Media Release

More Evidence the Mediterranean Diet is Good for You

Research Led by Dr. David Jenkins of St. Michael’s Hospital Finds Benefits to Adding Monounsaturated Fat to a Diet Proven to Lower Bad Cholesterol

Toronto, November 1, 2010

There’s more evidence that the Mediterranean diet helps promote good cholesterol.

Monounsaturated fats, found in such foods as nuts, avocados and olive oil, are already known to raise HDL (“healthy”) cholesterol levels.

Now, researchers at St. Michael’s Hospital studying how to combine cholesterol-lowering foods (known as a “diet portfolio”) to maximize their impact have added monounsaturated fats to a vegetarian diet previously shown to lower LDL (“bad”) cholesterol by 28 per cent.

They found the combination lowered bad cholesterol even more -- by 35 per cent – while also raising good cholesterol by 12.5 per cent. The most benefit came when the monounsaturated fats replaced carbohydrates in the diet.

Their study will be published in the Canadian Medical Association Journal on Monday.

“Our concern was that trying to raise HDL cholesterol with monounsaturated fats might have reduced the effectiveness of our cholesterol-lowering dietary portfolio,” said Dr. David Jenkins, the lead author of the study and director of the hospital’s Risk Factor Modification Centre.

“The fact that this was not the case has opened the way to a dietary approach with a potentially much stronger ability to reduce cardiovascular risk.”

Low levels of HDL cholesterol and high levels of LDL cholesterol are risk factors for cardiovascular disease. Consuming monounsaturated fats, common on the Mediterranean diet, is a current approach to raising good cholesterol levels.

In Jenkins’ study, 24 patients with mild to moderately high levels of cholesterol ate a diet low in saturated fats (such as those found in meat and dairy products) for one month. For the next month, they ate a vegetarian diet that included oats, barley, psyllium, eggplant, okra, soy, almonds and a margarine enriched with plant sterols. Previous research has shown this diet lowers LDL cholesterol by approximately 30 per cent, about the same as the drug lovastatin, sold as Mevacor.

For half the group, researchers substituted 13 per cent of the calories from carbohydrates with a sunflower oil high in monounsaturated fat. Participants could replace some of the sunflower oil with avocado oil.

Researchers found a significant increase in HDL cholesterol in that group over the two-month, along with the substantial reduction in LDL cholesterol. HDL levels did not change in the other group.

“The addition of monounsaturated fats increased HDL cholesterol and therefore may further enhance the cardioprotective effect of the cholesterol-lowering dietary portfolio without diminishing its cholesterol-lowering effect,” Dr. Jenkins said.

About St. Michael’s

St. Michael’s Hospital provides compassionate care to all who walk through its doors. The Hospital also provides outstanding medical education to future health care professionals in more than 23 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, and care of the homeless are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing Knowledge Institute, research at St. Michael’s Hospital is recognized and put into practice around the world. Founded in 1892, the Hospital is fully affiliated with the University of Toronto.

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