in food industry - food preservatives
- Ascorbic acid (vitamin C)
- Tocopherol-derived compounds
- BHA, BHT, EDTA
- Citric acid
- Acetic acid - found in vinegar; used for pickling
- Rosmarinic acid - in the form of the herb rosemary and Italian seasoning mixtures in naturally or minimally processed foods, and pet foods
Since the discovery of vitamins, it has been recognized that antioxidants from the diet are essential for healthful lives in humans and many other mammals. More recently, a large body of evidence has accumulated that suggests supplementation of the diet with various kinds of antioxidants can improve health and extend life. Many nutraceutical and health food companies now sell formulations of antioxidants as dietary supplement. These supplements may include specific antioxidant chemicals, like resveratrol (from grape seeds), combinations of antioxidants, like the "ACES" products that contain beta carotene (provitamin A), vitamin C, vitamin E and Selenium, or specialty herbs that are known to contain antioxidants such as green tea and jiaogulan.
There are hundreds of different types of antioxidants. The following substances may have nutritional antioxidant effects:
- 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, 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. Recent studies showed that some tocotrienol isomers have significant anti-oxidant properties.
- Coenzyme Q10 (CoQ10) is an antioxidant which is both water and lipid soluble. It is not classified as a vitamin in humans as it can be manufactured by the body, but quantities decrease with age to levels that may be less than optimal, and levels in the diet are generally low. Supplementation with CoQ10 has been clinically proven to improve the health of gums. There is evidence that CoQ10 helps protect the brain against Parkinson's disease.
- Manganese, particularly when in its +2 valence state as part of the enzyme called superoxide dismutase (SOD).
- Melatonin is a natural hormone, occurring in every organism, which has many biological roles. Melatonin acts as an antioxidant and promoter of antioxidants in several different ways. Recent research supports a specific role as an antioxidant in mitochondria, which have an high level of reactive oxygen species produced during aerobic metabolism, but lack some of the protective mechanisms of cell nuclei.
See main article at Carotenoid
- 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.
Eugenol - has by far the highest Oxygen Radical Absorbance Capacity (ORAC) of all foodborn substances (in clove oil). Its concentration in clove oil ranges 5-20 times greater than where it is found in other sources such as in basil and cinnamon.