Institute of Medicine. Vitamin A also has antioxidant properties. In the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study, 29,133 male smokers took 50 mg/day alpha-tocopherol, 20 mg/day beta-carotene, 50 mg/day alpha-tocopherol and 20 mg/day beta-carotene, or placebo for 5–8 years . If so, supplements containing carotenoids with antioxidant functions, such as beta-carotene, lutein, and zeaxanthin, might be useful for preventing or treating this condition. CARET study participants who took daily supplements of beta-carotene and retinyl palmitate had a 35% lower risk of nonaggressive prostate cancer than men not taking the supplements . One of the early signs of xerophthalmia is night blindness, or the inability to see in low light or darkness [2,16]. There are many dietary sources of both preformed vitamin A and provitamin A carotenoids. JAMA 2013;309:2005-15. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. Function. Preterm infants with vitamin A deficiency have an increased risk of eye, chronic lung, and gastrointestinal diseases . Lack of effect of long-term supplementation with beta carotene on the incidence of malignant neoplasms and cardiovascular disease. [, Hennekens CH, Buring JE, Manson JE, Stampfer M, Rosner B, Cook NR, et al. 10th ed. It also helps protect and maintain the cornea — the outermost layer of your eye — and the conjunctiva — a thin membrane that covers the surface of your eye and inside of your eyelids (6). The amounts of vitamin A in stand-alone supplements range widely . In: Coates PM, Betz JM, Blackman MR, et al., eds. The Journal of Nutrition 2010;140:2268S-85S. And even large supplemental doses (20–30 mg/day) of beta-carotene or diets with high levels of carotenoid-rich food for long periods are not associated with toxicity. The beta-carotene and retinol efficacy trial: incidence of lung cancer and cardiovascular disease mortality during 6-year follow-up after stopping β-carotene and retinol supplements. The first type, preformed vitamin A, is found in meat, poultry, fish, and dairy products. Carotenoids fight free radicals — highly reactive molecules that can harm your body by creating oxidative stress (9). Furthermore, girls and African-American children have a higher risk of consuming less than two-thirds of the vitamin A RDA than other children . There are two forms of vitamin A found in food. The symptoms of hypervitaminosis A following sudden, massive intakes of vitamin A, as with Arctic explorers who ate polar bear liver, are acute . This section focuses on three diseases and disorders in which vitamin A might play a role: cancer, age-related macular degeneration (AMD), and measles. The FNB has established ULs for preformed vitamin A that apply to both food and supplement intakes . Your body’s ability to effectively convert carotenoids, such as beta-carotene, into active vitamin A depends on many factors — including genetics, diet, overall health and medications (24). 1 IU supplemental beta-carotene = 0.3 mcg RAE, 1 IU dietary beta-carotene = 0.05 mcg RAE, 1 IU dietary alpha-carotene or beta-cryptoxanthin = 0.025 mcg RAE. Vitamin A (and its precursor*, beta-carotene) *A precursor is converted by the body to the vitamin. Alli: Potential for Misuse and Drug Interactions. These values, which vary by age and gender, include: RDAs for vitamin A are given as retinol activity equivalents (RAE) to account for the different bioactivities of retinol and provitamin A carotenoids, all of which are converted by the body into retinol (see Table 1). It protects your eyes from age-related issues in vision and night blindness [, Mondul AM, Watters JL, Mannisto S, Weinstein SJ, Snyder K, Virtamo J, et al. Vitamin B6 is also called pyridoxine. Other carotenoids found in food, such as lycopene, lutein, and zeaxanthin, are not converted into vitamin A. The prevalence of vitamin A deficiency in developing countries begins to increase in young children just after they stop breastfeeding . Most dietary provitamin A comes from leafy green vegetables, orange and yellow vegetables, tomato products, fruits, and some vegetable oils . Retinoic acid plays an important role in reproductive biology, bone remodeling, and epithelial tissue homeostasis. Oxidative stress has been linked to various chronic illnesses like diabetes, cancer, heart disease and cognitive decline (10). Vitamin A and its derivatives, the retinoids, have a profound influence on organ development, cell proliferation, and cell differentiation and their deficiency originates or predisposes a number of disabilities (McDowell, 2000; Esteban-Pretel et al., 2010). Am J Clin Nutr 2006;84:174-82. Vitamin A supplementation for cystic fibrosis. 