What are the dangers of taking too much vitamin A?
Taking more than 10,000 mcg a day of oral vitamin A supplements long term can cause:
- Bone thinning
- Liver damage
- Headache
- Diarrhea
- Nausea
- Skin irritation
- Pain in the joints and bone
- Birth defects
What is the primary function of vitamin A?
Vitamin A is the generic term for a group of fat-soluble compounds found in both animal and plant foods. Vitamin A is essential for your health, supporting cell growth, immune function, fetal development and vision. Perhaps one of the best-known functions of vitamin A is its role in vision and eye health.
What does vitamin A do for the human body?
Vitamin A is important for normal vision, the immune system, and reproduction. Vitamin A also helps the heart, lungs, kidneys, and other organs work properly. There are two different types of vitamin A. The first type, preformed vitamin A, is found in meat, poultry, fish, and dairy products.
Which vitamins should you be taking every day?
The Most Important Nutrients: Identifying What You Need
- Calcium. Throughout infancy, childhood, and adolescence, calcium is crucial for building strong teeth and bones.
- Potassium. Potassium is an essential nutrient that helps to regulate blood pressure. ...
- Magnesium. Magnesium is key for muscular and cardiovascular function, and for producing energy. ...
- Vitamin A. ...
- Vitamin C. ...
- Vitamin D. ...
- Vitamin E. ...
What does vitamin A do for the body?
Vitamin A (retinol, retinoic acid) is a nutrient important to vision, growth, cell division, reproduction and immunity. Vitamin A also has antioxidant properties.
What are the 5 major functions of vitamin A?
Vitamin A is needed for eye health, vision, immune function, cell growth, reproduction, and fetal development.
What disease can you get from lack of vitamin A?
Symptoms of a Vitamin A DeficiencyNight blindness. This causes you to have trouble seeing in low light. ... Xerophthalmia. With this condition, the eyes may become very dry and crusted, which may damage the cornea and retina.Infection. ... Bitot spots. ... Skin irritation. ... Keratomalacia. ... Keratinisation. ... Stunted growth.More items...•
What disease does vitamin A prevent?
Vitamin A may prevent some types of cancer and acne. It may also help treat psoriasis. It's also claimed to help treat dry or wrinkled skin. It may also protect against the effects of pollution and prevent respiratory tract infections.
Why is vitamin A important?
Vitamin A is essential for your health, supporting cell growth, immune function, fetal development and vision.
What is the leading cause of preventable blindness in children worldwide?
According to the WHO, vitamin A deficiency is the leading cause of preventable blindness in children worldwide. Vitamin A deficiency also increases the severity and risk of dying from infections like measles and diarrhea ( 18. Trusted Source.
How does vitamin A help the immune system?
Boosts Your Immune System. Vitamin A impacts immune health by stimulating responses that protect your body from illnesses and infections. Vitamin A is involved in the creation of certain cells, including B- and T-cells, which play central roles in immune responses that guard against disease.
Why is vitamin A important for male and female reproduction?
Vitamin A is essential for both male and female reproduction because it plays a role in sperm and egg development. It’s also critical for placental health, fetal tissue development and maintenance, as well as fetal growth ( 8. Trusted Source. ).
How many forms of vitamin A are there?
There are two forms of vitamin A found in food.
What is the active form of vitamin A?
Retinal, the active form of vitamin A, combines with the protein opsin to form rhodopsin, a molecule necessary for color vision and low-light vision ( 5 ).
Which vitamin is a potent antioxidant?
Potent Antioxidant. Provitamin A carotenoids such as beta-carotene, alpha-carotene and beta-cryptoxanthin are precursors of vitamin A and have antioxidant properties. Carotenoids fight free radicals — highly reactive molecules that can harm your body by creating oxidative stress ( 9. Trusted Source.
What is Vitamin A and What Does it Do?
Vitamin A is a fat-soluble vitamin naturally found in some foods or taken as a dietary supplement. It helps to keep your skin bright and your eyesight functioning. It's also vital for reproductive and immune health.
