DEAR PEGGY: Do vegetables lose vitamins when boiled? If so, is it an appreciable amount? —M.S., San Diego, California
Nutrients escape from vegetables in two ways: They dissolve in cooking water or they're destroyed by heat. The simplest ways to minimize this loss is to include the cooking liquid when serving the dish or to choose a cooking method that doesn't involve much water.
When you boil vegetables, minimize the loss of vitamin C by adding them to the water after it comes to a boil. Another way to reduce the loss of water-soluble vitamins and volatile nutrients is to cook vegetables, covered, in a minimum amount of water.
Rapid cooking techniques, such as stir-frying, can help preserve some thiamin and vitamin C, which are most susceptible to destruction by heat. Another tip is to cut vegetables into small pieces to reduce cooking time.
When all is said and done, however, nutritional differences don't vary greatly from one cooking method to another. Vegetables only lose 5 to 10 percent of their minerals no matter how they're prepared. That's why it's best to simply choose a cooking method that yields the flavor, appearance and texture you prefer most in your vegetables.