reduces risk. Just any old olive oil, however, will not do the trick. Fresh, cold-pressed extra-virgin or virgin olive oils contain much more oleocanthal than refined — so-called “light” — olive oils from later pressings. In fact, the irritating intensity of an olive oil — how much it stings the throat and induces coughing — is directly related to how much oleocanthal it contains.

Researchers at various institutions are currently investigating the direct impact of olive oil consumption on cancer and other diseases, while the Monell researchers are now doing physiology and biological studies to better learn how olive oil works its magic.

In the meantime, Breslin and Beauchamp have taken to using premium olive oil in their home kitchens, drizzled liberally on salads, pizzas, pastas, and sandwiches. Inspired, I went out and spent $26 on a small bottle of extra virgin olive oil from an Italian specialty store. It felt like too much, but if the science is to be trusted, this is one case where spending extra for the best is worth it. • 12 February 2008

SOURCE: “Ibuprofen-like activity in extra-virgin olive oil.” Beauchamp GK, Keast RSJ, Morel D, et al. Nature, 2005;437:45-6. The Effect of Polyphenols in Olive Oil on Heart Disease Risk Factors: A Randomized Trial.” Covas M-I, Nyyssönen K, Poulsen HE, et al. Ann Intern Med, 2006;145:333-341. “Olive oil and longevity.” Trichopoulou A & Dilis V. Mol Nutr Food Res. 2007;51:1275-8.

 

Jennifer Fisher Wilson is the science reporter for Annals of Internal Medicine. Her stories are available at www.annals.org.

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