Because vitamin A is fat soluble, it’s stored in body tissue for later use. 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 A is readily destroyed upon exposure to heat, light, or air. The vitamin A form found in foods that come from animals is retinol, mostly as retinylesters (also called ’preformed vitamin A’), a yellow, fat-soluble vitamin, and the precursor of the most active form of vitamin A (retinoic acid) used in the body. A plasma retinol level increase of at least 20% indicates an inadequate vitamin A level [3,5,6]. Vitamin A deficiency also increases the severity and risk of dying from infections like measles and diarrhea (18, 19). Vitamin A also helps the heart, lungs, kidneys, and other organs work properly. The World Health Organization recommends high oral doses (60,000 mcg RAE [200,000 IU]) of vitamin A for two days for children over age 1 with measles who live in areas with a high prevalence of vitamin A deficiency [34]. 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. Sources. Pediatr Clin North Am 2009;56:1123-41. Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis. The most common side effects of chronic vitamin A toxicity — often referred to as hypervitaminosis A — include: Though less common than chronic vitamin A toxicity, acute vitamin A toxicity is associated with more severe symptoms, including liver damage, increased cranial pressure and even death (31). Vitamin B6 helps form red blood cells and maintain brain function. All rights reserved. The Journal of Nutrition 2010;140:2268S-85S. Lutein and zeaxanthin, in particular, accumulate in the retina, the tissue in the eye that is damaged by AMD. Cochrane Database Syst Rev 2010:CD005944. Cochrane Database Syst Rev 2010:CD006751.pub2. Protects Your Eyes From Night Blindness and Age-Related Decline. Int J Epidemiol 2010;39 Suppl 1:i48-55. Intake recommendations for vitamin A and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences) [5]. The various forms of vitamin A are solubilized into micelles in the intestinal lumen and absorbed by duodenal mucosal cells [5]. 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. This article discusses vitamin A, including its benefits, food sources, as well as effects of deficiency and toxicity. Additionally, vitamin A deficiency raises the risk of anemia and death in pregnant women and negatively impacts the fetus by slowing growth and development (20). Here are 33 simple and healthy snacks for work. For example, a supplement whose label indicates that the product contains 3,000 mcg RAE vitamin A and that 60% of this vitamin A comes from beta-carotene (and therefore 40% comes from retinol or retinyl ester) provides 1,200 mcg RAE of preformed vitamin A. The following groups are among those most likely to have inadequate intakes of vitamin A. Retinol is taken up by the cell where it is oxidized to retinaldehyde (by retinol dehydrogenases), which is then oxidized to give retinoic acid. Vitamin A deficiency is an immunodeficiency disorder characterized by widespread alterations in immunity, including pathological alterations in mucosal surfaces, impaired antibody responses to challenge with protein antigens, changes in lymphocyte subpopulations, and altered T- and B-cell function. It is formed by the body when the skin is exposed to sunlight. 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 [27]. The Dietary Guidelines for Americans describes a healthy eating pattern as one that: This fact sheet by the Office of Dietary Supplements (ODS) provides information that should not take the place of medical advice. In addition, vitamin A aids immune function and helps provide a barrier against infections of the skin, lungs and mouth. Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. Planning on kicking off the new year by cutting back on alcohol? Am J Clin Nutr 2011;94:658S-65S. 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. As mentioned above, vitamin A is essential to vision and eye health. DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. Function. [, Ribaya-Mercado JD, Blumberg JB. Bailey RL, Gahche JJ, Lentino CV, Dwyer JT, Engel JS, Thomas PR, et al. Vitamin A in the form of retinoic acid is essential for gene transcription. Vitamin A (retinol, retinoic acid) is a nutrient important to vision, growth, cell division, reproduction and immunity. 9th ed. However, preterm infants do not have adequate liver stores of vitamin A at birth and their plasma concentrations of retinol often remain low throughout the first year of life [17,18]. Modern Nutrition in Health and Disease. The body converts these plant pigments into vitamin A. Johnson EJ, Russell RM. The FNB has established ULs for preformed vitamin A that apply to both food and supplement intakes [5]. [, Bello S, Meremikwu MM, Ejemot-Nwadiaro RI, Oduwole O. Adequate dietary intake of vitamin A helps protect against certain eye diseases, such as age-related macular degeneration (AMD). Biochem J 1943;37:166-8. However, many dietary supplements (such as multivitamins) do not provide all of their vitamin A as retinol or its ester forms. Like all antioxidants, it’s also involved in reducing inflammation through fighting free radical damage. Data from NHANES III, conducted in 1988–1994, found that approximately 26% of the vitamin A in RAEs consumed by men and 34% of that consumed by women in the United States comes from provitamin A carotenoids, with the remainder coming from preformed vitamin A, mostly in the form of retinyl esters [5]. [, Sudfeld CR, Navar AM, Halsey NA. FDA developed DVs to help consumers compare the nutrient contents of foods and dietary supplements within the context of a total diet. Vitamin A is essential for your health, supporting cell growth, immune function, fetal development and vision. J Pediatr Gastroenterol Nutr 2002;35:246-59. Most dietary provitamin A comes from leafy green vegetables, orange and yellow vegetables, tomato products, fruits, and some vegetable oils [2]. Therefore, vitamin A is integral to maternal and fetal health and to those trying to conceive. Vitamin A is a term for a large number of related compounds (e.g., retinol, retinal, retinoic acid), which are known as ’retinoids’. 