There are two types of vitamin A that are found in the diet: Preformed vitamin A (retinol and its esterified form, retinyl ester) : found in animal … Vitamin A is available in multivitamins and as a stand-alone supplement, often in the form of retinyl acetate or retinyl palmitate [2]. Retinal plays an important role in vision. In a more detailed analysis of results, supplementation with lutein and zeaxanthin reduced the risk of advanced AMD by 26% in participants with the lowest dietary intakes of these two carotenoids who took a supplement containing them compared to those who did not take a supplement with these carotenoids [33]. About half of all measles deaths happen in Africa, but the disease is not limited to low-income countries. Preterm infants with vitamin A deficiency have an increased risk of eye, chronic lung, and gastrointestinal diseases [17]. The evidence on the relationship between beta-carotene and prostate cancer is mixed. Certain groups such as premature infants, people with cystic fibrosis and pregnant or breastfeeding women in developing countries are more at risk of vitamin A deficiency (23). Vitamin A, also known as retinol, has several important functions. A plasma retinol concentration lower than 0.70 micromoles/L (or 20 micrograms [mcg]/dL) reflects vitamin A inadequacy in a population, and concentrations of 0.70–1.05 micromoles/L could be marginal in some people [5]. However, it’s important not to exceed the tolerable upper limit (UL) of 10,000 IU (3,000 mcg) for adults to prevent toxicity (27). In: Coates PM, Betz JM, Blackman MR, et al., eds. about your interest in, questions about, or use of dietary supplements and what may be best for your overall health. Learn about different causes. One mcg RAE is equivalent to 1 mcg retinol, 2 mcg supplemental beta-carotene, 12 mcg dietary beta-carotene, or 24 mcg dietary alpha-carotene or beta-cryptoxanthin [5]. Pediatr Clin North Am 2009;56:1123-41. Pregnant women and … Function. According to an analysis of data from the 2007–2008 National Health and Nutrition Examination Survey (NHANES), the average daily dietary vitamin A intake in Americans aged 2 years and older is 607 mcg RAE [13]. The CARET study ended early, after the investigators found that daily beta-carotene (30 mg) and retinyl palmitate (7,500 mcg RAE [25,000 IU]) supplements increased the risk of lung cancer and cardiovascular disease mortality [41]. Oxidative stress has been linked to various chronic illnesses like diabetes, cancer, heart disease and cognitive decline (10). Am J Clin Nutr 2011;94:658S-65S. However, vitamin A deficiency is common in many developing countries, often because residents have limited access to foods containing preformed vitamin A from animal-based food sources and they do not commonly consume available foods containing beta-carotene due to poverty [2]. © 2005-2021 Healthline Media a Red Ventures Company. The Physicians' Health Study did not find an increased lung cancer risk in participants taking beta-carotene supplements, possibly because only 11% of physicians in the study were current or former smokers. The body needs vitamin A to maintain the corneas and other epithelial surfaces, so the lower serum concentrations of vitamin A associated with measles, especially in people with protein-calorie malnutrition, can lead to blindness. Vitamin E is an antioxidant, which protects body cells from damage. In: Bowman B, Russell R, eds. Vitamin A is a fat-soluble nutrient that plays a vital role in your body. The foods from animal sources in Table 2 contain primarily preformed vitamin A, the plant-based foods have provitamin A, and the foods with a mixture of ingredients from animals and plants contain both preformed vitamin A and provitamin A. The B complex vitamins function as enzyme cofactors (coenzymes) or … Tanumihardjo SA. Objective: Vitamin A and its retinoid derivates play an important role in regulation of normal growth and development. In these countries, low vitamin A intake is most strongly associated with health consequences during periods of high nutritional demand, such as during infancy, childhood, pregnancy, and lactation. We encourage you to talk to your healthcare providers (doctor, registered dietitian, pharmacist, etc.) Although vitamin A's chief function involves the eyes and vision, it also plays important roles in the development of bones, including the teeth. The FNB has not established ULs for beta-carotene and other provitamin A carotenoids [25]. GlaxoSmithKline. J Pediatr Gastroenterol Nutr 2002;35:246-59. Vitamin A is vital for growth and development, cell recognition, vision, immune function, and reproduction and helps the heart, lungs, and kidneys. This condition can be reversed by discontinuing beta-carotene ingestion. In: Coates PM, Betz JM, Blackman MR, et al., eds. [, The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study Group. These include: helping your body's natural defence against illness and infection (the immune system) work