- Vitamin A (retinol), also synthesized by the body from beta-carotene, protects dark green, yellow and orange vegetables and fruits from solar radiation damage, and is thought to play a similar role in the human body. Carrots, squash, broccoli, sweet potatoes, tomatoes (which gain their color from the compound lycopene), kale, seabuckthorn, collards, cantaloupe, peaches and apricots are particularly rich sources of beta-carotene.
- Vitamin C (ascorbic acid) is a water-soluble compound that fulfills several roles in living systems. Important sources include citrus fruits (such as oranges, sweet lime, etc.), green peppers, broccoli, green leafy vegetables, black currants, strawberries, blueberries, seabuckthorn, raw cabbage and tomatoes. Linus Pauling was a major advocate for its use.
- Vitamin E, including tocotrienol and tocopherol, is fat soluble and protects lipids. Sources include wheat germ, seabuckthorn, nuts, seeds, whole grains, green leafy vegetables, vegetable oil, and fish-liver oil. Alpha-tocopherol is the main form in which vitamin E is consumed. Recent studies showed that some tocotrienol isomers have significant anti-oxidant properties.
Vitamin cofactors and minerals
- Lycopene - found in high concentration in ripe red tomatoes.
- Lutein - found in high concentration in spinach and red peppers.
- Beta-carotene - found in high concentrations in butternut squash, carrots, orange bell peppers, pumpkins, and sweet potatoes.
- Zeaxanthin - the main pigment found in yellow corn.
- Astaxanthin - found naturally in red algae and animals higher in the marine food chain. It is a red pigment familiarly recognized in crustacean shells and salmon flesh/roe.
Flavonoids, a subset of polyphenol antioxidants, are present in many berries, as well as in coffee and tea.
Phenolic acids and their esters
- Ellagic acid - found in high concentration in raspberry and strawberry, and in ester form in red wine tannins.
- Gallic acid - found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and many other plants.
- Salicylic acid - found in most vegetables, fruits, and herbs; but most abundantly in the bark of willow trees, from where it was extracted for use in the early manufacture of aspirin.
- Rosmarinic acid - found in high concentration in rosemary, oregano, lemon balm, sage, and marjoram.
- Cinnamic acid and its derivatives, such as ferulic acid - found in seeds of plants such as in brown rice, whole wheat and oats, as well as in coffee, apple, artichoke, peanut, orange and pineapple.
- Chlorogenic acid - found in high concentration in coffee (more concentrated in robusta than arabica beans), blueberries and tomatoes. Produced from esterification of caffeic acid.
- Chicoric acid - another caffeic acid derivative, is found only in the popular medicinal herb Echinacea purpurea.
- Gallotannins - hydrolyzable tannin polymer formed when gallic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose.
- Ellagitannins - hydrolyzable tannin polymer formed when ellagic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose.
Other nonflavonoid phenolics
Other organic antioxidants
- Citric acid, oxalic acid, and phytic acid
- Lignan - antioxidant and phytoestrogen found in oats, flax seeds, pumpkin seeds, sesame seeds, rye, soybeans, broccoli, beans, and some berries.
- Bilirubin, a breakdown product of blood, has been identified as a possibly significant antioxidant.
- Uric acid In humans accounts for roughly half the antioxidant ability of plasme.
- R-α-Lipoic acid - fat and water soluble
- N-Acetylcysteine - water soluble
Many common foods are good sources of antioxidants. In the list of foods given below, rich in anti-oxidants usually means at least a ORAC rating of 1000 per 100 g. A typical apple or pear weighs around 200 g and hence 200 g can be considered as the serving size.
Spices, herbs, essential oils and cocoa are rich in anti-oxidant properties but the serving size is too small to be the top-contributors of anti-oxidants. Typical spices high in anti-oxidants are cinnamon, oregano, turmeric, cumin, parsley, basil, curry powder, mustard seed, ginger, pepper, chili powder, paprika, garlic, coriander, onion and cardamom. Typical herbs are sage, thyme, marjoram, tarragon, peppermint, oregano, savory, basil and dill weed.
Dried fruits are a good source of anti-oxidants by weight/serving size as the water has been removed making the ratio of anti-oxidants higher. Typical dried fruits are pears, apples, plums, peaches, raisins, figs and dates. Dried raisins are high in polyphenol count. Red wine is high in total anti-oxidants count as well as polyphenol count.
Sorghum bran, cocoa powder, and cinnamon are rich sources of procyanidins, which are very large compounds found in many fruits and some vegetables and that have been shown to be beneficial for health in humans. Because of the large size of these compounds, the amount that is actually absorbed into the body is thought to be low. These compounds can be degraded by bacteria in the gastrointestinal tract. Crude rice bran and other cereals like corn-flakes, oats and granola are also a good source of anti-oxidants.
Nuts are a rich source of anti-oxidants. Typical nuts are pecans, walnuts, hazelnuts, pistachio, almonds, cashew nuts, macademia nuts and peanut Butter.
Fleshy fruits like cranberries, blueberries, plums, peaches, blackberries, raspberries, apples, strawberries, red currants, figs, cherries, gooseberry (not to be confused with Indian gooseberry which also has strong claims), pears, guava, peaches, oranges, apricots, mango, grape juice and pomegranate juice also rated highly on the ORAC scale.
Typical cooked vegetables rich in anti-oxidants are artichokes, cabbage, broccoli, asparagus, avocados, beetroot, radish, potato and raw lettuce and frozen spinach.