What is lactose intolerance?

Lactose intolerance is the most common of gastrointestinal problems, it is caused by the absence of the lactase gene, as a result the lactase enzyme is not produced and lactose is not broken down in the gut.

The symptoms of lactose intolerance are stomach cramps, nausea and diarrhea. Geographically lactose intolerance is most common across Asian, Mediterranean and Scandinavian populations.

The degree of lactose intolerance correlates well with the level of malabsorption, i.e. The level of Hydrogen produced in the large intestine.

Lactose is broken down into glucose and galactose. If it is not broken down, however, it moves into the large intestine (colon) and the bacteria in the colon ferment the undigested lactose releasing Hydrogen as a waste product. Hydrogen is absorbed into the bloodstream and expelled from the body via the lungs. When the lactase enzyme is missing, small amounts of lactose remain in the gut it draws water from the walls of the intestine causing them to become distorted and it is this that causes the discomfort people suffer.

Young people usually adapt to increased levels of milk and other dairy products if exposure is prolonged over a period of time, this is due to an increased tolerance of fermentation in the body, however intolerance to mothers' milk is a very common condition in the newborn.

• The patient is instructed to fast a minimum of 12 hours (usually overnight)
• A baseline breath test is then performed
• A lactose solution is then given to the patient usually containing 1 gram per kilogram of the patients bodyweight (often termed a labeled dose)*
• The patient is then asked to repeat the breath test every 30 minutes for a 3 hour period

*If we were testing for some other carbohydrate malabsorption such as sucrose or fructose intolerance, we would simply change the test substrate. In all cases, hydrogen is still the expired gas.

What is viewed as normal hydrogen breath levels?

In individuals who are being tested and as a result have fasted, the level of Hydrogen is usually below 10 ppm at the beginning of the test. Where base levels are higher this may be due to slow digesting fibers such as beans.

What are the likely responses?

Increased levels after ingestion of lactose are as follows:

20 – 40 ppm mild intolerance
40 – 80 ppm moderate intolerance
above 80 ppm severe intolerance

There are other response and time factors within the test that can be used for other diagnosis such as bacterial overgrowth (usually an elevated level 20 – 30 minutes after ingestion and then plateaus for the rest of the test period), small bowel transient times and also diseases of the small intestine but we have concerned ourselves solely with lactose intolerance in the above response guide.

What remedies are there for lactose intolerant individuals?

If an individual is found to be lactose intolerant, they are usually given one of two options or where possible if the intolerance is not too severe both. The individual is encouraged to avoid dairy products in their diet such as milk, yogurt or cheese or use an alternative such as soy milk. There are also Lactase enzyme supplements available sometimes from the pharmacist but also from health food shops in the form of tablets or drops which will help the breakdown of lactose.

The Micro H2 and HYDRA software

The Micro H2 allows simple and reliable measurements to be made of expired breath hydrogen levels. It is easy to use, removes the need for specialist training and it's portability means it can easily be used in patient wards and in different clinical settings.

The choice of collection methods – either blowing directly into the monitor through a mouthpiece or alternatively through a face mask or collection bag allows all patients to be easily tested.

Combined with the HYDRA software allowing pre-set or customizable test protocols and real time testing with prompts for when the next breath sample should be taken, graphical representation of the test and interpretation of the results, the scope for hydrogen breath testing is complete.