An atom is a small and unique unit of matter having a nucleus and electrons. Atoms exist
together with other atoms as molecules. During metabolism, molecules break apart and their
atoms lose electrons; this process is usually fuelled by oxygen and is called oxidation.
Free radicals are formed during oxidation when a stable atom loses or gains an electron and this
electron remains unpaired. Free radicals can be produced when ATP is formed, when our
immune system fights infections, and when we are exposed to pollution, toxic substances,
radiation, the sun, and tobacco smoke. Free radicals are highly unstable entities that cause the
production of more free radicals. They can damage our cell membranes, LDLs, cell proteins and
DNA and are associated with many diseases, including heart disease, cancer and diabetes.
Antioxidant vitamins donate electrons or hydrogen atoms to free radicals to stabilize them and
reduce oxidative damage. Antioxidant minerals are part of antioxidant enzyme systems that
convert free radicals to less damaging substances, which our bodies then excrete. Other
compounds stabilize free radicals, which prevent them from damaging cells and tissues.
Selenium, copper, iron, zinc and manganese act as cofactors for the antioxidant enzyme systems,
allowing the enzymes to function properly. Superoxide dismutase, catalase and glutathione
peroxide are examples of antioxidant enzymes.
Vitamin E protects our cell membranes from oxidation, enhances immune function, and
improves our absorption of vitamin A if dietary intake is low. The RDA for vitamin E is 15 mg
alpha-tocopherol per day for men and women. Vitamin E is found primarily in vegetable oils and
nuts. Toxicity is uncommon, but taking very high doses can cause excessive bleeding.
Deficiency is rare, but symptoms include anemia and impaired vision, speech and movement.
Vitamin C scavenges free radicals and regenerates vitamin E after it has been oxidized. Vitamin
C prevents scurvy and assists in the synthesis of collagen, hormones, neurotransmitters and
DNA. Vitamin C also enhances iron absorption. The RDA for vitamin C is 90 mg per day for
men and 75 mg per day for women. Many fruits and vegetables are high in vitamin C. Toxicity is
uncommon; symptoms include nausea, diarrhea and nosebleeds. Deficiency symptoms include
scurvy, anemia, diarrhea and depression.
Beta-carotene is a carotenoid and a provitamin of vitamin A. It protects the lipid portions of our
cell membranes and LDL cholesterol from oxidative damage. It also enhances our immune
function and protects our vision. There is no RDA for beta-carotene. Orange, red and deep green
fruits and vegetables are good sources of beta-carotene. There are no known toxicity or
deficiency symptoms, but yellowing of the skin can occur if too much beta-carotene is