Lactose intolerance

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at February 29, 2016
StartDiseasesLactose intolerance

Dairy products have a sugar known as lactose. Those who have lactose intolerance have difficulty digesting lactose, causing a range of symptoms.


Definition & Facts

Most people have an enzyme known as lactase in their digestive system that breaks down the lactose. But somebody who is lactose intolerant has a reduced amount of that enzyme, after having been weaned off breastfeeding as a child.

Approximately 25% of Americans suffer from lactose intolerance. Some ethnicities are more prone to lactose intolerance than others. 90% of individuals whose ancestors descended from East Asia are impacted by lactose intolerance.

Symptoms & Complaints

Lactose intolerance can come in varying degrees, depending on the sensitivity of the individual with lactose intolerance and depending on how much lactose the individual consumes. While these factors will certainly impact the severity and frequency of the symptoms, the symptoms are generally the same.

These symptoms usually set in pretty quickly after the individual consumes lactose. A lactose intolerant person can expect to show these symptoms as little as 30 minutes later, though some people report that symptoms arrive as much as two hours later. When the digestive system cannot break down the lactose, the body will react. An individual who lactose intolerant can expect to suffer from some or all of the following symptoms:


The small intestine produces lactase (the enzyme that breaks down lactose in the digestive system). Doctors report that some patients do not produce as much lactase as they need. Some produce very little. This makes the difference between an individual with a severe case of lactose intolerance and a mild case of lactose intolerance.

The severity of an individual's lactose intolerance is inversely proportional to the production of lactase in the small intestine. So when lactose is consumed, there is not enough lactase to break it down, and the lactose will produce gas in the colon (which is why many people exhibit symptoms such as painful gas). As time passes, the small intestine will generate less lactase. This is why many will develop a case of lactose intolerance that worsens with age.

Further, if one's small intestine is injured, it might produce less lactase and result in a case of lactose intolerance. Some diseases can be the culprit of lactose intolerance. Individuals who are suffering from Crohn's disease or gastrointestinal disease might be more prone to lactose intolerance than others. These problems sometimes inhibit the small intestine's ability to produce the natural and sufficient amount of lactase.

Diagnosis & Tests

If an individual reports symptoms of lactose intolerance to their doctor, there are a number of tests that they will give the patient. The following procedures are standard approaches when testing for lactose intolerance.

  • Lactose tolerance test. If a doctor is suspicious that a patient is suffering from lactose intolerance, they will take the simple approach of assessing how the patient reacts to lactose. They will give the patient something to consume that has a measured amount of lactose (not enough to harm them) and gauge how the body reacts. If the amount of glucose in the patient's bloodstream does not increase, the doctor will deduce that the patient is not properly digesting lactose and is lactose intolerant.
  • Stool sample. Sometimes other testing methods are not available for one reason or another. When lactose does not digest properly, it is usually evident in the stool. There is lactic acid in the stood that doctors can detect and conclude that the lactose was not properly digested.
  • Hydrogen breath test. There is usually a certain amount of hydrogen on the breath. But if an individual is not digesting their lactose properly, they will exhibit greater hydrogen, providing evidence of the condition to the physicians.

Treatment & Therapy

Unfortunately, there is currently no way to increase the amount of lactase that the body produces and thus no cure for lactose intolerance. But many doctors regard awareness as excellent treatment. If the patient knows that they are lactose intolerant and they know what contains lactose, they will take the simple step of avoiding those products. If they do not consume lactose, they will not show any symptoms of lactose intolerance.

Because many people enjoy dairy products, there are so many dairy products on the market that are made without lactose for individuals who are suffering from lactose intolerance. Many people drink milk and consume other dairy products that have a reduced amount of lactose. Alternatively, there are certain products that one can add to their milk that will break down the lactose. Others who suffer from a mild case of lactose intolerance will consume it in moderation. They will have small portions of lactose so as to not activate the symptoms.

Prevention & Prophylaxis

There is currently no method of preventing lactose intolerance or lessening one's vulnerability to it. The best method is awareness of one's own capacity for lactose.