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Lactase persistence or lactose tolerance is the continued activity of the lactase enzyme in adulthood, allowing the digestion of lactose in milk.In most mammals, the activity of the enzyme is dramatically reduced after weaning. [1]
The majority of humans actually follow this protocol as well, and down-regulate lactase production around 3-5 years of age. Interestingly, though, the majority of caucasians, mainly those from northern european background, continue to have elevated lactase activity all the way into adulthood, and so they exhibit “lactase persistence”.
Lactase activity persistence in adults is associated with two polymorphisms: C/T 13910 and G/A 22018 located in the MCM6 gene. [28] These polymorphisms may be detected by molecular biology techniques at the DNA extracted from blood or saliva samples; genetic kits specific for this diagnosis are available.
Lactase persistence One of the best known examples is the prevalence of the genotype for adult lactose absorption in human populations, such as Northern Europeans and some African societies, with a long history of raising cattle for milk.
Lactase is an enzyme that some people are unable to produce in their small intestine. [2] Technology to produce lactose-free milk, ice cream, and yogurt was developed by the USDA Agricultural Research Service in 1985. [3]
Many adult humans lack the lactase enzyme, which has the same function as β-galactosidase, so they are not able to properly digest dairy products. β-Galactose is used in such dairy products as yogurt, sour cream, and some cheeses which are treated with the enzyme to break down any lactose before human consumption. In recent years, β ...
Lactase persistence [ edit ] In one study, five ancient DNA samples from Yamnaya sites had a frequency of over 25% of an allele that is associated with lactase persistence , conferring lactose tolerance into adulthood . [ 45 ]
Lactose, or milk sugar, is a disaccharide composed of galactose and glucose and has the molecular formula C 12 H 22 O 11.Lactose makes up around 2–8% of milk (by mass). The name comes from lact (gen. lactis), the Latin word for milk, plus the suffix -ose used to name sugars.