Antioxidants in preventing degenerative diseases
Antioxidants neutralise free radicals that damage fats, proteins and DNA. A diet rich in fruits, vegetables, nuts and spices helps prevent heart disease, cancer and cataract; high-dose pills do not.
Free radicals, oxidative stress and antioxidants
Free radicals are atoms or molecules with an unpaired electron, such as the superoxide and hydroxyl radicals. They form during normal metabolism and rise with smoking, pollution, UV light, infection, alcohol and high blood sugar. They attack cell membranes (lipid peroxidation), proteins and DNA. When free radicals outnumber the body's defences, the state is called oxidative stress. Antioxidants are substances that give an electron to a free radical or break the chain reaction, without becoming harmful themselves. The body makes antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) and gets others from food.
Antioxidants and their Indian food sources
| Antioxidant | How it works | Indian food sources |
|---|---|---|
| Vitamin C | Water-soluble; neutralises radicals in body fluids; regenerates vitamin E | Amla, guava, oranges, sweet lime, drumstick leaves, capsicum, cabbage |
| Vitamin E | Fat-soluble; protects cell membranes and LDL from oxidation | Sunflower and other vegetable oils, almonds, groundnuts, sunflower seeds, wheat germ |
| Beta-carotene and other carotenoids | Quench reactive oxygen; lycopene, lutein and zeaxanthin protect tissues and the eye | Carrot, papaya, mango, pumpkin, green leafy vegetables; tomato and watermelon (lycopene); spinach (lutein) |
| Selenium | Part of the enzyme glutathione peroxidase | Fish, eggs, whole grains, sunflower seeds |
| Zinc, copper, manganese | Needed by superoxide dismutase | Pulses, nuts, whole grains, meat |
| Polyphenols and flavonoids | Plant compounds that trap radicals and calm inflammation | Tea, onion (quercetin), apple, grapes, berries, cocoa, turmeric (curcumin), spices |
Role in degenerative diseases
| Disease | What free radicals do | How antioxidants help |
|---|---|---|
| Atherosclerosis and heart disease | Oxidise LDL, which forms foam cells and plaque | Vitamin E, carotenoids and polyphenols protect LDL |
| Cancer | Damage DNA, causing mutations | Fruits and vegetables are linked to lower risk of some cancers |
| Cataract and macular degeneration | Oxidise lens and retina proteins | Vitamin C, lutein and zeaxanthin from greens |
| Diabetes complications | High blood sugar increases oxidative stress in vessels and nerves | Good sugar control plus antioxidant-rich foods |
| Ageing and brain diseases | Cumulative damage to cells; linked to Alzheimer's and Parkinson's | Plant-rich diets are linked to slower decline |
Food or supplements?
The advice is 'food first': at least 400 g of fruit and vegetables a day (WHO), in many colours.
An antioxidant-rich day (sample menu)
| Meal | Menu | Antioxidants |
|---|---|---|
| Early morning | Green tea; 5 soaked almonds | Polyphenols, vitamin E |
| Breakfast | Vegetable poha with peanuts, carrot and peas; amla juice | Beta-carotene, vitamin E, vitamin C |
| Mid-morning | Guava or papaya | Vitamin C, carotenoids |
| Lunch | Brown rice, dal, drumstick leaves poriyal, tomato rasam, curd | Vitamin C, beta-carotene, lycopene |
| Evening | Turmeric milk; roasted sunflower seeds | Curcumin, vitamin E, selenium |
| Dinner | Chapati, fish or rajma curry, pumpkin and spinach sabzi | Selenium, zinc, carotenoids, lutein |
In heart, diabetes and cancer clinics, the dietitian adds colour to every plate (greens, orange and red vegetables, amla, guava) rather than prescribing antioxidant capsules, and advises patients on treatment to check with the doctor before any supplement.
2 marks: “What are free radicals?” Atoms or molecules with an unpaired electron that damage cell membranes, proteins and DNA, e.g. superoxide and hydroxyl radicals.
5 marks: “List dietary antioxidants with their food sources.” Vitamin C (amla, guava), vitamin E (oils, nuts), carotenoids (carrot, papaya, greens, tomato), selenium (fish, eggs), zinc (pulses), polyphenols (tea, onion, turmeric).
10 marks: “Discuss the role of antioxidants in preventing degenerative diseases.” Define free radicals, oxidative stress and antioxidants, body enzymes, dietary antioxidants table, role in atherosclerosis, cancer, cataract, diabetes, ageing, food vs supplements evidence, sample day.
'ACE + Selenium + Zinc': vitA (beta-carotene), vitC, vitE, plus selenium and zinc. Eat a rainbow, skip the mega-pills.