What can foods rich in lutein and zeaxanthin do for you?
What are lutein and zeaxanthin?Lutein and zeaxanthin are two of the most abundant carotenoids in the North American diet. Unlike beta-carotene, alpha-carotene and beta-cryptoxanthin, these two carotenoids are not considered to be "provitamin A" compounds, as they are not converted in the body into retinol, an active form of vitamin A. The names of both of these yellow colored phytonutrients reflect their natural hue with lutein being derived from the Latin word luteus meaning golden yellow while zea refers to the corn genus and xantho- is derived from a Greek word that means yellow. While these carotenoids both have yellow pigments, they are found concentrated in foods of others colors, notably leafy green vegetables, since these foods also feature a host of other phytonutrients pigments in addition to lutein and zeaxanthin.
Antioxidant ActivityIn recent years, carotenoids have received a tremendous amount of attention as potential anti-cancer and anti-aging compounds. Carotenoids are powerful antioxidants, protecting the cells of the body from damage caused by free radicals. Carotenoids, and specifically beta-carotene, are also believed to enhance the function of the immune system. Promote Eye HealthThe eyes are repositories for carotenoids with lutein and zeaxanthin concentrated in the retina and lens. Observational studies have noted that higher dietary intake of lutein and zeaxanthin is related to reduced risk of cataracts and age-related macular degeneration, two eye conditions for which there is minimal options when it comes to effective prevention. Researchers speculate that these carotenoids may promote eye health through their ability to protect the eyes from light-induced oxidative damage and aging through both their antioxidant actions as well as their ability to filter out UV light.
A low dietary intake of carotenoids such as lutein and zeaxanthin is not known to directly cause any diseases or health conditions, at least in the short term although long-term inadequate intake of carotenoids is associated with chronic disease, including heart disease and various cancers. One important mechanism for this carotenoid-disease relationship appears to be free radicals. Research indicates that diets low in carotenoids can increase the body's susceptibility to damage from free radicals. As a result, over the long term, carotenoid-deficient diets may increase tissue damage from free radical activity, and increase risk of chronic diseases like heart disease and cancers.
High intake of carotenoid-containing foods or supplements is not associated with any toxic side effects. As a result, the Institute of Medicine at the National Academy of Sciences did not establish a Tolerable Upper Intake Level (UL) for carotenoids when it reviewed these compounds in 2000.
Lutein appears to be sensitive to cooking and storage. Prolonged cooking of green, leafy vegetables is suggested to reduce their lutein content. The concentration of lutein found in roasted barley that has been water extracted was shown to decrease as roasting temperature increased. Additionally, the lutein content of wheat seeds has been found to decline with longer storage times. There is minimal research specifically focusing upon the effects of cooking, storage or processing upon zeaxanthin.
Carotenoids such as lutein and zeaxanthin are fat-soluble substances, and as such require the presence of dietary fat for proper absorption through the digestive tract. Consequently, your carotenoid status may be impaired by a diet that is extremely low in fat or if you have a medical condition that causes a reduction in the ability to absorb dietary fat such as pancreatic enzyme deficiency, Crohn's disease, celiac sprue, cystic fibrosis, surgical removal of part or all of the stomach, gall bladder disease, and liver disease. Due to low consumption of fruits and vegetables, many adolescents and young adults do not take in enough carotenoids such as lutein and zeaxanthin. In addition, if you smoke cigarettes and/or drink alcohol, you may have lower than normal blood levels of carotenoids. Statistically speaking, smokers and drinkers eat fewer foods that contain lutein and zeaxanthin. Also, researchers suspect that cigarette smoke destroys carotenoids. However, if you do smoke or drink, use carotenoid supplements with caution
The cholesterol-lowering medications referred to as bile acid sequestrants (Cholestyramine, Colestipol, and Colestid) lower blood levels of carotenoids. In addition, margarines enriched with plant sterols such as Benecol and Take Control, may decrease the absorption of carotenoids. Olestra, a fat substitute added to snack foods, may also decrease the absorption of carotenoids.
Lutein and zeaxanthin are oftentimes found together in dietary supplements. A common source for deriving these carotenoids for supplements is from marigold flowers. If you have a corn allergy, check the supplement label carefully as some products have a corn oil base.
To date, no recommended dietary intake levels have been established for lutein, zeaxanthin and carotenoids. In an effort to set such recommendations, the Institute of Medicine at the National Academy of Sciences reviewed the existing scientific research on carotenoids in 2000. Despite the large body of population-based research that links high consumption of foods containing beta-carotene and other carotenoids with a reduced risk of several chronic diseases, the Institute of Medicine concluded that this evidence was not strong enough to support a required carotenoid intake level because it is not yet known if the health benefits associated with carotenoid-containing foods are due to the carotenoids or to some other substance in the food. However, the National Academy of Sciences supports the recommendations of various health agencies, which encourage individuals to consume five or more servings of fruits and vegetable every day.