What Is Lactose Intolerance?

Most reactions to milk, particularly those that occur primarily in the gastrointestinal tract, are not allergic in nature. The most common adverse reaction to milk, which usually starts around age 7 or 8 years, is lactose intolerance. Symptoms of lactose intolerance, which include abdominal cramping, gassiness, nausea, and diarrhea, occur between 30 minutes to 2 hours after con-suming milk products. Lactose intolerance is caused by an inability to digest significant amounts of lactose, which is the major sugar found in milk.

Lactose intolerance is caused by a shortage of the enzyme lactase, which is produced by cells in the small intestine. Some people who are deficient in lactase do not have symp-toms of lactose intolerance unless they eat very large amounts of dairy-containing foods. Patients who develop lactose intolerance early in life are considered to have a “primary” lactase deficiency. Older patients with chronic digestive diseases, such as ulcerative colitis, may also develop lactose intolerance. These patients are considered to have a “secondary” lactase deficiency.

Up to 15% of all Americans are lactose intolerant, while the figure rises to 80% in African Americans, 80% in Native Americans, and 90% in Asian Americans. Pre-mature babies may also be lactose intolerant, as lactase does not increase to full levels until the last trimester of pregnancy. Lactose intolerance may be difficult to diagnose based on symptoms alone, and the first step often taken by a physician is to eliminate all cow-based dairy products from the diet to see if the symptoms go away. The most common diagnostic test used to confirm questionable cases of lactose intolerance is the hydrogen breath test, which may be ordered by a doctor in confusing cases.

Janet’s comment:

I had a really bad stomach infection after a trip to Mexico last summer. I ate food from some small stands, and later that night I had diarrhea and cramps. I was sick for about a week and saw my doctor.

She gave me Cipro to take for a few days, and I felt better. After that, I noticed that whenever I ate a lot of cheese or had cereal and milk, I started cramping again and my stools were loose. After a couple of weeks of this, I went back to my doctor, and she suspected that the gastrointestinal infection had caused me to become temporarily lactose intolerant. I’ve been avoiding all dairy for the past month, without any more stomach symptoms, and my doctor said she believed that, over the next few months, I should go back to normal and be able to have dairy again.

Lactose  intolerance

Inability to digest  lactose, which is a principal sugar of milk, which causes symptoms of diarrhea, abdominal pain, and bloating.