There's no doubt vegetables have lots of good nutrition to offer, but how you purchase, store, and prepare them can dramatically affect their value.  Here's what you need to know when cooking up your favorite veggies.

As soon as vegetables are picked, their nutrient clock beings to tick away. The more time it spends off the plant, the more vitamins will be lost.

For this reason, seeking out local produce when possible is never a bad idea -- the less time it takes for the veggies to get to your plate, the more nutrients they'll retain. Support local agriculture in your community or get your hands dirty by planting some of your own herbs and vegetables – you can't get more local than that.

Once you get those fresh vegetables home, minimize additional nutrient loss by eating them right away or storing in the refrigerator or freezer. Cold temperatures will limit the degradation of vitamins so use the vegetable drawer in your fridge (where humidity is higher) and store in an air-tight bag or container. Avoid trimming and chopping prior to storage too, this will limit surface area and help lock more of the vitamins inside.

Cooking veggies can further diminish the content of various water-soluble vitamins including folate, thiamin, B6 and vitamin C, especially in foods that sit out heated for more than 2 hours (think buffet or cafeteria style). Vitamin A, riboflavin and niacin tend to hang in there a bit better, while fiber and minerals will remain virtually unaffected.

Overcooked veggies are better than no veggies at all BUT quick cooking will maximize nutrients. Take advantage of as many vitamins as possible by following these tips:

• Keep skins on when possible
• Avoid continuous reheating of food
• Use a minimal amount of cooking liquid
• Choose steaming over boiling
• When you do boil, retain the cooking liquid for a future use (like soups and stocks)
• Use the microwave 
• Use a pressure cooker when possible
• Avoid using baking soda to retain color
• Cut veggies into large chunks to reduce surface area

Dana Angelo White, MS, RD, ATC, is a registered dietitian, certified athletic trainer and owner of Dana White Nutrition, Inc., which specializes in culinary and sports nutrition. See Dana's full bio »