Plants contain a remarkable number of molecules called phytochemicals. Their primary purpose is to participate in the plant's metabolic processes, but they may also benefit human health when they are part of our diet. Among these phytochemicals are compounds called carotenoids. Scientists believe that among several functions, carotenoids behave like antioxidants, protecting the body from the harmful effects of oxygen that can contribute to degenerative disease.
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Antioxidants are chemicals that naturally react with molecules called free radicals. Free radicals have extra electrons around them that can bombard the molecules of cell membranes and lead to cell damage. Antioxidants take up these extra electrons so that your cells don't have to. Free radicals may come from environmental contaminants, but they also form as a result of normal bodily processes.
Types and Sources
Although there are 600 different types of carotenoids found in nature, the most commonly studied are beta carotene, lutein, zeaxanthin, canthaxanthin, beta cryptoxanthan and lycopene. They are responsible for the yellow, orange and red pigments in many fruits and vegetables but are also present in large quantities in leafy greens such as spinach, kale and collard greens. Carrots, squash and tomatoes are also examples of foods that contain carotenoids. Because some carotenoids, like beta carotene, can be converted into the fat-soluble vitamin A, carotenoids are best absorbed when fat is eaten along with a carotenoid-rich meal.
Antioxidant Health Effects
According to a 2013 article in "Advances in Nutrition," current knowledge suggests that carotenoids like beta carotene are important for the health of the eyes. They are sometimes prescribed as supplements to reduce risk of development of an eye disease called macular degeneration. Also, high dietary levels of carotenoids are linked with an overall decrease in mortality, possibly due to reduced cancer risk. Carotenoids accomplish these feats by behaving as antioxidants and mitigating the cellular damage that leads to degenerative disease.
An interesting, non-antioxidant property of carotenoids such as lutein and zeaxanthin is that they absorb certain wavelengths of light. This action protects the muscles of the eye from light damage. As a result, glare disability is reduced and contrast and vision distance are improved. It has also been shown to be effective against light sensitivity in people who have erythropoietic protoporphyria, a blood disease that makes a person break out in a rash when exposed to the sun.
Beta Carotene Supplements
Eating the recommended five servings per day of fruits and vegetables provides between 6 and 8 milligrams of beta carotene, according to MedlinePlus. MedlinePlus also recommends that carotenoids come from the diet rather than from a supplement unless otherwise directed by a doctor for a specific purpose, and states that high-dose carotenoids like beta carotene may actually be harmful. As always, it is important to discuss the introduction of any new supplement with your doctor.