Family doctor

Overview:

• Lactose intolerance is a problem digesting products which contain sugar in milk
• The condition is due to a lack of the enzyme lactase which breaks down lactose
• Some patients can tolerate higher levels of lactose than others
• The problem is more common among certain ethnic groups
• Symptoms include stomach cramps, bloating, wind and diarrhoea
• Diagnosis includes a lactose tolerance test and a hydrogen breath test
• Treatment involves reducing the amount of lactose eaten to comfortable levels

What is it?

Lactose intolerance is a problem with digesting certain amounts of dairy products.

Lactose is the sugar found in milk and those with lactose intolerance have a shortage of the enzyme "lactase" which breaks down lactose in dairy foods.

Some patients can tolerant larger amounts of lactose than others, probably due to larger quantities of the enzyme lactase. However, not all people with a lack of lactase are lactose intolerant.

Some children are born without an ability to produce lactase and are termed "lactase deficient", but this is a rare condition. These children should eat nothing that contains lactose.

Lactose intolerance is more common among ethnic groups and is less likely among Caucasians.

Most sufferers become lactose intolerant as they get older. The condition is quite common but does not pose a serious health threat.

What are the symptoms?

The main symptoms include stomach cramps, wind, bloating, nausea and bouts of diarrhoea.

The diarrhoea usually begins up to 2 hours after eating dairy products.

The condition is normally diagnosed with a lactose tolerance test, a hydrogen breath test, and test for stool acidity.

The lactose tolerance test involves the patient not eating prior to the test and then drinking a liquid containing lactose. The patient's blood glucose is measured in the following two hours to assess how the person is digesting the lactose.

The hydrogen breath test measures the level of hydrogen on a patient's breath after drinking a lactose drink. High levels of hydrogen indicate lactose intolerance. This is due to larger amounts of this gas being produced in the bowel because of a failure of the digestive system to break down lactose.

The stool acidity test is mainly used for infants whose samples can indicate the presence of undigested lactose.

What can be done to help?

There is no cure for lactose intolerance but symptoms can be controlled by a special diet.

The amount of lactose an individual can tolerant varies from person to person. For example, some patients may suffer symptoms after just a small glass of milk while others may be able to safely drink a large glass. It is up to each individual to decide how much they can handle, and this is usually achieved by testing what levels of lactose cause symptoms.

Infants and young children who show signs of lactose intolerance are advised to change from cow's milk formula to soy formula.

Lactase enzymes are available and can be added to glasses of milk to reduce the lactose content by about 70 percent. Chewable lactase enzyme tablets have also been developed to assist with digestion of lactose in dairy products.

Limiting the intake of dairy foods can lead to a reduction in calcium which is needed for bone density and to help lower the risk of osteoporosis. Fortunately many non-diary products are high in calcium. These include:

• Fish with soft bones such as salmon
• Broccoli
• Bok choy
• Kale
• Turnip greens
• Oysters
• Sardines
• Shrimps
• Molasses
• Tofu

Some sufferers may be able to tolerant yoghurt despite its high lactose levels. Research shows yoghurt contains some of the lactase enzyme needed to aid digestion of the milk sugar.

Hidden sources of lactose:

People with lactose intolerance are advised to carefully read food labels to check for diary additives. Beware of foods which contain milk powder, non-fat milk powder, milk solids, whey and curds.

Some foods which may contain small amounts of lactose include:

• Breads and other bakery foods
• Breakfast cereals
• Margarine
• Salad dressings
• Processed meats
• Lollies and sweets
• Pancake and cake mixes

Some medicines also contain lactose as a base for some drug tablets, but these only need to be avoided by those with severe conditions.

Getting help

People who suspect they are lactose intolerant should not restrict their diet without a specific diagnosis. See your doctor to discuss your symptoms and possible further tests .