Does the nutritional content of the summer produce you eat pack enough of a healthy punch?

"You need to eat a wide variety of fruits and vegetables," said Luke Howard, University of Arkansas food science professor. "There are literally hundreds of compounds in fruits and vegetables that may be health-protective."

Howard attributes this quality to the different antioxidents found in the pigments of fruits and vegetables. Antioxidents help prevent the oxidative damage caused by free radicals in the body. Not all free radicals are bad. However, when more free radicals are present than the body's defense mechanism can take care of, an imbalance occurs and the free radicals have the potential to damage lipid membranes, proteins and DNA.

The rule of thumb: the more vibrant the color of the fruit or vegetable, the higher its antioxident level.

Howard recommends the following fruits and vegetables as powerhouse produce picks for the summer:

The Berry Bunch

The top three antioxident fruits are blueberries, blackberries and strawberries. The thing they have in common is the bright red, blue and purple colors that make up the class of pigments called "anthocyanins," which may help reduce the risk of cancer. These berries also contain ellagic acid, which also helps in cancer prevention. In addition, blackberries and strawberries provide an additional source of vitamin C.

Broccoli Is Better

Broccoli is one of the more nutritious produce items. It is from the class of cruciferous vegetables, which also includes radishes and kale. Broccoli contains several cancer protective compounds and is a source of beta-carotene, the precursor to vitamin A, and vitamin C. The cruciferous vegetables help lower cholesterol and maintain healthy immune systems.

Cell-Saving Carrots

Carrots are a good source of beta-carotene and alpha-carotene, which can help prevent cellular damage.

Re-Defining "Bad" Breath

Onion breath has good qualities after all! The smell that lingers in your mouth after eating onion and garlic is caused by sulfur compounds, which help lower cholesterol and maintain healthy immune systems. Onion also contains the pigment quercetin, a compound that protects against heart disease. Yellow and red onions are more nutritious than white onions because they contain more quercetin.

Some Like It Hot

Peppers contain a class of compounds called capsaicinoids. Capsaicinoids give peppers their spicy flavors. As with color, the more intense the flavor, the better the pepper is nutritionally. Additionally, peppers are one of the best sources of vitamin C.

Eye Candy

Though not a particularly good summer vegetable, spinach makes the list because it packs a lot of health-protective punch. The compound lutein contributes to the maintenance of healthy vision and protects against eye disorders like macular degeneration, which affects individuals age 65 years and older. Additionally, spinach is a good source of folic acid, which helps prevent such birth defects as spina bifida.

Replace lettuce with spinach on hamburgers and sandwiches for a healthier alternative, Howard suggests.

Picnic Staples

Tomatoes are a source of vitamin C and also contain the compound lycopene, which gives them their red color. Lycopene is an antioxidant that may protect against prostate cancer. The redder the tomato is, the more lycopene is contains.

Watermelon is as connected to summer as waterslides. This cool summer fruit is highly nutritious as well. Like tomatoes, watermelon contains lycopene. Ripe, red flesh is the best indication of the sweetest and most nutritious watermelon.