Vitamin A
Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids. Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vi…
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 main function of vitamin A?
What are the 5 major functions of vitamin A?
- Vision. Vitamin A is required for the maintenance of normal vision.
- Immune system. Related Stories.
- Cell growth.
- Gene transcription and protein formation.
- Skin health.
- Further Reading.
What are the benefits and sources of vitamin A?
Vitamin A: Benefits and Food Sources of this Essential Nutrient
- Food sources of vitamin A. There are two different types of vitamin A found in food: preformed vitamin A, and provitamin A carotenoids.
- Our favorite vitamin A rich food sources. ...
- Recommended daily intake for vitamin A. ...
- Absorption rates. ...
- Our vitamin A. ...
- Stop guessing, start measuring. ...
How does vitamin A help the body?
What Does Vitamin A Do?
- Healthy Vision. The main function of vitamin A is to support vision, especially in dim lighting, by creating pigments that are needed to help keep the retina of the eye ...
- Bones, Skin and Immune function. ...
- Vitamin A Deficiency. ...
- Vitamin A Toxicity. ...
- Sources and Recommended Intakes. ...
What disease is prevented by vitamin A?
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.
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.
How does vitamin A help immune system?
Vitamin A plays a vital role in maintaining your body's natural defenses. This includes the mucous barriers in your eyes, lungs, gut and genitals which help trap bacteria and other infectious agents.
Can Too Much vitamin cause hair loss?
Yes, overdoing vitamins and nutritional supplements can cause hair loss. In addition to excessive selenium, taking too much Vitamin A can also cause hair loss. Overall, it's best not to exceed the upper recommendation limit for vitamins because too much can cause a variety of health problems.
Before Taking This Medicine
Before using vitamin A, talk to your doctor, pharmacist, herbalist, or other healthcare provider. You may not be able to use vitamin A if you have...
How Should I Take Vitamin A?
Use exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.Swall...
What Happens If I Miss A Dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to...
What Happens If I Overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of vitamin A can cause serious or life-threatening sid...
What Other Drugs Will Affect Vitamin A?
Do not take vitamin A without your doctor's advice if you are also taking: 1. birth control pills; 2. a blood thinner such as warfarin (Coumadin, J...
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 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 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.
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.
Can vitamin A cause liver damage?
Taking high doses of vitamin A supplements can cause liver damage. Combining high doses of vitamin A supplements with other drugs that can damage the liver could increase the risk of liver disease. Orlistat (Alli, Xenical). This weight-loss drug can decrease the absorption of food sources of vitamin A.
Why do people take vitamin A?
People also use vitamin A to reduce complications of diseases such as malaria, HIV /AIDS, and measles, and for fertility, diarrhea, vision, child development, skin disorders, infections, and many other conditions, but there is no good scientific evidence to support most of these uses.
What is the UL of vitamin A?
The tolerable Upper Intake Level (UL) for vitamin A is 10,000 units (3,000 mcg) daily. The UL is the highest level of intake that is likely to pose no risk of harmful effects. The UL for vitamin A is for preformed vitamin A (retinol) and does not include provitamin A carotenoids.
How does it work ?
Vitamin A is required for the proper development and functioning of our eyes, skin, immune system, and many other parts of our bodies.
How long does vitamin A help with ulcerative colitis?
A type of inflammatory bowel disease ( ulcerative colitis ). Some research shows that taking vitamin A daily for 2 months can reduce symptoms and help the intestine to heal in adults with ulcerative colitis. Skin wrinkles from sun damage.
What is the difference between vitamin A and carotenoids?
Vitamin A is a fat -soluble vitamin . It can be found in many fruits, vegetables, eggs, whole milk, butter, fortified margarine, meat, and oily saltwater fish. It can also be made in a laboratory. Carotenoids are a group of yellow or orange chemicals found in plants.
How long can you use 0.5% serum?
When applied to the skin: Vitamin A is POSSIBLY SAFE when used on the skin, short-term. Retinol 0.5% serum has been used daily for up to 12 weeks without serious side effects. When given as a shot: Vitamin A is LIKELY SAFE when given as a shot into the muscle in amounts less than 10,000 units (3,000 mcg) daily.
How much vitamin A is safe?
Side Effects. When taken by mouth: Vitamin A is LIKELY SAFE for most people in amounts less than 10,000 units (3,000 mcg) daily . Keep in mind that vitamin A is available in two different forms: pre-formed vitamin A and provitamin A.
Why is vitamin A important?
Vitamin A is essential for your health, supporting cell growth, immune function, fetal development and vision.
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.
Where is vitamin A stored?
Because vitamin A is fat soluble, it’s stored in body tissue for later use. Most of the vitamin A in your body is kept in your liver in the form of retinyl esters ( 3. Trusted Source. ). These esters are then broken down into all-trans-retinol, which binds to retinol binding protein (RBP).
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 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.
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 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.
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 RDA for nutrition?
Recommended Dietary Allowance (RDA): Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy individuals; often used to plan nutritionally adequate diets for individuals.
What Is Vitamin A Deficiency?
Vitamin A deficiency typically occurs when a person does not consume enough foods rich in vitamin A to meet their body's required needs.
Signs and Symptoms
Depending on the severity of the deficiency, signs and symptoms may vary. The most common symptom of vitamin A deficiency in pregnant women and children is xeropthalmia .
Causes and Risk Factors
Pregnant and breastfeeding people, infants, and young children in developing countries are at the highest risk of vitamin A deficiency. An estimated 50% of pre-school-aged kids and pregnant mothers worldwide are at risk.
Complications
Over time, vitamin A deficiency can lead to complications if left untreated.
