vitamin A


Definition of vitamin A 

: any of several fat-soluble vitamins (such as retinol) that are found especially in green or orange vegetables (such as carrots or spinach) and in animal products (such as egg yolk, butter, or liver) and whose deficiency in the animal body causes epithelial tissues to become keratinous (as in the eye with resulting visual defects)

Examples of vitamin A in a Sentence

Recent Examples on the Web

One cup of mangos is 100 calories and provides 100 percent of vitamin C, 20 percent of folate, 35 percent of vitamin A and a smattering of calcium, copper and iron. Sheah Rarback, miamiherald, "Ubiquitous mangos taste good - and are good for you, too," 29 June 2018 For example, vitamin A in excess amounts can cause headaches, while excess iron can cause nausea, per the NIH. Carolyn L. Todd, SELF, "Primary Care Doctors Share 9 Ways to Get the Most Out of Your Annual Checkup," 31 May 2018 Some use chlorophyll to convert sunlight during photosynthesis and others use rhodopsins, proteins that bind to a form of vitamin A called retina to capture light. Shandria Sutton, Science | AAAS, "New ‘light-eating’ protein discovered in the Sea of Galilee," 5 July 2018 The vitamin A in mangos can add a sheen to your hair. Sheah Rarback, miamiherald, "Ubiquitous mangos taste good - and are good for you, too," 29 June 2018 While fresh peas are a good source of fiber, thiamine, folate, manganese, and vitamins A, C, and K, one cup of green peas contains 8.6 grams of protein, less than half of what you’d get from a serving of some of the most common pea protein powders. Sara Angle, Outside Online, "Pea Protein Is the Best Protein," 19 June 2018 Instead of using chemicals to extract plant nutrients (such as antioxidants and vitamins A, C, D, and E) from the seeds, Seed cold-presses them to extract the good-for-your-skin oils inside. Macaela Mackenzie, Allure, "L'Oréal Is Launching Seed Phytonutrients, a Sustainable Beauty Brand With Paper Packaging," 20 Apr. 2018 Mangoes also provide a hefty dose of vitamin A (critical for healthy vision) and folate. Darlene Zimmerman, Detroit Free Press, "Mango gazpacho is a sweet spin on a classic summer soup," 17 June 2018 For example, the use of vitamin A or vitamin E supplements while taking blood thinners may increase the risk of bleeding. Ronald S. Litman,, "New study on supplemental vitamins proves they're useless and a waste of money," 5 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'vitamin A.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of vitamin A

circa 1920, in the meaning defined above

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Statistics for vitamin A

Last Updated

13 Sep 2018

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Time Traveler for vitamin A

The first known use of vitamin A was circa 1920

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More Definitions for vitamin A

vitamin A


Medical Definition of vitamin A 

: any of several fat-soluble vitamins or a mixture of two or more of them whose lack in the animal body causes keratinization of epithelial tissues (as in the eye with resulting night blindness and xerophthalmia): as

a : a pale yellow crystalline highly unsaturated alicyclic alcohol C20H29OH that is found in animal products (as egg yolk, milk, and butter) and especially in marine fish-liver oils (as of cod, halibut, and shark) and that is used in various forms in medicine and nutrition

called also retinol, vitamin A1

b : a yellow viscous liquid alicyclic alcohol C20H27OH that contains one more double bond in a molecule than vitamin A1 and is less active biologically in mammals and that occurs especially in the liver oil of freshwater fish

called also vitamin A2

Comments on vitamin A

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not any or not one

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