lac·​tase | \ ˈlak-ˌtās How to pronounce lactase (audio) , -ˌtāz \

Definition of lactase

: an enzyme that hydrolyzes beta-galactosides (such as lactose) and occurs especially in the intestines of young mammals and in yeasts

Examples of lactase in a Sentence

Recent Examples on the Web The firm won an Accelerator grant to develop a subcutaneous sensor to simultaneously monitor glucose, ketones, and lactase in diabetic patients. Nicholas Wallace, Science | AAAS, "Watch out Silicon Valley: European Union gets into the venture capital game," 8 Apr. 2020 These individuals lack the enzyme lactase (to varying degrees) that allows them to break down lactose, the sugar in milk. Sara Chodosh, Popular Science, "Half of the people who think they have food allergies actually don’t," 7 Jan. 2019 Lola’s genome also contained alleles that are usually associated with the inability to produce lactase—an enzyme that’s important in digesting milk—as an adult. Kiona N. Smith, Ars Technica, "Ancient “chewing gum” contains a 5,700-year-old genome," 13 Feb. 2020 That means your body lacks the enzyme lactase, which breaks down lactose, the sugar found in dairy products, Michael Nusbaum, MD, bariatric surgeon and founder of Healthy Weight Loss Centers, tells Health. Samantha Lauriello,, "10 Things That Cause Belly Bloat, and How to Prevent Them," 20 Nov. 2019 More than 90% of China’s population is deficient in lactase, the enzyme that breaks down the milk sugar lactose in the gut, per a 1984 study. Eamon Barrett, Fortune, "How Oatly Plans to Quench China’s Thirst for Milk," 23 July 2019 June 12, 201700:59 Lactose is a naturally occurring sugar in milk that can cause digestive issues like gas and bloating for people who lack the enzyme (lactase) to digest it. NBC News, "Dr. Fernstrom: What's the best milk alternative for YOUR lifestyle?," 17 July 2019 The spread of that culture had the effect of spreading the lactase persistence gene. Quanta Magazine, "Finding the Actions That Alter Evolution," 5 Jan. 2017 Drinking milk after your lactase gene is turned off is no fun. Bob Gathany,, "Up in the air at the Huntsville Community Kite Festival," 4 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lactase.' 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 lactase

1891, in the meaning defined above

History and Etymology for lactase

International Scientific Vocabulary

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Time Traveler for lactase

Time Traveler

The first known use of lactase was in 1891

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Cite this Entry

“Lactase.” Dictionary, Merriam-Webster, Accessed 26 Nov. 2020.

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More Definitions for lactase


lac·​tase | \ ˈlak-ˌtās, -ˌtāz How to pronounce lactase (audio) \

Medical Definition of lactase

: an enzyme that hydrolyzes especially lactose to glucose and galactose and occurs especially in the intestines of young mammals and in yeasts

More from Merriam-Webster on lactase Encyclopedia article about lactase

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