New research shows that disease-fighting plant compounds called phytochemicals may play a big role in preventing many cancers and heart disease, so it's not surprising that nutrition-supplement makers have begun marketing concentrated phytochemical tablets geared to both adults and kids.

Should you get some for the whole family? No, say most experts. There hasn't been enough research on the effects of concentrated doses of phytochemicals, particularly in children. In fact, too much may be a bad thing. Take sulforaphane, a phytochemical believed to inhibit cancer growth. "Along with slowing the growth of tumor cells, extra sulforaphane, or high doses of broccoli-concentrate pills that contain sulforaphane could also slow normal cell development, affecting a child's overall growth," says Dr. John Milner, head of the department of nutrition at Pennsylvania State University. Plus, phytochemical supplements are expensive and lack the other beneficial nutrients found in vegetables and fruits, such as fiber.The best way to ensure that you and your kids benefit from these plant compounds: Eat fruits and vegetables - about five to nine servings a day for adults; five for children under age 6. In fact, you can tailor your family's diet according to a particular risk. If you have a family history of cancer, for instance, you might eat more sulforaphane, found in cruciferous vegetables such as broccoli, brussels sprouts and cauliflower.

While eating more of these compounds is no guarantee against illness, every little bit helps. And since a lifelong diet of fruits and vegetables may actually lower your child's risk for so many diseases, why not start now?