It’s no secret that eating well is good for both body and mind, so it may not come as a surprise that a new study finds women who eat more olive oil and leafy vegetables such as salads and cooked spinach are significantly less likely to develop heart disease.

A group of Italian researchers found that women who ate at least 1 serving of leafy vegetables per day were more than 40 percent less likely to develop heart disease over an average of eight years, relative to women who ate two or fewer portions of those vegetables each week.

Women who downed at least 3 tablespoons of olive oil daily - such as in salad dressing - were also 40 percent less likely to be diagnosed with heart disease, compared to women who ate the least olive oil.

It’s not exactly clear why specifically leafy vegetables and olive oil may protect the heart, study author Dr. Domenico Palli of the Cancer Research and Prevention Institute in Florence told Reuters Health. “Probably the mechanisms responsible for the protective effect of plant-origin foods on cardiovascular diseases involve micronutrients such as folate, antioxidant vitamins and potassium, all present in green leafy vegetables.”

Folate reduces blood levels of homocysteine, Palli explained, which is thought to increase the risk of cardiovascular disease by damaging the inner lining of arteries. Other studies have shown people who eat more potassium have lower blood pressure, which can protect the cardiovascular system. Virgin olive oil may be particularly effective at lowering heart disease risk because of its high level of antioxidant plant compounds, he added.

This is not the first study to link olive oil or vegetables to good heart health. Most famously, the traditional Mediterranean diet - rich in vegetables and monounsaturated fats from olive oil and nuts, but low in saturated fat from meat and dairy - has been tied to a decreased risk of heart disease.

Mediterranean-style eating has also been credited with lowering risk for some cancers, diabetes, and, more recently, with slowing brain aging (See Reuters Health story of December 29, 2010).

Cardiovascular disease is a major killer, responsible for 30 percent of all deaths worldwide and the leading cause of death for both men and women in the U.S.

To look more closely at the role of foods in protecting against heart disease, Palli and colleagues reviewed dietary information collected from nearly 30,000 Italian women participating in a large national health study. Researchers followed the women, whose mean age was 50 at the beginning of the study, for an average of 8 years, noting who developed heart disease.

In that time, the women experienced 144 major heart disease-related events, such as heart attack or bypass surgery, the authors report in the American Journal of Clinical Nutrition.

Women who ate at least one daily serving (about two ounces) of leafy vegetables - such as raw lettuce or endives, or cooked vegetables like spinach or chard - had a 46 percent lower risk of developing heart disease than women who ate at most two portions per week.

Consuming at least an ounce of olive oil per day lowered their risk by 44 percent relative to women who consumed a half-ounce or less daily, the authors found.

The women’s intake of other types of vegetables, such as roots and cabbages, and their consumption of tomatoes or fruit did not seem to be linked to their risk for major heart events.

Both fruits and vegetables have been associated with heart benefits in past studies conducted elsewhere in Europe and in North America. The authors caution that the apparent lack of positive effect from high fruit consumption in their results may have something to do with a different attitude toward fruit in Italy. It is cheap, varied and easily available, so eating a lot of fruit is a widespread habit but it does not necessarily signal that the rest of someone’s diet is as healthy, the authors wrote.

Another issue with the study, Palli noted in an e-mail, is that women had to report how much they ate of various items, and some may not have remembered their diets accurately, or may have changed their eating habits during the study period. In addition, people sometimes over-estimate their healthy behaviors, believing they eat healthier than they really do.

SOURCE: American Journal of Clinical Nutrition, published online December 22, 2010.