"Eat your fruits and vegetables" is one of the tried and true recommendations for a healthy diet. And for good reason. Eating plenty of fruits and vegetables can help you ward off heart disease and stroke, control blood pressure and cholesterol, prevent some types of cancer, avoid a painful intestinal ailment called diverticulitis, and guard against cataract and macular degeneration, two common causes of vision loss.

What does "plenty" mean? More than most Americans consume. If you don't count potatoes - which should be considered a starch rather than a vegetable - the average American gets a total of just three servings of fruits and vegetables a day. The latest dietary guidelines call for 5 to 13 servings of fruits and vegetables a day, depending on one's caloric intake.(1) For a person who needs 2,000 calories a day to maintain weight and health, this translates into nine servings, or 4½ cups per day. Over the past 30 years or so, researchers have developed a solid base of science to back up what generations of mothers preached (but didn't always practice themselves). Early on, fruits and vegetables were acclaimed as cancer-fighting foods. In fact, the ubiquitous 5-A-Day message (now quietly changing to Eat 5 to 9 A Day) seen in produce aisles, magazine ads, and schools is supported in part by the National Cancer Institute. The latest research, though, suggests that the biggest payoff from eating fruits and vegetables is for the heart.

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Fruits, Vegetables, and Cardiovascular Disease There is compelling evidence that a diet rich in fruits and vegetables can lower the risk of heart disease and stroke. The largest and longest study to date, done as part of the Harvard-based Nurses' Health Study and Health Professionals Follow-up Study, included almost 110,000 men and women whose health and dietary habits were followed for 14 years. The higher the average daily intake of fruits and vegetables, the lower the chances of developing cardiovascular disease. Compared with those in the lowest category of fruit and vegetable intake (less than 1.5 servings a day), those who averaged 8 or more servings a day were 30% less likely to have had a heart attack or stroke.(2) Although all fruits and vegetables likely contribute to this benefit, green leafy vegetables such as lettuce, spinach, Swiss chard, and mustard greens; cruciferous vegetables such as broccoli, cauliflower, cabbage, Brussels sprouts, bok choy, and kale; and citrus fruits such as oranges, lemons, limes, and grapefruit (and their juices) make important contributions.

Fruits and Vegetables, Blood Pressure, and Cholesterol High blood pressure is a primary risk factor for heart disease and stroke. As such, it's a condition that is very important to control. Diet can be a very effective tool for lowering blood pressure. One of the most convincing associations between diet and blood pressure was found in the Dietary Approaches to Stop Hypertension (DASH) study. (3) This trial examined the effect on blood pressure of a diet that was rich in fruits, vegetables, and low-fat dairy products and that restricted the amount of saturated and total fat. The researchers found that people with high blood pressure who followed this diet reduced their systolic blood pressure (the upper number of a blood pressure reading) by about 11 mm Hg and their diastolic blood pressure (the lower number) by almost 6 mm Hg - as much as medications can achieve. Eating more fruits and vegetables can also help lower cholesterol. In the National Heart, Lung, and Blood Institute's Family Heart Study, the 4466 subjects consumed on average a shade over 3 servings of fruits and vegetables a day. Men and women with the highest daily consumption (more than 4 servings a day) had significantly lower levels of LDL (bad) cholesterol than those with lower consumption.(4) How fruits and vegetables lower cholesterol is still something of a mystery. It is possible that eating more fruits and vegetables means eating less meat and dairy products, and thus less cholesterol-boosting saturated fat. Soluble fiber in fruits and vegetables may also block the absorption of cholesterol from food.