The U.S. Department of Agriculture recommends that adults on a typical 2,000-calorie diet eat 2 1/2 cups of vegetables and 2 cups of fruits each day -- and for good reason. Fruits and vegetables supply you with a host of beneficial nutrients, including the vitamins, minerals, fiber and phytochemicals your body needs to maintain optimal function. Not getting the recommended amounts can result in nutrient deficiencies and poor health.

Fruits and vegetables are a major source of important nutrients in the diet, including vitamins A, C, E and K, the mineral potassium and the indigestible carbohydrate fiber. Lacking any one of the nutrients can lead to poor health. For example, you need vitamin C to maintain tissue health and to aid in wound healing; vitamin A supports eye health; vitamin E is a strong antioxidant vitamin that helps fight damaging free radicals in the body; and vitamin K is essential for proper blood clotting. The mineral potassium is an essential electrolyte that helps regulate fluids in the body and counteracts the negative effects of too much sodium, another electrolyte, in the diet. Lastly, fiber, the indigestible part of fruits and vegetables, promotes digestive health and can help reduce high cholesterol.

A study conducted by Harvard University -- the largest study of its kind at the time of publication -- followed 110,000 adults for 14 years and found that the higher the intake of fruit and vegetables, the lower the risk of developing cardiovascular disease. Study participants who consumed 8 cups of produce each day had a 30 percent lower risk of heart attack or stroke compared with those who ate less than 1 1/2 cups.

As a whole, fruits and vegetables, especially non-starchy types with high water content, are the most nutrient dense, yet the least calorically dense of any of the food groups. They are often referred to as low-energy-dense foods, because they contain few calories per gram compared to other foods. This means that you can eat a lot of them and fill up on fewer calories than other food groups, like grains. They're also high in fiber, which helps fill you up and keeps you satiated until your next meal. If you don't eat fruits and vegetables, you may find yourself eating too many calories from other food groups, yet not feeling full. This makes it difficult to manage your weight.

It's important to first understand what constitutes a cup of vegetables so that you can include more in your diet. For most veggies and fruits, like broccoli, apples, squash, red peppers and bananas, a cup or one medium piece of fruit is one serving. However, for leafy greens, like spinach, butterhead lettuce and romaine, 2 cups is one serving. Dried fruits are condensed sources of natural sugars; 1/2 cup of dried fruit is equivalent to one serving of fresh.

Keep in mind that all vegetables are not created equal. Starchy vegetables, like potatoes and corn, are more energy dense, so they'll pack more of a caloric punch. Make non-starchy vegetables the focus of your meal. And, remember to eat vegetables in a wide array of colors; each color signals a different phytonutrient content, such as beta-carotene in orange vegetables -- and all of them are important to your health.