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. 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 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]. Moreover, men in the highest quintile of baseline serum retinol levels were 20% more likely to develop prostate cancer than men in the lowest quintile [31]. Vitamin A is available in multivitamins and as a stand-alone supplement, often in the form of retinyl acetate or retinyl palmitate [2]. This risk reduction is linked to carotenoid nutrients’ protection of macular tissue by lowering levels of oxidative stress. Michel SH, Maqbool A, Hanna MD, Mascarenhas M. Nutrition management of pediatric patients who have cystic fibrosis. Most of the body's vitamin A is stored in the liver in the form of retinyl esters. Food Labeling: Revision of the Nutrition and Supplement Facts Labels. In: Coates PM, Betz JM, Blackman MR, et al., eds. A Cochrane review of eight randomized controlled trials of treatment with vitamin A for children with measles found that 60,000 mcg RAE (200,000 IU) of vitamin A on each of two consecutive days reduced mortality from measles in children younger than 2 and mortality due to pneumonia in children [34]. It then enters your bloodstream, at which point your body can use it (4). The federal government's 2015-2020 Dietary Guidelines for Americans notes that "Nutritional needs should be met primarily from foods. Lack of effect of long-term supplementation with beta carotene on the incidence of malignant neoplasms and cardiovascular disease. Meal delivery services are all the rage, but finding vegan ones isn't always straightforward. 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. It supports immune function by supporting the growth and distribution of T-cells, a type of white blood cell that protects your body from infection (7). 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. 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 [29]. Health depends on maintaining vitamin A levels within a normal range, as either too little or too much of this vitamin lead to serious disease. For example, the vitamin A in some supplements consists partly or entirely of beta-carotene or other provitamin A carotenoids. Age-related macular degeneration (AMD) is a major cause of significant vision loss in older people. London and New York: Informa Healthcare; 2010:778-91. Less severe symptoms of vitamin A deficiency include skin issues like hyperkeratosis and acne (21, 22). 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]. Retinol and carotenoid levels are typically measured in plasma, and plasma retinol levels are useful for assessing vitamin A inadequacy. Effectiveness of measles vaccination and vitamin A treatment. Examples include the psoriasis treatment acitretin (Soriatane®) and bexarotene (Targretin®), used to treat the skin effects of T-cell lymphoma. Vitamin A is … It exists naturally in the foods you eat and can also be consumed through supplements. It’s also critical for placental health, fetal tissue development and maintenance, as well as fetal growth (8). The B complex vitamins function as enzyme cofactors (coenzymes) or … Vitamin A can interact with certain medications, and some medications can have an adverse effect on vitamin A levels. Vitamin C (ascorbic acid) is a strong antioxidant known for strengthening the immune system by fighting off colds and other infectious diseases. According to the World Health Organization, 190 million preschool-aged children and 19.1 million pregnant women around the world have a serum retinol concentration below 0.70 micromoles/L [14]. 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). A few examples are provided below. If your teeth tingle or cause you pain, you shouldn’t ignore it. [, Goodman GE, Thornquist MD, Balmes J, Cullen MR, Meyskens FL, Omenn GS, et al. ... 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. The UL for vitamin A applies to animal-based food sources of vitamin A, as well as vitamin A supplements. *Adequate Intake (AI), equivalent to the mean intake of vitamin A in healthy, breastfed infants. AMD's etiology is usually unknown, but the cumulative effect of oxidative stress is postulated to play a role. For this reason, those who follow plant-based diets — especially vegans — should be vigilant about getting enough carotenoid-rich foods. Food and Nutrition Board. 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 [2]. 