What does lactase mean?
Lactase is an enzyme made in the small intestine that helps digest lactose, the natural sugar in milk. It splits lactose into the simpler sugars glucose and galactose, which the body can absorb and use for energy. Most people produce plenty of lactase throughout life, but some have reduced lactase activity, a condition commonly called lactase deficiency. In these individuals, lactose may remain partly undigested in the intestine and cause symptoms such as gas, bloating, cramps, or diarrhoea after eating dairy products. The word also appears in discussions of genetics because the persistence of lactase production into adulthood varies among populations. Outside the body, lactase occurs naturally in some microorganisms and can be used in food production to modify the lactose content of dairy products. Its importance is both practical and biological: it links a single enzyme with digestion, food tolerance, and human population history.
nounAn enzyme that breaks down the milk sugar lactose into simpler sugars, chiefly glucose and galactose. It is produced in the small intestine and is also found in certain bacteria and other organisms.
- An enzyme that hydrolyses lactose into glucose and galactose.
"People with lactase deficiency may experience discomfort after consuming dairy products because their bodies produce too little lactase to digest lactose efficiently."
"Infants produce abundant lactase, allowing them to digest the lactose in their mother's milk."
"Researchers studied lactase activity in intestinal samples to investigate the cause of persistent digestive discomfort."
The plural is uncommon; the singular lactase is normally used for the enzyme in general.
"The study compared lactases produced by different bacterial strains."
Lactase is the tiny biological helper that can determine whether milk feels comfortable—or troublesome—for the person drinking it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does lactase come from?
The word is formed from the combining form lact-, associated with milk, together with the suffix -ase, used in biochemical nomenclature to indicate an enzyme. Its underlying roots are Latin, with related English words such as lactation, lactic, and lactose reflecting the Latin elements lac and lact-, meaning milk. The development of the modern term followed the growth of scientific biochemistry and the identification of specific enzymes that act on particular substances.
Related word forms
How lactase is actually used
Lactase is primarily used in biology, medicine, nutrition, and food science. In genetics and population history, lactase persistence refers to the continued production of lactase into adulthood; this describes the trait rather than a separate sense of the enzyme itself.
Easily confused with lactase
Lactase is the enzyme that digests lactose, the sugar itself found in milk.