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β-d-galactosidase; an enzyme in the intestinal mucosa that hydrolyzes lactose, producing glucose and galactose.
lactase deficiency a deficiency of intestinal lactase, which causes abdominal distention and cramping and often diarrhea when milk is drunk. The condition is usually hereditary with an onset between infancy and early adulthood, and is more common in Blacks, American Indians, and East Asians (70 to 90 per cent) than in Whites (10 to 15 per cent). It may also occur secondary to massive small bowel resection or to diseases involving the mucosa, such as celiac disease, Crohn's disease, tropical sprue, and ulcerative colitis.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
lactose intoleranceA term that encompasses an array of adverse responses to consumption of non-human milk, in particular the inability to digest lactose, a sugar in milk and many dairy products. Up to 75% of adults have a decrease in lactase with age, which presents clinically as abdominal bloating, cramps, flatulence, diarrhea, nausea and/or vomiting, and borborygmi (a rumbling noise of the intestines).
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.