Lactose intolerance develops when the body can't properly process a sugar in milk and other dairy products called lactose. People who have this disorder have insufficient internal supplies of an enzyme called lactase. Whey protein is a collective term used to describe a number of proteins in dairy products. Consuming these proteins does not trigger lactose intolerance.
Lactose and Lactase
Lactose is the main sugar in breast milk and cow's milk, and accounts for roughly 4.7 percent of cow's milk's overall content. Each unit of this sugar is made from the combination of a single molecule of the sugar called glucose and a single molecule of the sugar called galactose. Lactase enzymes break down units of lactose by breaking apart the chemical bonds that link glucose and galactose. This enzymatic action must occur before humans can fully or properly digest any lactose-containing product.
Lactose Intolerance Causes
Lactose intolerance occurs when lactose does not get broken down during digestion, and instead gets fermented by intestinal bacteria. It differs from a milk allergy, which occurs when your immune system mistakenly identifies dairy products as unwanted foreign intruders. In people who have a condition called primary lactase deficiency, normal lactase production begins to drop at around age 2, although symptoms of lactose intolerance --- such as diarrhea, gas and abdominal pain and bloating --- typically don't appear until later childhood or adulthood. In people with a condition called secondary lactase deficiency, injuries to the small intestine trigger lactase decreases and subsequent intolerance symptoms. Potential sources of these injuries include Crohn's disease, severe diarrhea, chemotherapy and celiac disease.
Understanding Whey Protein
The main milk proteins are substances called caseins. Other proteins in milk include alpha-lactalbumin and beta-lactoglobulin. During cheese production, caseins get separated from the liquid content of milk, commonly referred to as whey, which contains water, lactose, alpha-lactalbumin, beta-lactoglobulin and any other noncasein protein. These separated noncasein proteins are known collectively as whey protein. In addition to its protein content, whey protein typically contains milk components such as hormones, enzymes and substances called nutrient transporters and growth factors.
Considerations
As a sugar, lactose belongs to a class of substances called carbohydrates. By definition, whey protein belongs to a class of substances called proteins. Inability to digest whey protein will result in protein intolerance, not lactose intolerance. Still, since both lactose and whey protein are common components of liquid whey, people with lactose intolerance typically need to reduce their consumption of products labeled as "whey." Consult your doctor for more information on the causes of lactose intolerance, as well as information whey protein and protein intolerance.
References
- National Digestive Diseases Information Clearinghouse; Lactose Intolerance; June 2009
- University of Georgia -- University Health Center: Lactose Intolerance
- University of Illinois: Milk Composition; Proteins
- Biology Online: Lactose
- Biology Online: Lactase
- MayoClinic.com; Milk Allergy (Pages 1 and 2); August 11, 2011
