What Are RDAs?
RDAs, or recommended dietary allowances, are established by the Food and Nutrition Board, which is part of the National Academy of Sciences. These guidelines suggest the amounts of the various nutrients you should ingest daily. "If you get a nutrient at the RDA level, you're almost certain to be getting enough," says Linda D. Meyers, Ph.D., director of the Food and Nutrition Board. "It's set up to meet the needs of virtually everyone."

What Are Antioxidants?
Antioxidants are chemical agents in the body that protect cells against damage caused by free radicals. Some researchers believe the antioxidant nutrients (like vitamins C and E) help prevent disease.

What Are Free Radicals?
These are atoms or molecules that circulate throughout the body; they can damage certain types of tissue and even DNA. Free radicals may contribute to hardening of the arteries, the aging process, and cancer.