©2000 by Jerry Sobieraj, MD
Lactose is a sugar found in milk and milk products. It is actually composed of two simpler sugars, glucose and galactose. Appropriate digestion of this sugar requires your body being able to break down lactose into the two simpler sugars.
You probably lack the enzyme lactase, which is used by the body to digests lactose. Some people totally lack this enzyme, whereas others are only partially deficient. If you lack the enzyme lactase, you will be unable to digest lactose properly. People of northern European ancestry are most likely to have functioning lactase. As one moves south toward the Mediterranean and Africa, the incidence of lactose intolerance increases up to 90%.
When you do not digest lactose properly, the bacteria in your intestine finish the job. This may result in excessive rectal gas (i.e. flatulence), bloating, abdominal cramps, and even diarrhea. Usually the relationship between these symptoms and milk products is easily established. If not a breath test may be done to confirm the diagnosis.
Milk products which have had their lactose digested by bacteria are less likely to cause symptoms in people with lactose intolerance. The following foods are generally well tolerated:
Theses foods will still have small amounts of lactose in them. If you cannot tolerate these, you are likely to have no functioning lactase in your small intestine. Thus, you will need to be very careful when evaluating foods which may contain even small amounts of milk products.
Most milk products will contain substantial amounts of lactose. The following foods should generally be avoided:
Theses foods generally contain substantial amounts of lactose. Very small quantities may be tolerated, especially, if not taken on an empty stomach.
Also, diarrheal illnesses may cause the lining of the intestine to temporarily lose the lactase enzyme. It may take 3 days after resolution of the illness for the lining of the intestine to recover. Thus, special care must be taken when lactose containing products are consumed in this situation.
Milk products may have the amount of lactose they contain decreased by using lactase drops or by taking lactase tablets prior to eating milk products. A common brand is Lact-Aid, which comes as a liquid or tablets. It is important to follow the directions on the label carefully to ensure adequate digestion of lactose. Treating milk with lactase does not affect the vitamin or mineral content of the milk.
Sometimes people find that the small amounts of lactose in baked goods is not bothersome. Also, milk is less likely to cause symptoms if consumed with other foods than on an empty stomach. eating milk does not change the lactose content of milk. People with lactose intolerance can still get adequate calcium in their diet by consuming yogurt and hard cheeses. One needs to be careful with hard cheese, as the fat content can add up quickly.