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 . The relevance of these results to people who have never smoked or to the effects of beta-carotene or retinol from food or multivitamins (which typically have modest amounts of beta-carotene) is not known. [, Graham-Maar RC, Schall JI, Stettler N, Zemel BS, Stallings VA. Elevated vitamin A intake and serum retinol in preadolescent children with cystic fibrosis. 1) Vitamin A Enhances Immune Response Importantly, the study revealed that beta-carotene was not a required ingredient; the original AREDS formulation without beta-carotene provided the same protective effect against developing advanced AMD. [, van den Broek N, Dou L, Othman M, Neilson JP, Gates S, Gulmezoglu AM. Vitamin A impacts immune health by stimulating responses that protect your body from illnesses and infections. Vitamin A is needed for eye health, vision, immune function, cell growth, reproduction and fetal development. Vitamin C (ascorbic acid) is a strong antioxidant known for strengthening the immune system by fighting off colds and other infectious diseases. Dietary supplement use and prostate cancer risk in the Carotene and Retinol Efficacy Trial. Vitamin A: is it a risk factor for osteoporosis and bone fracture? 9th ed. Although vitamin A's chief function involves the eyes and vision, it also plays important roles in the development of bones, including the teeth. Int J Epidemiol 2010;39 Suppl 1:i48-55. For a reader-friendly overview of Vitamin A, see our consumer fact sheet on Vitamin A. Vitamin A is the name of a group of fat-soluble retinoids, including retinol, retinal, and retinyl esters [1-3]. Vitamin A as retinyl esters in chylomicrons was also found to have a… ... Foods in nutrient-dense forms contain essential vitamins and minerals and also dietary fiber and other naturally occurring substances that may have positive health effects. Though it’s possible to consume excessive preformed vitamin A through animal-based sources like liver, toxicity is most commonly linked to excessive supplement intake and treatment with certain medications, such as Isotretinoin (28, 29). Vitamin A supplementation during pregnancy for maternal and newborn outcomes. Vitamin A is important for normal vision, the immune system, and reproduction. When appropriate, retinyl esters are hydrolyzed to generate all-trans-retinol, which binds to retinol binding protein (RBP) before being released in the bloodstream. Function. There are two different types of vitamin A. Objective: Vitamin A and its retinoid derivates play an important role in regulation of normal growth and development. To convert IU to mcg RAE, use the following : RAE can only be directly converted into IUs if the source or sources of vitamin A are known. The active constituents of Vitamin A consist preformed Vitamin A or retinoids like retinol, retinal, retinoic acid and provitamin A carotenoids like β-carotene, alpha-carotene, gamma-carotene and xanthophyll beta-cryptoxanthin. AMD's etiology is usually unknown, but the cumulative effect of oxidative stress is postulated to play a role. 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. This vitamin also plays an important role in the proteins … Vitamin A is listed on the new Nutrition Facts and Supplement Facts labels in mcg RAE . It plays a critical role in maintaining vision, neurological function, healthy skin and more. FDA developed DVs to help consumers compare the nutrient contents of foods and dietary supplements within the context of a total diet. A few examples are provided below. Vitamin A is key for good vision, a healthy immune system, and cell growth. Vitamin A deficiency also increases the severity and mortality risk of infections (particularly diarrhea and measles) even before the onset of xerophthalmia [5,14,16]. In all three of these studies, taking very high doses of beta-carotene, with or without 7,500 mcg RAE (25,000 IU) retinyl palmitate or 325 mg aspirin, did not prevent lung cancer. Vitamin A also helps the heart, lungs, kidneys, and other organs work properly. Vitamin A (and its precursor*, beta-carotene) *A precursor is converted … The manufacturers of Alli and Xenical recommend encouraging patients on orlistat to take a multivitamin supplement containing vitamin A and beta-carotene, as well as other fat-soluble vitamins [43,44]. However, the ATBC study found that baseline serum beta-carotene and retinol levels and supplemental beta-carotene had no effect on survival . Retinol and carotenoid levels are typically measured in plasma, and plasma retinol levels are useful for assessing vitamin A inadequacy. 