If you have problems digesting milk or milk products, you may be deficient in lactase. Lactose is the sugar in cow's milk and milk products, while lactase is the gastrointestinal enzyme needed for its breakdown and absorption. Although distinct in their properties and origin, how lactose and lactase interact in your gastrointestinal system is pertinent.
Lactose is a Disaccharide Sugar
Lactose is a type of carbohydrate called a disaccharide sugar. Disaccharides consist of two simple sugars linked together. Lactose is made up of the simple sugars glucose and galactose. Lactose is found in nature only in animal sources. While lactose is most commonly associated with cow's milk, lactose is formed in the lacteal glands of all milk producing mammals including goats, pigs, sheep, and lactating women.
Lactose Content is Variable
Lactose content in mammalian milk ranges from 1 percent to nearly 13 percent. Human milk contains about 9 percent lactose, making it the sweetest milk. Lactose makes up approximately 4.7 percent of cow's milk and is responsible for its sweetness. Eight ounces of milk contains 12 g of lactose, which provides 48 of the calories contained in it regardless of whether its skim, low-fat, or whole milk.
Lactase Breaks Down Lactose
Lactase is an enzyme secreted by villi in the small intestine needed to breakdown lactose into galactose and glucose; disaccharides cannot be absorbed intact in the small intestine. Lactase is made and secreted in response to lactose ingestion. Since milk consumption decreases as we age, so does lactase production.
Lactose Intolerance is Manageable
A deficiency of lactase in the digestive tract is called lactose intolerance. Symptoms of lactose intolerance include flatulence, stomach cramping, nausea, and diarrhea that occur approximately 30 minutes to 2 hours after ingestion of lactose. If you are lactose intolerant, taking an over-the-counter lactase supplement just prior to meals containing lactose and using lactose-free milk are options will allow consumption of milk and milk products.
References
- "Pathophysiology of the Digestive System"; Richard Bowen, PhD, DVM, et al; 2006
- "A Handbook of Sugar Analysis: a Practical and Descriptive Treatise for Use in Research, Technical and Control Laboratories"; Charles Albert Browne; 1912
- "Gastroenterology"; The Genetically Programmed Down-regulation of Lactase in Children; Wang, et al; June 1998
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