How Do I Increase My Vitamin A Intake?
Since vitamin A is found in so many different foods , deficiency is relatively rare unless you have a medical condition that interferes with activation or absorption. People who live in developing countries are also more at risk for malnutrition than in places like the United States.
Why is vitamin A important?
Adequate amounts of vitamin A are needed to keep your immune organs healthy and make immune cells that fight back against infections. Studies show that people with suboptimal vitamin A status are more likely to get sick or take longer to get well.
Where is vitamin A found?
Preformed vitamin A, or retinol and retinyl ester, is found in animal-based foods.
What are the micronutrients in the US?
Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington (DC): National Academies Press (US). 2001.
What is the maximum amount of vitamin A?
There is an upper limit for vitamin A of 3000 mcg for adults.
What is the benefit of vitamin A?
Vitamin A benefits nearly all the organs in your body. It supports the growth of the cells and tissues needed for organs like your heart, lungs, and kidneys to function.
How is vitamin A used in the body?
Vitamin A is a powerful antioxidant. As it moves through your body it scavenges damaging free radicals and fights inflammation.
How much vitamin A should you take?
First, you should always increase your vitamin A sources in your diet because that is the best and safest source of this nutrient. While eating foods high in beta-carotene is good, food with preformed vitamin A is even better. Where can you find vitamin A?
Why is vitamin A toxic?
Vitamin A toxicity is a concern – however, it could be due to a lack of synergistic vitamin D.
What are the concerns of vitamin A deficiency?
The World Health Organization lists its concerns for vitamin A deficiency, including: Strong recommendations for supplementation for neonates. Emphasis on vitamin A’s role in childhood development. Concern that worsening eyesight is due to low vitamin A levels during childhood.
Why is Vitamin A important?
Vitamin A Benefits that will Dramatically Improve Your Health. Vitamin A is an important and somewhat misunderstood nutrient. It’s critical to so many bodily functions and yet many of us don’t get enough of it. This is due to the combination of our dietary changes, the availability in our food sources, and our body’s fluctuating rates ...
How to get enough vitamin A?
Don’t eat organ meats. Eat a diet high in processed foods. You might think you can get sufficient vitamin A through vegetable, beta-carotene sources and supplements. To many people’s surprise, your body is unpredictable at making this conversion. Common signs of vitamin A deficiency include: Poor eye health.
What is the defining characteristic of vitamin A?
One of the defining characteristics of vitamin A is that it is fat soluble – meaning its dissolved, absorbed, and stored by fat tissue. Remember this if you’re looking to increase your vitamin A levels because you’ll significantly improve your body’s absorption if your source contains a fat.
What happens if you take vitamin A daily?
Taking more than 10,000 mcg a day of oral vitamin A supplements long term can cause: Bone thinning. Liver damage. Headache. Diarrhea. Nausea. Skin irritation. Pain in the joints and bone.
What is the role of vitamin A in the body?
Vitamin A (retinol, retinoic acid) is a nutrient important to vision, growth, cell division, reproduction and immunity. Vitamin A also has antioxidant properties. 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. Free radicals might play a role in heart disease, cancer and other diseases.
What happens if you don't take vitamin A?
This kind of deficiency isn't common in the United States. Vitamin A deficiency causes anemia and dry eyes.
Does vitamin A cause itchy skin?
Anticoagulants. Oral use of vitamin A supplements while taking these medications used to prevent blood clots might increase your risk of bleeding. Bexarotene (Targretin). Taking vitamin A supplements while using this topical cancer drug increases the risk of the drug's side effects, such as itchy, dry skin.
Is vitamin A good for you?
A healthy and varied diet will provide most people with enough vitamin A. If you're interested in the antioxidant properties of vitamin A, food sources are best. It's not clear if vitamin A supplements offer the same benefits as naturally occurring antioxidants in food. Too much vitamin A can be harmful and excess vitamin A during pregnancy has been linked to birth defects.
What vitamins are good for macular degeneration?
