Before summer ends, I relish the variety of wonderful fresh fruit and vegetables available in grocery stores and outdoor markets. There's no better treat than a succulent vine-ripened tomato or juicy watermelon. In addition to adding variety and flavor to our menus, each of these items also has nutritional value you may not know about.

As you walk the farmers' market trying to choose the best accompaniment for each meal, remember: The brighter and bolder the colors of fruits and vegetables, the more nutrients and phytochemicals they have. Fruits and vegetables are good sources of fiber and also add vitamin C, vitamin A, folate, iron, and calcium to your diet. Generally, fresh is best to ensure optimal levels of nutrients, but a few foods, such as tomato, corn, and carrot products, are better sources of phytochemicals when canned.

Here are some tips to help you navigate the produce section:

• Broccoli, cauliflower, kale, turnips, collards, Brussels sprouts, cabbage, kohlrabi and  rutabaga are good sources of isothiocyanates, a group of phytochemicals also known as mustard oil, and have been associated with a possible decreased risk of certain cancers.
  
  
• Tomatoes and watermelon are both rich in lycopene, a phytochemical that is associated with decreased risks of skin, breast, ovarian, lung, bladder, and prostate cancers and macular degeneration.
  
  
• Oranges, lemons, and limes contain limonoids. The role of limonoids in disease prevention is still uncertain, but they are thought to limit tumor formation.
  
  
• Raspberries strawberries, cranberries, pomegranates, and grapes are good sources of ellagic acid, which has been linked to reduced incidence of breast, pancreas, esophageal, skin, colon, and prostrate cancers.
  
  
• Summer squash and spinach, along with other yellow and dark green vegetables, are sources of beta carotene, which has been linked to a reduction in different types of cancers.
  
  
• Berries, plums, beets, purple grapes and eggplant are all sources of anthocyanins, a subgroup of flavonoids that may play a role in the prevention of coronary heart disease and also may inhibit a variety of carcinogens.

As I've discussed in other entries, it's not a good idea to forfeit succulent fresh produce because you're taking a supplement. All produce items are made up of hundreds of different phytochemicals that can contribute to your health and well-being. Many phytochemicals and their benefits have not been identified yet and relying on a supplement may prevent you from reaping all the benefits that fresh produce has to offer.