Antioxidant nutrients and exercise
Hard exercise raises free radicals that can damage muscle. Food antioxidants (vitamins C and E, carotenoids, polyphenols) help, but high-dose pills may blunt training gains.
Oxidative stress in exercise
Exercise raises oxygen use many times over. A small share of that oxygen forms reactive oxygen species (ROS): superoxide, hydrogen peroxide and the hydroxyl radical. When ROS outrun the body's defences, the result is oxidative stress: damage to membrane fats (lipid peroxidation), proteins and DNA, linked to muscle damage, soreness and fatigue. But moderate ROS are also signals: they switch on training adaptations such as new mitochondria and stronger antioxidant enzymes. So trained athletes build better natural defences.
The antioxidant defence system
| Type | Example | Nutrient link |
|---|---|---|
| Enzyme | Superoxide dismutase (SOD) | Zinc, copper, manganese |
| Enzyme | Catalase | Iron |
| Enzyme | Glutathione peroxidase | Selenium |
| Non-enzyme, water-soluble | Vitamin C; glutathione; uric acid | Vitamin C also regenerates vitamin E |
| Non-enzyme, fat-soluble | Vitamin E; beta-carotene and other carotenoids; coenzyme Q10 | Protect cell membranes |
| Plant compounds | Polyphenols and flavonoids; curcumin | From tea, turmeric, fruits, vegetables, cocoa |
Indian food sources of antioxidants
| Nutrient | Foods |
|---|---|
| Vitamin C | Amla, guava, oranges and sweet lime, drumstick leaves, capsicum, tomato |
| Vitamin E | Groundnuts, almonds, sunflower seeds, vegetable oils |
| Beta-carotene | Carrot, mango, papaya, pumpkin, green leafy vegetables |
| Selenium | Fish, eggs, whole grains, nuts |
| Zinc and copper | Pulses, nuts, whole grains, meat |
| Polyphenols | Turmeric, tea, jamun, pomegranate, onion, cocoa |
Food antioxidants vs high-dose supplements
Rather than antioxidant tablets, a cricketer in a long tournament gains more from two or three fruits and plenty of vegetables a day: amla or guava, carrot or papaya, a handful of groundnuts and turmeric in cooking. This supports recovery without blunting the training response.
2 marks: “What is oxidative stress?” An imbalance in which reactive oxygen species exceed the body's antioxidant defences, damaging lipids, proteins and DNA.
5 marks: “Explain the role of antioxidant nutrients in exercise.” How exercise produces free radicals, damage they cause, enzyme and nutrient defences with mineral cofactors, Indian food sources, and caution on high-dose supplements.
ACE + Se: vitamin A (beta-carotene), C, E and Selenium guard the cell.