Plants are also prone to cancer and viruses because of this they have developed their own protective substances called phytochemicals (phyto is a Greek word for plant). This same substance can also protect human against cancer, diabetes, cardiovascular disease, prevent cell damage, and other diseases. It is estimated that there may be more than 100 different protective plant chemicals in just one serving of vegetables.

Protective Plant chemicals:

• Allylic sulfides - it function to stimulate production of protective enzymes. Sources: garlic, onions, chives and leeks.
• Bioflavonoids - Antioxidant, inhibit cancer promoting hormones. Sources: most fresh fruits and vegetables.
• Carotenoids - Antioxidant that help protect cells from free radicals. Sources: carrots, watermelon, red grapefruit, guava, processed tomatoes and red capsicum.
• Catechins (tannins) - Antioxidant. Sources: Berries, green tea.
• Curcumin - Protects against tobacco-induced carcinogens. Sources: Turmeric, cumin.
• Genistein - Inhibits tumor growth. Sources: Broccoli and other cruciferous vegetables.

• Indoles - Inhibit estrogen, which stimulates some cancers; induce protective enzymes. Sources: Broccoli, cabbage, cauliflower; mustard greens.
• Isoflavones - Inhibit estrogen uptake; destroy cancer enzymes. Sources: Beans, peanuts and other legumes, peas.

• Isothiocyanates - Induce production of protective enzymes. Sources: Horseradish, mustard, radishes.
• Lignans - Inhibit estrogen and block prostaglandins. Sources: Fatty fish, flaxseed, walnuts.
• Limonoids - Induce protective enzymes. Sources: Citrus fruits (lemons, oranges, grapefruits).
• Lycopene - Antioxidant; may protect against prostate cancer. Sources: Pink grapefruits, tomatoes, watermelon.
• Monoterpenes - Some antioxidant properties; aid in activity of protective enzymes. Sources: Basil, citrus fruits, broccoli, orange and yellow vegetables
• Omega-3 fatty acids - Inhibit estrogen; reduce inflammation. Sources: Canola oil, flaxseed, walnuts, fatty fish
• Phenolic acid - Inhibits nitrosamines; enhances enzyme activity. Sources: Berries, broccoli, cabbage, carrots, citrus fruits, eggplant, parsley, peppers, teas, tomatoes, whole grains.
• Protease - Destroys enzyme inhibitors that promote cancer to spread. Sources: Soybeans
• Quercetin - Inhibits cellular mutation, carcinogens, clot formation, and inflammation. Sources: Grape skins, red wine.