More research seems to come in every day showing just how crucial the food we eat is to our overall health and risk for disease. The latest: leafy greens and olive oil each reduce the risk of cardiovascular disease in women.

The new study followed almost 30,000 Italian women for an average of eight years. The researchers periodically asked them about their lifestyles and eating habits, including the types of foods they ate, with what frequency, how they were prepared, and the portion size.

Women who ate the most leafy green vegetables (at least one serving per day) had a 44% reduced risk of heart disease, compared to those who ate the least (two or fewer serving per week).

Since, as the authors point out, vegetable consumption in Italy is very much dependent upon the season, separate assessments were made in and out of the growing season. The women also answered questions about how much they exercised, smoked, their education level, and reproductive histories. The women were 50 years old, on average, when the study began.

The main outcome was whether the women suffered a heart attack, needed heart surgery, or died from any kind of heart-related problem.

Women who ate the most leafy green vegetables (at least one serving per day) had a 44% reduced risk of heart disease, compared to those who ate the least (two or fewer serving per week). Also, women who ate at least one ounce of olive oil per day were also about 40% less likely to suffer from heart problems than women who consumed the least (half an ounce or less per day). There was also a positive relationship between the amount of leafy greens a woman ate and the amount of olive oil she consumed. The exception to this rule was cooked tomatoes (i.e., tomato sauce), where the more cooked tomatoes a woman ate, the less olive oil she tended to consume. (The researchers point out that in Italy, eating tomato sauce and pasta frequently is correlated with an unhealthy diet that is high in meat and low in vegetables.)

There was no link between other types of vegetables and heart disease, and the researchers found no connection between fruit and heart disease risk.

The authors point out that earlier studies in the U.S. have linked greater vegetable and fruit consumption with lower risk for coronary heart disease. They suggest that the reason their study found no connection between fruit and heart disease may have been due to its Italian setting. Unlike the U.S., where fruit consumption is closely linked to healthy diet and lifestyle, in Italy, eating fruit is "deeply rooted in the daily habits of the general population, including individuals with unhealthy dietary pattern." So people who ate a lot of fruit in the current study may not have led an otherwise healthy lifestyle at all.

What’s behind the heart benefits seen here? It’s likely the high levels of folate, potassium, and antioxidants in leafy greens that protect that heart. As for the olive oil, the polyphenol compounds are probably responsible for the heart-healthy effects.

While more research is being done to figure out exactly how greens, olive oil, and the heart are interconnected, it’s probably a safe bet to grab some spinach or kale and drizzle on a little olive oil for dinner tonight.

The research was carried out at the Cancer Research and Prevention Institute in Florence and published in the December 22, 2010 online issue of The American Journal of Clinical Nutrition.