It is ironic that oxygen, which is indispensable for life, under certain situations has harmful effects on the body, due to the formation of reactive oxygen species (ROS) by chemical reactions. To understand anti-oxidants, we need to first know about Free radicals or ROS. Free radicals are generated by our body through various chemical interactions- both normally and during illness. At moderate concentrations, ROS are necessary for the maturation process of cellular structures and can act as weapons for the host defense system. When an overload of free radicals cannot gradually be destroyed, their accumulation in the body generates a phenomenon called oxidative stress, adversely altering lipids, proteins, and DNA and triggering a number of human diseases. Oxidative stress plays a role in causing many conditions, including atherosclerosis, inflammatory condition, certain cancers, and the process of aging. Anti-oxidants are those molecules that neutralize these harmful free radicals thus promoting health. A balance between free radicals and antioxidants is necessary for proper physiological function.
Source of anti-oxidants:
Anti-oxidants are produced within the body (endogenous anti-oxidants) and also present in food (Dietary anti-oxidants)
- Endogenous anti-oxidants:
Cells can be classified as enzymatic antioxidants and non-enzymatic antioxidants. Some such antioxidants glutathione, ubiquinol, and uric acid are produced within the body.
- Dietary anti-oxidant:
The principal micronutrient antioxidants which have to be supplied through diet are vitamin E, vitamin C, lycopene, B-carotene, omega 3 and omega 6 fatty acids. Strong antioxidant activities have been found in berries, cherries, citrus, prunes, and olives. Green and black teas have been extensively studied in the recent past for antioxidant properties. Broccoli, carrots, and tomatoes are considered functional foods because of their high contents of physiologically active components. The dietary sources of vitamin E are vegetable oils, wheat germ oil, whole grains, nuts, cereals, fruits, eggs, poultry and meat. Beta-carotene is present in many fruits, grains, oil and vegetables (carrots, green plants, squash, spinach). The major dietary source of lycopene is tomatoes. The main natural sources of flavonoids include green tea, grapes (red wine), apple and cocoa.
- Omega 3 and Omega 6 fatty acids:
Omega-3s reduce inflammation and prevent chronic ailments such as heart disease, stroke, memory loss, depression, arthritis, cataract and cancer and can be found in fatty fish (salmon, tuna, halibut, sardines, pollock), krill, algae, walnut, nut oils and flaxseed. Omega-6s improve diabetic neuropathy, eczema, psoriasis, osteoporosis, and aid in cancer treatment its dietary sources include vegetable oils, nuts, cereals, eggs and poultry. A healthy diet should consist of about 2-4 times more omega-6s than omega-3s.
Antioxidant supplements are compounds obtained either by extraction from natural foods or by chemical synthesis. Although many epidemiological data suggest that antioxidants may have a beneficial effect on many chronic diseases, the systematic use of supplements is hindered by several factors: the lack of prospective and controlled studies, the long-term effects and the dosages necessary for each type of disease. Also, antioxidant supplements can act as pro-oxidants e.g., as oxidative stress inducers if they are consumed at levels significantly above the recommended dietary intakes (RDI). Taking supplements in high doses can be harmful and always consult a healthcare professional about combining a dietary supplement with conventional medical treatment.
Take home message:
If possible, it is best to get the antioxidants from a diet rich in fruits and vegetables. Anti-oxidant supplements are to be used only when medically indicated or when the natural source is unavailable as in the case of soldiers and sailors.
Dr. Sujith. M. S | Consultant – Physician | Narayana Multispeciality Hospital, HSR Layout, Bangalore