A large clinical trial showed that people at high risk of advanced age-related macular degeneration reduced their risk of developing the condition by 25 percent by taking a specific combination of vitamins that included beta-carotene. It's not entirely clear what role beta-carotene played.
Can you take vitamin A and retinol at the same time?
Retinoids. Don't use vitamin A supplements and these oral prescription drugs at the same time. This could increase the risk of high vitamin A blood levels. Nov. 13, 2020.
What Is Vitamin A?
Vitamin A is a fat-soluble nutrient that controls the growth of almost every cell in your body. You can get vitamin A naturally from certain foods. But, synthetic vitamin A can be consumed via fortified foods and supplements.
Why does my skin turn yellow?
Carotenemia can cause your skin to turn yellow, but it doesn't usually cause other symptoms. Even though carotene is converted to vitamin A in your body, excess carotene doesn't cause vitamin A toxicity. . Osteoporosis. Retinol intake of 1,500 micrograms of RAE or more every day might be related to osteoporosis. .
What are the different types of vitamins?
What Is Vitamin A? 1 Preformed vitamin A. Preformed vitamin A like retinol comes from animal products including liver, egg, fish, and dairy. 2 Provitamin A. Provitamin A like beta-carotene comes from plant sources and is converted into usable forms of vitamin A like retinol in your body. Provitamin A is found in carrots, tomatoes, cantaloupe, sweet potatoes, and leafy greens.
How much retinol is needed for men?
Using RAE tells you how much vitamin A your body converts into retinol. The recommended daily dose of vitamin A is 900 microgram s of RAE for men and 700 micrograms of RAE for women. Most people can easily get this in their regular diet without synthetic vitamin A supplements.
What are the effects of vitamin A deficiency?
A deficiency in vitamin A can cause fatigue, eye dryness, infertility, and blindness. Measles. Measles increases the chances of vitamin A deficiency.
What conditions increase the need for vitamin A?
Conditions that increase your need for vitamin A include pancreatic disease, certain eye diseases, and measles. If you take a multivitamin, you probably already take enough vitamin A and don't need additional supplementation. Multivitamins typically contain 750 to 3,000 micrograms of RAE..
What are the symptoms of vitamin A toxicity?
Symptoms include: Headache. Rash . Drowsiness. Abdominal pain. Nausea. Vomiting.
How much vitamin A should a child eat?
For a young child, a balanced diet that is rich in vitamin A should include helpings of at least 2–3 vitamin A-rich fruits and vegetables a day, plus a little bit of fat to aid absorption.
What is the role of vitamin A in the body?
Vitamin A is essential for many physiological processes, including maintaining the integrity and function of all surface tissues (epithelia): for example, the skin, the lining of the respiratory tract, the gut, the bladder, the inner ear and the eye. Vitamin A supports the daily replacement of skin cells and ensures that tissues such as the conjunctiva are able to produce mucous and provide a barrier to infection. Vitamin A is also essential for vision under conditions of poor lighting, for maintaining a healthy immune system, for growth and development and for reproduction. Vitamin A supports many systems in the body. For this reason, vitamin A deficiency is now referred to as vitamin A deficiency disorders. For simplicity, however, we will continue to use the older term vitamin A deficiency (VAD).
What is the color of plants?
Carotenoids are the pigments that give plants their green colour and some fruits and vegetables their red or orange colour.
What are the consequences of VAD?
One of the main consequences of VAD is an increased risk of severe infection. Infection increases the body's demand for vitamin A and so the deficiency gets worse. Children can therefore become involved in a vicious cycle of deficiency and infection, which is why vitamin A deficiency is such an important cause of child mortality.
What are the two main sources of vitamin A?
There are two main sources of vitamin A: animal sources and plant sources . All the sources of vitamin A need some fat in the diet to aid absorption.
Why do children need vitamin A?
Another reason for the relatively high intake is because children are prone to infection which increases the metabolic rate and hence the rate at which they use vitamin A.
Which foods are low in vitamin A?