properly; helping vision in dim light; keeping skin and the lining of some parts of the body, such as the nose, healthy; The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system, and for good vision. Antioxidants are substances that might protect your cells against the effects of free radicals — molecules produced when your body breaks down food or is exposed to tobacco smoke and radiation. Several studies have shown that oral supplementation can correct low serum beta-carotene levels in people with cystic fibrosis, but no controlled studies have examined the effects of vitamin A supplementation on clinical outcomes in patients with cystic fibrosis [22-24]. Adequate Intake (AI): Intake at this level is assumed to ensure nutritional adequacy; established when evidence is insufficient to develop an RDA. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. Vitamin A supplementation for cystic fibrosis. In developed countries, the amounts of vitamin A in breast milk are sufficient to meet infants' needs for the first 6 months of life. Protects Your Eyes From Night Blindness and Age-Related Decline. The risk of advanced AMD was also 18% lower in participants who took the modified AREDS supplement containing lutein and zeaxanthin but not beta-carotene than in participants who took the formulation with beta-carotene but not lutein or zeaxanthin. Food Labeling: Revision of the Nutrition and Supplement Facts Labels. Frank vitamin A deficiency is rare in the United States. In the eyes, retinal is combined with a protein called opsin to give rhodopsin, an essential light absorbing molecule needed for color vision and seeing in dim light. Women who might be pregnant should not take high doses of vitamin A supplements [2]. They promote healthy muscle, nerve, brain, and heart function, as well as healthy skin, hair, and eyes; and can also aid in the prevention of certain types of anemia. Alli: Potential for Misuse and Drug Interactions. Vitamin A helps the skin grow and also improves skin repair. Functions and Benefits of Vitamin A Vitamin A has many different roles within the body, and it plays a key role in vision and healthy growth. [. Cancer Res 2009;69:3833-41. Vitamin A (retinol, retinoic acid) is a nutrient important to vision, growth, cell division, reproduction and immunity. Vitamin A (and its precursor*, beta-carotene) *A precursor is converted by the body to the vitamin. Both retinyl esters and provitamin A carotenoids are converted to retinol, which is oxidized to retinal and then to retinoic acid [2]. Vitamin A exists as a provitamin in vegetables (i.e., b-carotene). People with vitamin A deficiency (and, often, xerophthalmia with its characteristic Bitot's spots) tend to have low iron status, which can lead to anemia [3,14]. Though vitamin A deficiency is rare in developed countries like the US, it’s common in developing countries, as these populations may have limited access to food sources of preformed vitamin A and provitamin A carotenoids. Vitamin A impacts immune health by stimulating responses that protect your body from illnesses and infections. Share on Pinterest. Other effects of vitamin A deficiency in pregnant and lactating women include increased maternal and infant morbidity and mortality, increased anemia risk, and slower infant growth and development. [. J Nutr 2011;141:261-6. AMD's etiology is usually unknown, but the cumulative effect of oxidative stress is postulated to play a role. Vitamin A. [, van den Broek N, Dou L, Othman M, Neilson JP, Gates S, Gulmezoglu AM. The FNB has established ULs for preformed vitamin A that apply to both food and supplement intakes [5]. Table 2 suggests many dietary sources of vitamin A. Retinoic acid plays an important role in reproductive biology, bone remodeling, and epithelial tissue homeostasis. [, Rodahl K, Moore T. The vitamin A content and toxicity of bear and seal liver. [, Foster A, Sommer A. Corneal ulceration, measles, and childhood blindness in Tanzania. Multivitamin supplements typically contain 750–3,000 mcg RAE (2,500–10,000 IU) vitamin A, often in the form of both retinol and beta-carotene. Modern Nutrition in Health and Disease. [, Age-Related Eye Disease Study Research Group. Examples include the psoriasis treatment acitretin (Soriatane®) and bexarotene (Targretin®), used to treat the skin effects of T-cell lymphoma. Int J Epidemiol 2010;39 Suppl 1:i48-55. Vitamin A is used to treat vitamin A deficiency . The vitamin A doses used in these studies are much higher than the UL. But in women with vitamin A deficiency, breast milk volume and vitamin A content are suboptimal and not sufficient to maintain adequate vitamin A stores in infants who are exclusively breastfed [19]. Because vitamin A is fat soluble, it’s stored in body tissue for later use. When appropriate, retinyl esters are hydrolyzed to generate all-trans-retinol, which binds to retinol binding protein (RBP) before being released in the bloodstream. 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