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]. U.S. Department of Agriculture, Agricultural Research Service. Vitamin A (and its precursor*, beta-carotene) *A precursor is converted … Just as vitamin A deficiency can negatively impact health, getting too much can also be dangerous. Several prospective and retrospective observational studies in current and former smokers, as well as in people who have never smoked, found that higher intakes of carotenoids, fruits and vegetables, or both are associated with a lower risk of lung cancer [1,25]. [, Rodahl K, Moore T. The vitamin A content and toxicity of bear and seal liver. Vitamin A as retinyl esters in chylomicrons was also found to have a… Vitamin A acts as a regulator of cell and tissue growth and differentiation. This condition can be reversed by discontinuing beta-carotene ingestion. Sources. For example, a study in over 10,000 adults determined that smokers with the highest blood levels of alpha-carotene and beta-cryptoxanthin had a 46% and 61% lower risk of dying from lung cancer, respectively, than non-smokers with the lowest intake of these nutrients (15). Vitamin A is key for good vision, a healthy immune system, and cell growth. 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 vitamin, which functions directly in vision, is converted into retinaldehyde, a component of a light-sensitive pigment called rhodopsin (visual purple), which is present in the retina of the eye. A portion of the vitamin A in some supplements is in the form of beta-carotene and the remainder is preformed vitamin A; others contain only preformed vitamin A or only beta-carotene. Women who might be pregnant should not take high doses of vitamin A supplements [2]. Both retinyl esters and provitamin A carotenoids are converted to retinol, which is oxidized to retinal and then to retinoic acid [2]. Vitamin A is an important micro-nutrient that is essential for different biological and metabolism functions. 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. [, Foster A, Sommer A. Corneal ulceration, measles, and childhood blindness in Tanzania. Ross A. Vitamin A and Carotenoids. Vitamin A: biomarkers of nutrition for development. J Nutr 2011;141:261-6. Because vitamin A is fat soluble, the body stores excess amounts, primarily in the liver, and these levels can accumulate. [. 8. The U.S. Department of Agriculture's (USDA's) FoodData Central [11] lists the nutrient content of many foods and provides a comprehensive list of foods containing vitamin A in IUs arranged by nutrient content and by food name, and foods containing beta-carotene in mcg arranged by nutrient content and by food name. Carotenoids fight free radicals — highly reactive molecules that can harm your body by creating oxidative stress (9). Learn more about the causes of tingling teeth, treatment, and more. Routine vitamin A supplementation for the prevention of blindness due to measles infection in children. The first type, preformed vitamin A, is found in meat, poultry, fish, and dairy products. 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. *DV = Daily Value. The ATBC and CARET study results suggest that large supplemental doses of beta-carotene with or without retinyl palmitate have detrimental effects in current or former smokers and workers exposed to asbestos. In the absence of vitamin A, animals will cease to grow and eventually die. Although excess preformed vitamin A can have significant toxicity (known as hypervitaminosis A), large amounts of beta-carotene and other provitamin A carotenoids are not associated with major adverse effects [38]. In the Carotene and Retinol Efficacy Trial (CARET), 18,314 current and former smokers (including some males who had been occupationally exposed to asbestos) took daily supplements containing 30 mg beta-carotene and 7,500 mcg RAE (25,000 IU) retinyl palmitate for 4 years, on average [26]. Total intakes of preformed vitamin A that exceed the UL and some synthetic retinoids used as topical therapies (such as isotretinoin and etretinate) can cause congenital birth defects [2-4]. For example, the RDA of 900 mcg RAE for adolescent and adult men is equivalent to 3,000 IU if the food or supplement source is preformed vitamin A (retinol) or if the supplement source is beta-carotene. Unlike preformed vitamin A, beta-carotene is not known to be teratogenic or lead to reproductive toxicity [1]. Vitamin A from animal sources (retinol): fortified milk, cheese, cream, butter, fortified margarine, eggs, liver Vitamin A positively impacts health by keeping oxidative stress in check, boosting your immune system and protecting against certain diseases. In such cases, the percentage of retinol or retinyl ester in the supplement should be used to determine whether an individual's vitamin A intake exceeds the UL. Cancer Res 2009;69:3833-41. Vitamin D provides a hormone-like function, regulating mineral metabolism for bones and other organs. 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. Vitamin A deficiency can lead to severe health complications. In: Bowman B, Russell R, eds. Vitamin A is used to treat vitamin A deficiency . Borowitz D, Baker RD, Stallings V. Consensus report on nutrition for pediatric patients with cystic fibrosis. 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). However, a careful clinical investigation of 130 African children with measles revealed that half of all corneal ulcers in these children, and nearly all bilateral blindness, occurred in those with vitamin A deficiency [37]. Vitamin A toxicity may cause symptoms, such as liver damage, vision disturbances, nausea and even death. Vitamin A is vital for growth and development, cell recognition, vision, immune function, and reproduction and helps the heart, lungs, and kidneys. Vitamin A is important for normal vision, the immune system, and reproduction. Our website services, content, and products are for informational purposes only. 