There are some 563 identified carotenoids. Carotenoids are the red, yellow and orange pigments in plants. The most frequently consumed carotenoids in the America diet are beta-carotene, lycopene, lutein, alpha-carotene, beta-cryptoxanthin, and zeaxanthin. Plants and algae, as well as photosynthetic bacteria, synthesize these pigments.
Provitamin A Carotenoids
Vitamin A that is found in colorful fruits and vegetables is called provitamin A carotenoid. Your body needs vitamin A for normal vision, growth and development and immune system function. Alpha- and beta-carotene and beta-cryptoxanthin are provitamin A carotenoids. About 34 percent of vitamin A consumed by women and 26 percent of vitamin A consumed by men in the United States comes from provitamin A carotenoids, according to the U.S. Office of Dietary Supplements, or ODS. Some provitamin A carotenoids appear to have antioxidant action. However, this has not been consistently demonstrated in people, according to the ODS. Antioxidants may help reduce your risk for chronic diseases because they protect your cells from free radicals, potentially damaging byproducts that come from oxygen metabolism in your body.
Other Carotenoids
Lycopene, lutein and zeaxanthin do not have vitamin A activity. However, they have other health-promoting properties, so the Institute of Medicine recommends including fruits and veggies rich in such carotenoids to your diet. For example, high intakes of lycopene from tomatoes may help reduce risk for prostate cancer, according to the Linus Pauling Institute. Also, zeaxanthin and leutin are the only carotenoids found in your eye's lens and retina. A study published in the December 2004 issue of the "Journal of Nutrition" indicates that a diet high in lutein and zeaxanthin may reduce your risk for age-related cataracts. These carotenoids also may slow the development of macular degeneration related to age, according to the Linus Pauling Institute; however, more research is needed to determine if supplemental carotenoids have similar effects to dietary carotenoids when it comes to reducing the risk for health conditions.
Classification
Carotenoids are broadly divided into two classes: The first is carotenes including alpha- and beta-carotene and lycopene. These give the red and orange color to fruits and veggies. The second is xanthophylls including lutein, beta-cryptoxanthin and zeaxanthin. These are the yellow pigments.
Considerations
No matter which class you are consuming, you must have at least 3 to 5 g of fat in your meal for your body to absorb carotenoids effectively. Among the provitamin A carotenoids, beta-carotene is the one most efficiently converted into vitamin A by your body. Others, such as beta-cryptoxanthin and alpha-carotene, are only converted to vitamin A half as efficiently, according to ODS.
References
- Linus Pauling Institute; Carotenoids; Jane Higdon, Ph.D.; June 2009
- Office of Dietary Supplements: Vitamin A and Carotenoids
- "Journal of Separation Science"; Highly Sensitive and Accurate Profiling of Carotenoids by Supercritical Fluid Chromatography Coupled with Mass Spectrometry; A. Matsubara, et al.; 2009
- "Guide to Nutritional Supplements"; Benjamin Caballero; 2009
- "Journal of Nutrition"; Xanthophylls and Alpha-Tocopherol Decrease UVB-Induced Lipid Peroxidation and Stress Signaling in Human Lens Epithelial Cells; C. Chitchumroonchokchai, et al.; Dec. 2004
- "New Zealand Journal of Agricultural Research"; Egg Yolk Pigmenting Properties; D.C. Johns; 1986
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