Lactose intolerance is the condition (found in the majority of humans) in which lactase, an enzyme needed for proper metabolization of lactose (a constituent of milk and other dairy products), is not produced in adulthood. With lactose intolerance, the result of consuming lactose or a lactose-containing food is excess gas production and often diarrhea. In western cultures milk products are nearly ubiquitous and are contained in at least a small amount in almost all recipes, restaurant dishes, and processed food. People with lactose intolerance need to be very careful reading food ingredient labels if they wish to avoid consuming lactose.
lactose intolerance symptoms
Without lactase, the lactose in milk remains uncleaved and unabsorbed. Lactose cannot pass easily through the intestinal wall into the bloodstream, so it remains in the intestines. Soon, gut bacteria adapt to the relative abundance of lactose (relative to other sugars like glucose) and switch over to metabolizing lactose. So where are the symptoms of lactose intolerance? Along the way the bacteria produce copious amounts of gas by fermentation.
The gas causes a range of unpleasant abdominal symptoms, including stomach cramps, flatulence and diarrhea. Like other unabsorbed sugars, e.g. mannitol, the lactose raises the osmotic pressure of the colon contents, preventing the colon from resorbing water and hence causing a laxative effect to add to the excessive gas production.
treating lactose intolerance and it's symptoms
One solution to this problem (other than avoiding milk) is lactose-free milk, which is produced by passing milk over lactase enzyme bound to an inert carrier: once the molecule is cleaved, there are no lactose ill-effects, whatever the milk drinker's ancestry. The milk sold for pet cats is another example of lactose-reduced milk. Oddly, many European cat breeds have a mutation similar to the human mutation, also prevalent in Europe, which allows symptom-free adult lactose consumption. Most oriental breeds are particularly sensitive to lactose.
In recent years (1990–2000) there has been an increase in the number of lactose-reduced and lactose-free dairy products. Examples of these products are cottage cheese, American cheese and ice cream. These products are made using milk substitutes such as soy milk, almond milk, or rice milk. Another recent solution has been a pill which artificially provides the missing enzyme, allowing a person to tolerate milk products for a period of a few hours after taking the pill.
diagnosis of lactose intolerance
Since the majority of Europeans have the mutation rendering them lactose-tolerant, lactose intolerance is widely regarded as a medical condition in Europe and North America. A fair proportion of patients with symptoms of irritable bowel syndrome actually have lactose intolerance without knowing it.
A simple test can clarify the issue: after an overnight fast, 50 gram of lactose (in a solution with water) is to be swallowed. If the lactose cannot be digested, enteric bacteria will metabolize it and produce hydrogen. This can be detected in the air the patient exhales. The test takes about 2 to 3 hours. A medical condition with similar symptoms is fructose malabsorption.
Posted by Staff at May 18, 2005 1:18 AMblog comments powered by Disqus