Eating your carotenoids is as easy as eating your carrots -- or any other colorful vegetable or fruit. Carotenoids are orange, red, green or yellow pigments that give vegetables and fruits their deep color, but they're more than just a pretty addition to the garden. Some carotenoids act as antioxidants, substances that keep cells healthy by scavenging and destroying potentially harmful molecules known as free radicals. Plants, algae and certain types of bacteria all produce the more than 600 carotenoids found in nature.
Types
Carotenoids fall into two general classes: carotenes and xanthophylls. In American diets, alpha-carotene, found in pumpkin, carrots and other vegetables, and beta-carotene, found in carrots, pumpkin, spinach, sweet potato and greens, are some of the most common carotenes. Lycopene, found in tomatoes and watermelon, is another frequently consumed carotene in the American diet. Beta-cryptoxanthin, found in pumpkins, red peppers and papaya, and lutein and zeaxanthin, found in greens as well as squash, peas, Brussels sprouts, broccoli and corn, are the most commonly consumed xanthophylls.
Actions
Alpha-carotene, beta-carotene and beta-cryptoxanthin are called provitamin A carotenes because they are converted to retinol, the active form of vitamin A, after being consumed. Beta-carotene converts to vitamin A twice as efficiently as alpha-carotene and beta-cryptoxanthin. Lutein, lycopene, and zeaxanthin do not convert to retinol. All act as antioxidants and may help prevent heart disease along with cancers. In the eye, lutein and xanthophyll filter harmful blue light that can damage the lens and retina; they may reduce the risk of cataracts as well as age-related macular degeneration.
Supplements Risks
Not all studies have shown a benefit from taking carotenoid supplements; some studies have actually shown harm. A meta-analysis of four previous studies conducted by researchers from the Lee Moffitt Cancer Center and Research Institute at the University of Florida published in the July 2008 issue of "Cancer" found that beta-carotene supplementation, particularly in high doses of up to 3 mg per day, increased the risk of developing lung cancer in smokers.
Considerations
In general, getting carotenoids and other nutrients from foods is preferable to taking them in supplements. Cooking appears to enhance the benefits of many carotenoids, such as carrots, tomatoes and corn, especially when they're cooked in healthy oils such as olive oil or other monounsaturated fats. Fats increase the absorption of carotenoids; consuming 3 to 5 g of fat with carotenoids is enough to aid absorption, the Linus Pauling Institute reports. Cutting or chopping foods containing carotenoids also increases their bioavailability.
References
- Linus Pauling Institute; Carotenoids; Jane Higdon, Ph.D.; December 2005
- Office of Dietary Supplements: Vitamin A and Carotenoids
- University of Maryland Medical Center; Vitamins-Carotenoids; Harvey Simon, M.D.; February 2009
- "Cancer;" Beta-Carotene in Multivitamins and the Possible Risk of Lung Cancer Among Smokers Versus Former Smokers; T. Tanvetyanon, et al.; July 2008
Member Comments