Diets that rely heavily on local carbohydrates, such as rice, fufu, ugali, cassava, millet and sorghum, are very low in vitamin A, unless vitamin A-rich foods are added.
What is vitamin A and what does it do?
Vitamin A is a fat-soluble vitamin that is naturally present in many foods. Vitamin A is important for normal vision, the immune system, and reproduction. Vitamin A also helps the heart, lungs, kidneys, and other organs work properly.
How much vitamin A do I need?
The amount of vitamin A you need depends on your age and sex. Average daily recommended amounts are listed below in micrograms (mcg) of retinol activity equivalents (RAE).
What foods provide vitamin A?
Vitamin A is found naturally in many foods and is added to some foods, such as milk and cereal. You can get recommended amounts of vitamin A by eating a variety of foods, including the following:
What happens if I don’t get enough vitamin A?
Xerophthalmia is the inability to see in low light, and it can lead to blindness if it isn’t treated.
What are some effects of vitamin A on health?
Scientists are studying vitamin A to understand how it affects health. Here are some examples of what this research has shown.
What is the most common type of vitamin A?
The most common type of provitamin A in foods and dietary supplements is beta-carotene.
What is the purpose of vitamin A?
Vitamin A is important for normal vision, the immune system, and reproduction. Vitamin A also helps the heart, lungs, kidneys, and other organs work properly. There are two different types of vitamin A. The first type, preformed vitamin A, is found in meat, poultry, fish, and dairy products. The second type, provitamin A, is found in fruits, ...
How much vitamin A is in a multivitamin?
The amounts of vitamin A in stand-alone supplements range widely [ 2 ]. 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.
What are the two forms of vitamin A?
Two forms of vitamin A are available in the human diet: preformed vitamin A (retinol and its esterified form, retinyl ester) and provitamin A caro tenoids [1-5]. Preformed vitamin A is found in foods from animal sources, including dairy products, fish, and meat (especially liver). By far the most important provitamin A carotenoid is beta-carotene; other provitamin A carotenoids are alpha-carotene and beta-cryptoxanthin. The body converts these plant pigments into vitamin A. 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]. Other carotenoids found in food, such as lycopene, lutein, and zeaxanthin, are not converted into vitamin A.
What is vitamin A?
Vitamin A is the name of a group of fat-soluble retinoids, including retinol, retinal, and retinyl esters [1-3]. Vitamin A is involved in immune function, vision, reproduction, and cellular communication [1,4,5]. 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]. 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].
What is the source of vitamin A in the diet?
Table 2 suggests many dietary sources of vitamin A. 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.
How many IUs is a 900 mg RAE?
This RDA is also equivalent to 18,000 IU beta-carotene from food or to 36,000 IU alpha-carotene or beta-cryptoxanthin from food. Therefore, a mixed diet containing 900 mcg RAE provides between 3,000 and 36,000 IU vitamin A, depending on the foods consumed.
Where is vitamin A stored?
Most of the body's vitamin A is stored in the liver in the form of retinyl esters.
How much vitamin A is in cereal?
Breakfast cereals, fortified with 10% of the DV for vitamin A, 1 serving
What is the role of B cells in humoral homeostasis?
Antibody production by B cells is central to humoral homeostatic maintenance. Antibodies represent a specific class of immunoglobulins. Animal experiments have demonstrated that the addition of carotenoid-rich foods to rabbit diets can increase their serum levels of IgG, IgM, and IgA, thereby enhancing humoral immunity [90]. Further studies in rat have revealed the association between a paucity of VitA in the diet and increased number of DCs, in addition to the significantly upregulated expression of IL-12, Toll-like receptor 2, and myeloid differentiation factor MyD88 in the intestinal mucosa. When the levels of secretory IgA decrease, rats display a decreased immune function, suggesting that VitA is involved in the synthesis of immunoglobulins, and has an important influence on humoral immunity [91]. A report shows that RA potently synergized with gut-associated lymphoid tissues DC-derived IL-6 or IL-5 to induce IgA secretion [92]. A knockout study demonstrated that the ablation of RARα reduces IgA expression by B cells expressed in vivo and in vitro. This indicates that RA acts on B cells directly through RARα, which affects the synthesis and secretion of IgA [93]. It is also likely that RA affects Tregs first, and then indirectly modulates B cells, since Tregs have an important role in regulating B cell responses [94].