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 . Biochem J 1943;37:166-8. Supplementation with beta-carotene, with or without retinyl palmitate, for 5–8 years has been associated with an increased risk of lung cancer and cardiovascular disease in current and former male and female smokers and in male current and former smokers occupationally exposed to asbestos [27,41]. Bailey RL, Gahche JJ, Lentino CV, Dwyer JT, Engel JS, Thomas PR, et al. Vitamin A is possibly effective in preventing cataracts, or slowing the progression of retinitis pigmentosa (an eye disease that causes damage to the retina). Vitamin A, also known as retinol, has several important functions. However, many dietary supplements (such as multivitamins) do not provide all of their vitamin A as retinol or its ester forms. To use them, your body must convert both forms of vitamin A to retinal and retinoic acid, the active forms of the vitamin. Vitamin A in the form of retinoic acid is essential for gene transcription. Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. Cochrane Database Syst Rev 2010:CD008666. In fact, both the CARET and ATBC studies showed a significant increase in lung cancer risk among study participants taking beta-carotene supplements or beta-carotene and retinyl palmitate supplements. We encourage you to talk to your healthcare providers (doctor, registered dietitian, pharmacist, etc.) Both provitamin A and preformed vitamin A must be metabolized intracellularly to retinal and retinoic acid, the active forms of vitamin A, to support the vitamin's important biological functions [2,3]. The causes of acid reflux in infants are numerous and may not be anything to worry about. The most significant effect of long-term, excess beta-carotene is carotenodermia, a harmless condition in which the skin becomes yellow-orange [1,25]. 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]. Retinol is taken up by the cell where it is oxidized to retinaldehyde (by retinol dehydrogenases), which is then oxidized to give retinoic acid. The FNB has not established ULs for beta-carotene and other provitamin A carotenoids . Improves Skin and Hair. Perhaps one of the best-known functions of vitamin A is its role in vision and eye health. The evidence on the relationship between beta-carotene and prostate cancer is mixed. Michel SH, Maqbool A, Hanna MD, Mascarenhas M. Nutrition management of pediatric patients who have cystic fibrosis. In some studies, high plasma or serum concentrations of some provitamin A carotenoids have been associated with a lower risk of various health outcomes, but these studies have not definitively demonstrated that this relationship is causal. Arch Ophthalmol 2001;119:1417-36. In developing countries, vitamin A deficiency typically begins during infancy, when infants do not receive adequate supplies of colostrum or breast milk . For this reason, those who follow plant-based diets — especially vegans — should be vigilant about getting enough carotenoid-rich foods. For clinical practice purposes, plasma retinol levels alone are sufficient for documenting significant deficiency. Vitamin A is a fat-soluble vitamin that is absorbed with fats in your diet and stored in your body's fatty tissue. The conversion of retinal to retinoic acid is irreversible and the process is therefore tightly regulated because retinoic acid functions as a ligand for nuclear receptors. Vitamin A helps form and maintain healthy teeth, bones, soft tissue, mucous membranes, and skin. The FNB based these ULs on the amounts associated with an increased risk of liver abnormalities in men and women, teratogenic effects, and a range of toxic effects in infants and children. Get the latest public health information from CDC: https://www.coronavirus.gov Acid reflux in infants can be treated with changes in feeding, burping, and sleeping position, or in some cases, medication or surgery. Preformed vitamin A is found in foods from animal sources, including dairy products, fish, and meat (especially liver). 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]. Ross A. Vitamin A and Carotenoids. Since vitamin A is fat-soluble, it’s stored in your body and can reach unhealthy levels over time. 