lactose intolerance

Lactose intolerance is an inherited condition in which levels of the enzyme lactase are not sufficient to totally digest the amount of lactose (milk sugar) in the diet. Because the dietary lactose is not digested normally in the small intestine, it passes through into the lower bowel where certain bacteria which are normally present digest it. The biproducts of this bacterial digestion of the sugar are chiefly gaseous. The sugar itself attracts water into the colon and acts as a laxative; thus the main symptoms noticed by lactose intolerant persons are diarrhea, bloating and crampy gas.

Babies are born with low levels of intestinal lactase, and they often go through a phase of watery transitional stools on the second or third day of life. This is because the enzyme is "induced," that is it is "turned on" by the presence of lactose in the gut. But this is temporary - it lasts a day or two and then the stools firm up.

This condition is rarely a problem in the very young, but in some persons, more frequently of African-American descent, by two or three years of age the condition begins to be troublesome. Treatment involves avoidance of excessive amounts of dairy products, but patients can also help themselves by taking an enzyme preparation (Lactaid®)that substitutes for the enzyme they lack.

There is a milk-based formula, Lactofree®, from which the lactose has been removed. It is designed to aid lactose intolerant infants. Because lactose is the natural sugar of breast milk, these infants seem to be rare. I for one have trouble imagining Nature being so capricious as to have babies born unable to digest their own mothers' milk.

Lactose intolerance is often diagnosed when the baby has some problems, is switched to lactose-free formula, and is then thought to be "cured" of the problems. We call this a therapeutic challenge, and congratulate ouselves. But the baby may have had a totally unrelated problem and just seemed to get better at about the same time. The actual way to diagnose lactose intolerance is something called a breath hydrogen test. I can't say I've ever heard of a young infant given one of those to diagnose lactose intolerance, so I remain moderately skeptical (but always open-minded) about this diagnosis in the very young.

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