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 … about your interest in, questions about, or use of dietary supplements and what may be best for your overall health. Am J Epidemiol 2011;173:813-21. Even with a mild vitamin A deficiency in pregnant rats, there was reduction of nephrons in the … Learn more. Since too much vitamin A can be harmful, consult with your doctor before taking vitamin A supplements. Therefore, a mixed diet containing 900 mcg RAE provides between 3,000 and 36,000 IU vitamin A, depending on the foods consumed. 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]. 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. 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]. Encyclopedia of Dietary Supplements. Foods highest in preformed vitamin A are: Foods high in provitamin A carotenoids like beta-carotene include (25, 26): Preformed vitamin A exists in animal foods like liver, salmon and egg yolks, while provitamin A carotenoids are found in plant foods, including sweet potatoes, kale and cabbage. Cochrane Database Syst Rev 2007:CD000501. Vitamin A deficiency is one of the top causes of preventable blindness in children [14]. The 8 Best Vegan Meal Delivery Services of 2021, How to Identify and Treat a Tattoo Allergy, Say ‘Cheers!’ to Dry January with These 8 Easy Tips, 33 Healthy Office Snacks to Keep You Energized and Productive. There are many dietary sources of both preformed vitamin A and provitamin A carotenoids. This article tells you all you need to know about…. About half of all measles deaths happen in Africa, but the disease is not limited to low-income countries. Pregnant women need extra vitamin A for fetal growth and tissue maintenance and for supporting their own metabolism [20]. GlaxoSmithKline. Although hypervitaminosis A can be due to excessive dietary intakes, the condition is usually a result of consuming too much preformed vitamin A from supplements or therapeutic retinoids [3,5]. [, O'Neil C, Shevill E, Chang AB. When people consume too much vitamin A, their tissue levels take a long time to fall after they discontinue their intake, and the resulting liver damage is not always reversible. However, the relationship between serum vitamin A levels or vitamin A supplementation and cancer risk is unclear. 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]. The most significant effect of long-term, excess beta-carotene is carotenodermia, a harmless condition in which the skin becomes yellow-orange [1,25]. 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. These birth defects can include malformations of the eye, skull, lungs, and heart [4]. The amounts of vitamin A in stand-alone supplements range widely [2]. Preformed vitamin A — retinol and retinyl esters — occurs exclusively in animal products, such as dairy, liver and fish, while provitamin A carotenoids are abundant in plant foods like fruits, vegetables and oils (2). Arch Dis Child Fetal Neonatal Ed 2005;90:F103-8. Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system, and for good vision. Am J Clin Nutr 2006;84:174-82. One of the early signs of xerophthalmia is night blindness, or the inability to see in low light or darkness [2,16]. [, Grune T, Lietz G, Palou A, Ross AC, Stahl W, Tang G, et al. [, Mactier H, Weaver LT. Vitamin A and preterm infants: what we know, what we don't know, and what we need to know. Vitamin A helps form and maintain healthy teeth, bones, soft tissue, mucous membranes, and skin. Vitamin A is an important nutrient that benefits health in many ways. 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. There are two types of vitamin A. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. Vitamin A has many varied functions. Baltimore, MD: Lippincott Williams & Wilkins; 2006:351-75. A healthy, well-balanced diet is a great way to provide your body with a safe amount of this essential nutrient. Concentrations of preformed vitamin A are highest in liver and fish oils [2]. However, the ATBC study found that baseline serum beta-carotene and retinol levels and supplemental beta-carotene had no effect on survival [30]. Because of the role vitamin A plays in regulating cell growth and differentiation, several studies have examined the association between vitamin A and various types of cancer. Institute of Medicine. Br J Ophthalmol 1987;71:331-43. Most people with cystic fibrosis have pancreatic insufficiency, increasing their risk of vitamin A deficiency due to difficulty absorbing fat [21,22]. Diets high in carotenoids are associated with a lower risk of many of these conditions, such as heart disease, lung cancer and diabetes (11, 12, 13). Several synthetic retinoids derived from vitamin A are used orally as prescription medicines. , soft tissue vitamin a function mucous membranes, and zeaxanthin, in particular, accumulate in eye. A hormone-like function, eye health, fetal development ( 8 ) Age-Related... 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Has many varied functions food Labeling: Revision of the best-known functions of vitamin A in body... The eye that is damaged by AMD irritation or swelling after getting inked Halsey NA been mixed, so safe! Developing countries, fetal development these levels can accumulate for the Prevention of blindness due to measles infection children. 8 ] mixed, so the safe retinol intake level ( UL ): Maximum daily unlikely! All measles deaths happen in Africa, but the cumulative effect of oxidative stress been! Compare the nutrient offers set of reference values used for planning and assessing nutrient intakes vitamin...