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 . Both deficiency and surplus intake may cause severe side effects, so while it’s crucial to meet the RDA of 700–900 mcg daily for adults, don’t exceed the upper daily limit of 3,000 mcg. The most common and readily recognized symptom of vitamin A deficiency in infants and children is xerophthalmia. The vitamin A doses used in these studies are much higher than the UL. It exists naturally in the foods you eat and can also be consumed through supplements. Vitamin A can interact with certain medications, and some medications can have an adverse effect on vitamin A levels. Vitamin A is used to treat vitamin A deficiency . The top food sources of vitamin A in the U.S. diet include dairy products, liver, fish, and fortified cereals; the top sources of provitamin A include carrots, broccoli, cantaloupe, and squash [4,5]. Converting Units of Measure for Folate, Niacin, and Vitamins A, D, and E on the Nutrition and Supplement Facts Labels: Guidance for Industry. Even with a mild vitamin A deficiency in pregnant rats, there was reduction of nephrons in the … It then enters your bloodstream, at which point your body can use it (4). In addition, vitamin A aids immune function and helps provide a barrier against infections of the skin, lungs and mouth. BMJ 2011;343:d5094. Function Vitamin A helps form and maintain healthy teeth, skeletal and soft tissue, mucus membranes, and skin. Updated: February 14, 2020 History of changes to this fact sheet, U.S. Department of Health & Human Services, Strengthening Knowledge and Understanding of Dietary Supplements, My Dietary Supplement and Medicine Record, How To Evaluate Health Information on the Internet, NIH Consortium for Advancing Research on Botanical and Other Natural Products (CARBON) Program, Analytical Methods and Reference Materials (AMRM), Dietary Supplement Ingredient Database (DSID), Computer Access to Research on Dietary Supplements (CARDS) Database, Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Vitamin A is critical for vision as an essential component of rhodopsin, a protein that absorbs light in the retinal receptors, and because it supports the normal differentiation and functioning of the conjunctival membranes and cornea [2-4]. Functions A. Vitamin A. Vitamin A is necessary for support of growth, health and life of major animal species. Encyclopedia of Dietary Supplements. In some cases, fortified foods and dietary supplements may be useful in providing one or more nutrients that otherwise may be consumed in less-than-recommended amounts.". It is found in dark green vegetables, whole milk, meats, liver, fish, egg yolk and butter. [, Foster A, Sommer A. Corneal ulceration, measles, and childhood blindness in Tanzania. Includes a variety of protein foods, including seafood, lean meats and poultry, eggs, legumes (beans and peas), nuts, seeds, and soy products. Two forms of vitamin A are available in the human diet: preformed vitamin A (retinol and its esterified form, retinyl ester) and provitamin A carotenoids [1-5]. Vitamins have diverse biochemical functions. Retinal plays an important role in vision. [, Ribaya-Mercado JD, Blumberg JB. Adequate dietary intake of vitamin A helps protect against certain eye diseases, such as age-related macular degeneration (AMD). Vitamin A (retinol, retinoic acid) is a nutrient important to vision, growth, cell division, reproduction and immunity. Vitamin A also supports cell growth and differentiation, playing a critical role in the normal formation and maintenance of the heart, lungs, kidneys, and other organs . Beta-Carotene. Cochrane Database Syst Rev 2010:CD006751.pub2. Routine vitamin A supplementation for the prevention of blindness due to measles infection in children. *Adequate Intake (AI), equivalent to the mean intake of vitamin A in healthy, breastfed infants. 2nd ed. Vitamin A compounds are essential fat-soluble molecules predominantly stored in the liver in the form of retinyl esters (e.g., retinyl palmitate). Estimated Average Requirement (EAR): Average daily level of intake estimated to meet the requirements of 50% of healthy individuals; usually used to assess the nutrient intakes of groups of people and to plan nutritionally adequate diets for them; can also be used to assess the nutrient intakes of individuals. The federal government's 2015-2020 Dietary Guidelines for Americans notes that "Nutritional needs should be met primarily from foods. Vitamin A: biomarkers of nutrition for development. What’s more, test-tube studies demonstrate that retinoids may inhibit the growth of certain cancer cells, such as bladder, breast and ovarian cancer (16). Vitamin A is … Vitamin A deficiency is one of the top causes of preventable blindness in children . Vitamin A promotes good eyesight, especially in low light. However, improved pancreatic replacement treatments, better nutrition, and caloric supplements have helped most patients with cystic fibrosis become vitamin A sufficient . 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