FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

"RUMBLING INTESTINES" CAN MEAN LACTOSE INTOLERANCE

Question: I've had some trouble with gas and bloating and wondered if this results from drinking milk. I've seen advertisements for Lactaid and similar milk products that claim to reduce or eliminate the problem. How does one determine if she can't digest milk?

Answer: Milk is a complex food that contains water, protein, fat, sugars, and other things in lesser amounts. It is an excellent food source. In fact, it is the best food source for babies that is why mothers make it.

In order to benefit from milk, it must be digested. The subtle differences between the proteins in cows' milk and those in human milk can present problems. That is why babies should be breast fed (human milk with human proteins) or take special baby formula rather than cows' milk.

The sugar in cows' milk, called lactose, is a common cause of digestive troubles in adults. In order to nourish the body, the lactose sugar must be broken down into small pieces called "monosaccharides" before they can be absorbed into the blood stream. Some time between the age of 3 and 14, however, 75 percent of us lose the ability to make the lactase enzyme that breaks down lactose. Therefore, we no longer can convert the lactose in cows' milk into a sugar our bodies can use. Because of this, any lactose that is consumed will pass on through the intestine without being digested.

The undigested lactose within the intestine causes digestive problems in two ways. First, the body shifts water into the intestine to decrease the lactose's concentration. The amount of lactose in one cup of milk causes about two quarts of additional water to shift into the colon. This extra water causes the intestine to churn and move food residue rapidly along its path. This is the same effect laxatives like Peptobismol have. As a consequence of this, people with lactose intolerance usually have a loud churning digestive system and also have frequent loose bowel movements.

The second symptom of lactose intolerance results from that undigested lactose passing through the small intestine into the colon. The colon is home to billions of bacteria, some of whom can use this lactose as food. The important waste product from the bacterial metabolism of lactose is hydrogen gas. In fact, this happens so efficiently that the lactose in one cup of milk can make one gallon of hydrogen gas. No wonder people with this problem often complain of marked increase in intestinal gas!

So, to more directly answer your question, you can be suspicious that you suffer from lactose intolerance if you are an adult who has frequent loud rumbling digestive noises along with lose stools, bloating and much intestinal gas.

The diagnosis can be confirmed by either of two methods. A minor surgical procedure can be done to remove a small sample of the small intestine's lining to test for the presence of the lactase enzyme, but this is rarely necessary. A more practical method is to consume a fair amount of lactose, usually 50 grams, and watch for symptoms of lactose intolerance. If they are present, then the person has it.

The problems of lactose intolerance can be avoided by simply avoiding lactose. In other words, no milk or milk products. Some individuals are fairly comfortable if they restrict the amount of lactose they consume instead of totally eliminating it. Lactaid milk and other similar products usually cause few problems because they have been treated with the lactase enzyme to reduce but not totally eliminate the amount of lactose that is present. The bacterial action that changes milk into cheese and yogurt uses up some of the lactose, so these products may be tolerated without causing severe symptoms. Milk and cottage cheese, on the other hand, will certainly cause trouble for someone with lactose intolerance.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.