Diagnosis and Evaluation
Vitamin A deficiency is more common if you have an underlying condition that puts you at a higher risk for developing a deficiency in fat-soluble vitamins. If that's the case, you should have regular screenings to ensure you have no nutrient deficiencies.
Treatment and Prevention
The best way to prevent a vitamin A deficiency is to eat a nutrient-rich, well-balanced diet. The Recommended Dietary Allowances (RDA) for Vitamin A are listed in micrograms of retinol activity equivalents (RAE), which considers the different absorption rates of both forms of vitamin A.
Summary
While vitamin A deficiencies are rare in developed countries like the United States, they still exist. You may have trouble absorbing nutrients because of an underlying health issue, or you may experience symptoms associated with vitamin A deficiency.
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.
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 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 are the symptoms of vitamin A toxicity?
Symptoms include: Headache. Rash . Drowsiness. Abdominal pain. Nausea. Vomiting.
What foods are good for vitamin A?
Leafy greens. Orange and yellow vegetables. Tomatoes. Cantaloupe. Apricots. . Getting your vitamin A through food rather than supplements is ideal. The health benefits of vitamin A from food sources are well established, but the benefits from synthetic supplements are not as clear. .
Why is vitamin A important for the immune system?
Because it helps the production of white blood cells, vitamin A is necessary for a healthy immune system. Vitamin A is also known as retinol, and its derivatives (whether natural or manufactured) are called retinoids.
What are the derivatives of vitamin A?
There are three derivatives of vitamin A: retinol, retinal, and tretinoin. Retinol is available over the counter to treat photodamaged skin (skin damage from the sun) and aging skin. Retinal is a less irritating form and is important for vision.
What is the best vitamin for aging skin?
Vitamin A’s current status as an anti-aging skin marvel dates back to the 1980s when researchers found that the derivative tretinoin (brand name Retin-A) helped boost collagen production in mice when applied topically to photoaged skin —that is, skin prematurely aged through exposure to ultraviolet light from the sun. Coinciding with this discovery was the observation by doctors prescribing tretinoin for acne that patients had smoother skin, with fewer wrinkles. Tretinoin was later found to interfere with the enzymes that work to break down collagen in the dermal layer of skin and to promote the manufacture of new collagen.
How long does it take for tretinoin to work?
It can take a few months for these positive results to appear, and the effects are dose-dependent, meaning stronger concentrations bring noticeable results more quickly.
What are the factors that affect the effectiveness of tretinoin?
Other factors affecting how well tretinoin works include genetics, individual skin quality, and the extent of photodamage.
Does tretinoin help with acne?
Coinciding with this discovery was the observation by doctors prescribing tretinoin for acne that patients had smoother skin, with fewer wrinkles. Tretinoin was later found to interfere with the enzymes that work to break down collagen in the dermal layer of skin and to promote the manufacture of new collagen.
Is vitamin A derivative backed by research?
They, therefore, are not backed by research published in scholarly journals and are difficult to review.
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.
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
Is Vita a monohydric alcohol?
Vitamin A (VitA) is a group of unsaturated monohydric alcohols that contain an alicyclic ring. VitA is insoluble in water but is fat soluble [1]. In 1928, Green and Mellandy reported that VitA could enhance the anti-inflammatory response of organisms and called VitA the “anti-inflammation vitamin” [2]. Later, the anti-inflammatory capacity of VitA was widely studied in the 1980s and 1990s [3,4,5]. VitA exists in the form of retinol, retinal, and retinoic acid (RA), among which RA shows the most biological activity. RA exists in two significant derivatives: 9-cis-RA and all-trans-RA (ATRA) [6] (Figure 1). The primary biological functions of VitA include maintenance of vision, growth, and the integrity of epithelial and mucous tissue [7]. However, the immunoregulatory mechanisms of VitA are not entirely understood. The authors, here, conduct a detailed review on the most recent advances of VitA function in immunology. We briefly introduce the clinical application of VitA in the treatment of several contagious diseases to provide theoretical support for VitA research in immunology and its therapeutic applications.
Can VitC help with AIDS?
AIDS patients are known, in general, to be deficient in many vitamins [113]. Since various vitamins have the potential to enhance the immunity of the organism and because AIDS arises from human immunodeficiency virus infection, oxidative stress is thought to have an important effect on the infection process of HIV virus [114,115]. VitA, VitC, and VitE are all-natural antioxidants, and by inhibiting the oxidative stress of the organism, it is postulated that these vitamins can ameliorate the progression of AIDS.
Does Vita affect tuberculosis?
A longitudinal cohort study of tuberculosis showed that VitA deficiency is dose-dependently correlated to the occurrence of tuberculosis [109]. An in vitro study demonstrated that RA inhibits the growth of M. tuberculosisand reduces its survival rate when engulfed by macrophages [110]. For the mechanism of bacteriocidic activity of VitA, Wheelwright et al. found that VitA can induce the expression of NPC2. In NPC2 gene knockout cells, the stimulation of VitA showed no bacteriocidic activity on infected cells. However, the NPC2 gene is commonly known as a regulator of cholesterol transport rather than an immunological regulatory factor. This result can be explained as follows: cholesterol is the nutritional source for tuberculosis bacterial cell walls, whereas NPC2 facilitates the transportation of cholesterol out of lysosomes, therefore depriving tuberculosis bacteria of their nutritional needs. Without the ability of M. tuberculosisto generate protective cell walls, lysozyme can then effectively kill this pathogen [111]. This was demonstrated in a mouse model of tuberculosis in which the addition of ATRA significantly improved the efficacy of traditional anti-tuberculosis drugs [112]. However, more research will be required to elucidate the positive effects ofVitA supplements on the treatment of tuberculosis.
