Lactose Intolerance

Lactose intolerance (or hypolactasia) is the condition in which lactase, an enzyme needed for proper metabolization of lactose (a sugar that is a constituent of milk and other dairy products), is not produced in adulthood. A lactose tolerance test, a hydrogen breath test, or a stool acidity test is required for a clinical diagnosis.[1]

Lactose intolerance can sometimes be confused with milk allergy. In reality, the former is a lack of the enzyme lactase, while the latter is an aberrant immune response (usually) to milk proteins.

With lactose intolerance, the result of consuming too much lactose is excess gas production, stomach aches and often diarrhea. Most lactose-intolerant adults can drink about 250 mL (8 oz) of milk per day without severe symptoms

Since the majority of northern Europeans and some Mediterranean Europeans have the mutation rendering them lactose-tolerant, lactose intolerance is widelySince the majority of northern Europeans and some Mediterranean 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 grams of lactose (in a solution with water) are swallowed. If the lactose cannot be digested, enteric bacteria 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.

Measuring the blood glucose level every 10–15 minutes after ingestion will show a "flat curve" in individuals with lactose malabsorption, while the lactase persistent will have a significant "top", with an elevation of typically 50–100% within 1–2 hours.

A fecal pH test can be used clinically to detect the acids created by intestinal bacteria that consume undigested lactose.

A definitive diagnosis for research purposes can be obtained by analysis of an intestinal biopsy for lactase activity.

A less precise test of lactose intolerance can be done on someone by having the person follow these steps:

1. Drink two cups of milk on an empty stomach and watching for signs of intestinal discomfort over the next several hours.

2. The following day, eat 60 g (two ounces) of hard cheese or drink two cups of lactose-free milk.

If symptoms are experienced only on the first day, the person being tested may be lactose-intolerant. If symptoms are experienced on both days, the person may have an allergy to dairy products, which is unrelated to lactose intolerance.

Some individuals are able to self-diagnose without intentionally testing themselves, simply by realizing in retrospect that their symptoms always correspond to prior lactose consumption. This, however, is the least reliable of the methods herein described, as people's memories are imperfect. In addition, it is harder to isolate one definite cause without a formal test.

There is no "cure" to lactose intolerance. Some individuals have reported their sensitivity to have decreased over time; this has not been subjected to long-term controlled study, however, and whether it is a case of desensitization remains to be seen. It should be remembered that lactose intolerance is not a binary (all-or-nothing) condition: the reduction in lactase production, and hence, amount of lactose that can be tolerated varies from person to person, and may change with age. Since lactose intolerance poses no further threat to a patient's health, managing the condition consists in minimizing the occurrence and severity of symptoms through restriction of lactose consumption.

Source: Lactose intolerance