Antioxidant’s functions
Different kinds of antioxidants act as defensive organism against oxidative-stress. “Antioxidants are classified by function into four categories; Preventive antioxidants; radical scavenging antioxidants; repair and de novo antioxidants; and adaptation antioxidants” (Noguchi, Watanabe & Shi, p809).
Their functions are as follows:
- Antioxidants protect against cell injury
- They are involved in the prevention of aging, cancer and a variety of diseases.
- They act as hunters for the free radicals and help in reducing the toxicity of oxygen in the body (Noguchi, Watanabe & Shi, p809)
- Radical scavenging antioxidants have been explored to have a novel function by which they regulate gene expression.
Examples of antioxidants are vitamin C, vitamin E, superoxide dismutase, catalase, glutathione peroxidase, and ceruloplasmin. Also uric acid and bilirubin are known agents that act as antioxidants to aid in neutralizing a few specific free radicals. (Noguchi, Watanabe & Shi, p809)
Free radicals: How they affects the body
Free radicals in simple terms are just ions, atoms or groups of atoms with unpaired electrons in their last shell. These extremely reactive species start of autocatalytic reactions in which the molecules convert themselves into free radicals, and thus start a chain of further reactions. Free radical derivatives of oxygen – Reactive oxygen species or ROS, are of particular importance because of the use of oxygen to generate energy in the body. These include superoxide anions, hydrogen peroxide, and hydroxyl radicals. (Krogh, 506-540)
Free radicals are emerging as the final common pathway of cell injury in oxygen and other gaseous toxicity, chemical and radiation injury, inflammatory damage, tumor destruction by macrophages, cellular aging, killing of microorganisms by phagocytic cells and many others. (Krogh, 506-540)
Free radicals can cause:
- extensive damage to plasma and organellar membranes by their lipid peroxidation
- loss of mitochondrial function
- Lesions in DNA resulting in cell death or malignant transformation.
In addition free radicals are known to cause some problems with Parkinson’s disease, liver damage, senile and drug-induced deafness, schizophrenia, and also Alzheimer’s. “Radicals in cigarette smoke have been implicated in inactivation of alpha 1-antitrypsin in the lung which promotes the development of emphysema. (Krogh, 506-540)
Sources of Vitamin C
Many fruits and vegetables, including citrus fruits and berries, are rich in vitamin C. Foods that tend to be the highest sources of vitamin C include green peppers, guava, citrus fruits and juices, black currants, strawberries, tomatoes, broccoli, turnip greens and other leafy greens, sweet and white potatoes, melon and cantaloupe. Papaya, mango, watermelon, cauliflower, cabbage, winter squash, red peppers, raspberries, blueberries, cranberries, and pineapples are also good sources. Fresh vegetables and raw fruits have the most vitamins in them thus are considered as an easy source of vitamin. When they are cooked or even storage improperly, heat and light reduces the vitamin content thus provisions should be made to protect them.
Optimal delivery system for Vitamin C
The preferred delivery system for vitamin C comprises a slow release of the vitamin, providing a high, constant plasma concentration of the vitamin that is surprisingly effective for oxidative resistance. The delivery system may comprise of dosage units formulated for oral administration such as a hard or chewable tablet, capsule, granulates or powders.
RDA -recommends the following daily allowance for vitamin C. Men can take upto 90 mg while women can take upto 75 mg. However if these people smoke occasionally, then the recommendation allowance goes up by 35mg. (OHC, 2007)
Precautions for the use of Vitamin C
People are advised to use Vitamin C with caution in the following situations:
- People with kidney stones or a history of kidney stones should avoid doses of higher than 200mg. Kidney stone formation is likely if large doses are taken over long periods of time. It is further advised to consult the doctor before starting with a dose of vitamin C supplementation. (OHC, 2007)
- Lab test interference can be caught as false-positive for tests of diabetes if large dosages of vitamin C are consumed (OHC, 2007). Also, its use before certain types of tests for blood in the stool may cause false-negative results. (OHC, 2007)
- In pregnancy it is advised only when the potential benefits of vitamin C outweighs the possible hazards to the fetus. (OHC, 2007)
- Breastfeeding can be dangerous for the baby as traces of vitamin C can start to appear in the breast milk. (OHC, 2007)
- Over dosage of vitamin C can cause nausea, diarrhea, stomach cramps, skin rashes, and excessive urination. (OHC, 2007)
- Individuals taking anticoagulant, contraceptives and sulfonamides should consult their doctor before taking vitamin C supplements, as large doses of vitamin C may impact their efficacy. (Ford & Frey)
Works Cited
David Krogh, Biology: A Guide to the Natural World. Benjamin Cummings. (2008)
Ford-Martin, Paula; Frey, Rebecca. Gale Encyclopedia of Alternative Medicine. Gale, Cengage Learning. (2005). Web.
Noguchi, N; Watanabe, A and Shi, H. Diverse functions of antioxidants.PubMed. Free Radical Research. December Vol. 33(6) p. 809-17. (2000)
OHC. Vitamin C – Drug Interactions, Side Effects and Precautions of Use. Online Health Care. (2007). Web.