What Are Antioxidants?
Fortunately, other molecules can protect cells against the effects of oxidative damage. Antioxidants are a class of molecules that inhibit the oxidation of other molecules. By neutralizing ROS, antioxidants may slow or even reverse the effects of oxidative damage. This may provide an important mechanism by which antioxidants can reduce the risk of chronic disease.
The body naturally produces some antioxidants, including glutathione, coenzyme Q (CoQ), uric acid, bilirubin, melatonin, and alpha-lipoic acid (ALA) (Rizzo et al., 2010). Other antioxidants are found in dietary sources. Consuming more antioxidant-rich foods can boost your body’s antioxidant activity and may reduce risk of disease.
Types of Antioxidants that Benefit Health
There are at least several hundred — and perhaps thousands — of compounds that have antioxidant activity in the human body (Getz, 2008). Dozens of compounds with antioxidant properties are discovered each year. Some of the most well-characterized antioxidants include:
Resveratrol. Resveratrol is a phytochemical, or plant chemical, found in high concentrations in the skins of red grapes. Resveratrol contributes to cardiovascular health by promoting lipid metabolism, reducing “bad” LDL cholesterol levels, and preventing platelets from aggregating into clots (Fremont, 2000). Additionally, resveratrol may have anti-cancer properties and may reduce inflammation within cells.
Sulforaphane. Cruciferous vegetables, such as Brussels sprouts, broccoli, and cabbages are high in sulforaphane. Sulforaphane, a type of organosulfur compound, has potent antioxidant effects. It has been linked to lower risk of colon cancer and may also be effective in prevention of skin cancer (de Figueiredo et al., 2015).
Lycopene. Lycopene, found in tomatoes, has antioxidant properties that improve overall cardiovascular health, and certain tomato products that are cooked like sun-dried tomatoes and/or spaghetti sauce have even more bioavailability of this nutrient. Lycopene may reduce risk of gastrointestinal and prostate cancer (Clinton, 1998).
Carotenoids. Carotenoids are a class of pigmented molecules that are found in carrots and apricots. One type of carotenoid, lutein, promotes healthy eyes. People who consume high levels of lutein have a lower risk of macular degeneration and cataracts (Getz, 2000). Lutein and its related carotenoid called zeaxanthin may also improve cognitive abilities during aging.
Vitamin C. Vitamin C is one of the antioxidant vitamins. It is found in high amounts in bell peppers, broccoli, and citrus fruits. Vitamin C promotes adrenal gland functioning, immune system health, and repair of damaged tissues (Getz, 2000).
Vitamin E. Nuts, such as almonds, walnuts, and hazelnuts are excellent sources of vitamin E. This vitamin is also found in wheat germ and sunflower oil. A diet high in vitamin E has been associated with lower risk of heart disease (Getz, 2000).
Making Dietary Choices to Maximize Antioxidant Consumption
Fruits and vegetables remain some of the best sources of antioxidants. For example, blueberries, raspberries, and blackberries are compounds with antioxidant properties. The best approach to ensure you get enough is to eat a wide range of fruits and vegetables each day.
Aim to eat at least five servings of fruits and vegetables daily to ensure you get enough antioxidant compounds in your diet. The color of the foods you eat can provide a clue as to which antioxidants you receive. For example, foods rich in carotenoids are often orange or yellow in color. Resveratrol-rich foods are deep red or purple. Thus, a good strategy is to eat fruits and vegetables across the color spectrum. Consider foods that are red-purple (grapes, berries), blue (plums, blueberries), light green (onions, asparagus, cabbage, Brussels sprouts), deep green (leafy green vegetables), yellow-orange (lemons, papayas, peaches), orange (pumpkins, carrots), and red (tomatoes, guava).
Eating fresh foods ensures that you get a maximum amount of dietary antioxidants. Dried fruits also provide an antioxidant boost. One of the other benefits of eating fresh fruits and vegetables, rather than supplements, is that they often contain complementary nutrients that increase bioavailability of antioxidants. For example, eating leafy greens contain plenty of iron that helps your intestines absorb more vitamin C. Keep in mind that snack foods such as nuts and seeds provide another healthy way to get antioxidant vitamins such as vitamin E.
Dosage and Safe Limits of Antioxidant Consumption
Scientists are actively studying the properties of antioxidants to determine appropriate dosages. High doses of supplemental antioxidants may pose certain risks, so it may be best to get antioxidants from food as part of your regular diet.