We need oxygen to survive: our bodies rely on it for proper function of body cells, metabolism, and producing energy. But in the process of being used by the body, oxygen can produce harmful byproducts, called free radicals. Free radicals are atoms with an odd (unpaired) number of electrons that are highly reactive. They can bind to DNA molecules, and damage or kill cells by binding to their protective membranes. It's the same thing that happens when oils turn rancid, peeled apples turn brown, and iron turns to rust. Antioxidants protect the cells by binding with the free radicals and neutralizing them before they can cause any damage.
Cell damage is the root cause of most age-related health problems. If left unchecked, free radicals may cause arthritis, heart damage, cancer, stroke, cataracts, or a weakened immune system, and may play a role in the development of Alzheimer's disease. Scientists believe free radicals may also speed up hardening of the arteries. It's impossible to avoid all damage by free radicals, but consuming antioxidants can help reduce it.
The four most common antioxidants are vitamins E and C, beta-carotene, and selenium. It is best to get your daily dose through food instead of supplements. For vitamin E, look to walnuts, peanuts, almonds, olives, avocado, wheat germ, and liver. Leafy green vegetables are an excellent source of both vitamin E and vitamin C. Citrus fruits, tomatoes, peppers, potatoes and broccoli can also boost your vitamin C intake. Common sources of beta-carotene include mangoes, papaya, pumpkin, spinach, kale, squash and apricots. Finally, you can get your required dose of selenium by eating seafood, beef, pork, chicken, brown rice, and whole wheat bread.