A recent study found that a Mediterranean diet lowered the risk of heart attack and stroke.iStockPhoto

A rigorous study released earlier this week showed that a Mediterranean diet lowered the risk of heart attack and stroke in people in Spain. But do these findings mean you should revamp your diet?

Experts say the Mediterranean diet is indeed "one of the healthiest diets on the planet," said Katherine Tallmadge, a dietitian and the author of "Diet Simple" (LifeLine Press, 2011).

But if you want to switch, you should first know exactly what eating a Mediterranean diet really means.

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"You don't just pour olive oil all over your dishes and think you're eating the Mediterranean diet," Tallmadge said.

Traditionally, a Mediterranean diet is a plant-based diet, meaning it's high in fruits, vegetables whole grains and legumes as well as fish, and very low in saturated fat and animal fat, Tallmadge said. Studies showing its benefits go back to the 1950s, Tallmadge explained. But even people in the Mediterranean are moving away from this traditional diet and adding more cheese and animal fat products to their meal plan, she said.

The main sources of fat in the traditional Mediterranean diet come from olive oil, nuts and fish, and these foods are eaten in moderation, said Heather Mangieri, a nutrition consultant and spokesperson for the American Dietetic Association. In the new study, people ate a handful of nuts each day, Mangieri said.

Because many Americans today eat a relatively poor diet nutrition-wise, even just incorporating a few aspects of the Mediterranean diet into their current way of eating would be a "massive improvement over what Americans are eating now," said Deborah Enos, a certified nutritionist and a health coach in the Seattle area.

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Mangieri agreed, saying that the best way to switch to a traditional Mediterranean diet is to start slowly by making a few changes, such as increasing the number of fruits and vegetables you consume every day, and eating a serving of fish once a week.

While nuts and seeds are a source of omega-3 fatty acids, a type of "healthy fat," it's not clear how much of this healthy fat we actually get by eating them, Mangieri said. That's because these foods actually contain alpha-linolenic acid, a compound our bodies convert to omega-3 fatty acids. It's unclear how efficient this process is, so the total amount of omega-3s we get from nuts and seeds may not be very much. Because of this, the best sources of omega-3s are fatty fish such as salmon, sardines and trout. Fish like salmon have more calories than white-fleshed fish, so limit your portion of the fatty fish to 3 to 4 ounces a serving, Mangieri said.

Studies also show that the olive oil sold in the United States may not be as healthful as olive oils sold in Mediterranean countries, Tallmadge said. Good-quality olive oil that has been freshly harvested and minimally processed (extra virgin) is high in compounds called polyphenols, which are thought to be responsible for the oil's health benefits, Tallmadge said. But a recent study from the U.S. Department of Agriculture found that olive oils sold in the United States were low in polyphenols, she said.

There are no quality standards for olive oil sold in the United States, Tallmadge added. But looking for an olive oil that says it's been harvested within the last year may increase the chance that it's higher in polyphenols, she said, since the level of polyphenols decreases with time.

It's important to note that the people in the new study were at risk for heart disease, so it's not clear if the results apply to healthy people. Also, the study did not consider exercise, which is an important part of a healthy lifestyle. "It’s a whole package deal," Mangieri said.

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