What is it?

Lactose intolerance is when the small intestines lack or do not have sufficient amounts of an enzyme called lactase, which breaks down lactose.

In order for lactose to be absorbed into the body, it has to be broken down into two smaller sugars — glucose and galactose.

The severity of the intolerance typically depends on the amount of lactose containing in food a person eats or drinks. Lactose intolerance does not cause damage to the gastrointestinal tract.

What is lactose?

Lactose is a form of sugar, often found in milk and milk products. It is the main carbohydrate in dairy products.

How common is it?

Lactose intolerance is very common, affecting up to 70% of people worldwide. South Koreans and Yemenis have 100% intolerance.

It is less common in Northern and Central Europe, where it is only 5%. In Uganda, some sources state it as high as 50% or even more.

Is lactose intolerance a disease?

Many genetic science sources argue that the normal state is to be intolerant.

Other mammals lose their ability to digest milk as soon as weaning occurs.  In fact, in humans, the persistence of producing lactase enzyme is due to a gene mutation.

Humans, too, should lose their ability to produce lactase a lot earlier in childhood.

The persistence of producing lactase is of many advantages as milk is a nutritious source of food, not to mention water.

Signs of lactose intolerance

Symptoms may include nausea, cramps, gas, bloating or diarrhoea, often within two hours of consuming milk or dairy products, such as cheese, yogurt, etc.

The actual problem is that the undigested lactose moves to the large bowel, where it finds some bacteria that feast on it and produce lots of gas and other chemical irritants.

What are the other problems confused with lactose intolerance?

Many people will not have the diagnosis made for many years, as they will often blame ulcers for all the stomach ills they suffer.

To make the confusion worse, whenever they take some anti-acids (often used for ulcers), they feel better, cementing further the confusion of ulcers.

The other intolerance that shares similar symptoms is wheat intolerance.  Other misdiagnoses may include irritable bowel syndrome (IBS).

How it is acquired?

There are four types of intolerance and this explains the acquisition; there is the primary type, which comes as a result of ageing, this is the commonest type.

A person who previously had no issues with milk gradually starts getting problems with it. 

Next is the secondary type, this may come as a result of an illness or injury in or to the small intestines. Injury may be a result of intestinal surgery for whatever reason.

Illness may be due to inflammation in the small bowel of known or unknown causes. The third is the intolerance you are born with, also called congenital.

The last type is one that happens in premature babies when their bowels are still too immature to produce much lactase.

How is it diagnosed?

The first step is to make sense of the complaint(s) or the pattern of symptoms, typically they occur after ingesting milk or milk products.

This may be noticed in childhood. The child may simply dislike or reject the milk without any explanation.

Sometimes the diagnosis may be missed and only discovered later in early adulthood.

The other logical test is to withdraw lactose from the diet for two weeks and if the symptoms resolve, that is further confirmation of lactose intolerance.

What lab tests are there?

There are several of these; one is the lactose tolerance test, the person is given a sweet powder of lactose and blood is drawn to test for a rise in sugar every so often (15 minutes to an hour), if the blood sugar rises rather slowly, then lactose intolerance is likely. Instead of the lactose powder, a large amount of milk may be given and followed with the blood sugar levels tests.

The other is to do a hydrogen breath test after ingestion of the lactose or milk. If positive, then lactose intolerance is likely.

When undigested lactose reaches the large bowel, the bacteria there interact with it to produce lots of gas, including hydrogen, carbon dioxide and methane.

There are also home test kits, a relatively new invention, but these are expensive (in the excess of sh300,000 per test). A blood test, too, is available in some specialised labs in Kampala.

How is it treated?

Either dairy products are avoided altogether or taken in moderation or supplement lactase tablets are used each time lactose-containing products are consumed.

For some individuals, it simply self-corrects.