What is the RA ligand?
RA is the ligand of the nuclear retinoic acid receptor (RAR) protein. RAR family has three main members (α(isoforms a1-2), β(isoforms b1-4), and γ), which have additional subtypes produced by the use and splicing of alternating promoters [8]. The nuclear RAR acts as a ligand-activating transcription factor, regulating gene transcription according to cell type and tissue [9]. The ATRA is the highest affinity endogenous ligand of RAR [10]. A member of the second protein family, RA-X receptor (RXR) heterodimers and RAR, give high affinity to binding DNA. The RXR family also contains three members (RXRα, RXRβ, and RXRγ). In addition to targeting RARα, RARβ, and RARγ-like ATRA, 9-cis-RA also activates RXRα, RXRβ, and RXRγ [11]. RAR/RXR heterologous two dimer-bound DNA is known as the retinoic acid reaction element. The consensus retinoic acid reaction element is composed of two direct repeats of PuG (G/T) and TCA that are most often separated by 5 bases [12]. RAR acts as an enhancer, and promotes chromatin opening and changes in the transcriptional activity of RA target genes when occupied by RA/RAR/RXR complexes [13,14]. Binding of RA to RAR leads to release of the corepressor complex and association with coactivator proteins, followed by altered transcription of downstream target genes and, ultimately, changes in cellular function. RA also undergoes further oxidation by the cytochrome P450 (CYP26) family to more polar metabolites. The lipophilic molecule, RA, can act within the same cell in which it is synthesized (autocrine), or can act in a paracrine manner in nearby cells [15,16,17].
How does retinol turn into a bioactive retinol?
Transformation of retinol into bioactive retinoic acid involves a two-step oxidative reaction. To do this, a group of enzymes, divided in three families, will act together to form the final compound retinoic acid (RA). Retinol transforms into retinal under the catalytic action of the alcohol dehydrogenase (ADH) family; this step can also be regulated by the short-chain dehydrogenase/reductase family, which shows a wide affinity for alcohols and aldehydes. The aldehyde dehydrogenase (RALDH) family then catalyzes retinal to form retinoic acid. Both of the oxidation reactions transmit electrons through the electron acceptor NAD or NADP.
What is RA in a cell?
6.2. RA Is a Control Factor for Regulatory T Cells and Maintains Its Homeostasis
What is Vita involved in?
3. VitA Is Involved in the Formation of the Epithelial and Mucous Tissues
What is Vita in the body?
Vitamin A (VitA) is a micronutrient that is crucial for maintaining vision, promoting growth and development, and protecting epithelium and mucus integrity in the body. VitA is known as an anti-inflammation vitamin because of its critical role in enhancing immune function. VitA is involved in the development of the immune system and plays regulatory roles in cellular immune responses and humoral immune processes. VitA has demonstrated a therapeutic effect in the treatment of various infectious diseases. To better understand the relationship between nutrition and the immune system, the authors review recent literature about VitA in immunity research and briefly introduce the clinical application of VitA in the treatment of several infectious diseases.
Where is RA produced?
As mentioned above, RA is mainly produced by DC from the gut. Some reports show that RA may also be produced at other sites during an ongoing immune response [66,81,82]. We have discussed that RA signaling is initiated during the development of inflammation. Similarly, there is evidence demonstrating that the RA–RARα signaling axis is essential for adaptive CD4+ T cell immunity as RARα-deficient CD4+ T cells were less efficient than wild-type counterparts in polyclonal activation. Also, in RARα-deficient T cells, the phosphorylation of PLCγ and ERK1/2 was reduced, and manifests impaired Ca2+mobilization and mTOR/AKT activation upon T cell stimulation. Together, RARα may regulate the signaling pathways downstream of T cell receptor engagement [83].