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Lactose intolerance

Lactose intolerance describes a condition in which some people’s bodies are unable to digest the lactose in dairy products.

A woman with a glass of milk, holding her stomach

Milk contains a type of sugar known as lactose. During the digestive process, the small intestine produces an enzyme called lactase, which is responsible for breaking down lactose. In people with lactose intolerance, insufficient lactase is produced to perform this function, leaving the unabsorbed lactose to move into the colon. 

Here lactose intolerance causes its host of uncomfortable symptoms as normal gut bacteria ferment the lactose. It’s normal for lactase production to decrease after infancy when we no longer rely on breast milk for nutrition but in some individuals it falls off so sharply that dairy products become difficult to digest. Known as primary lactose intolerance, this is determined by genetics. 

Secondary lactose intolerance can occur after disease or injury to the small intestine.

What are its symptoms?

Symptoms and signs of lactose intolerance usually come on 30 minutes to two hours after consumption of dairy products and include:

  • Bloating
  • Diarrhoea
  • Nausea (and in some cases, vomiting)
  • Stomach rumbling
  • Abdominal cramping
  • Flatulence

The severity of the symptoms will correlate with how much lactose has been consumed. Small amounts of lactose may not cause symptoms at all in some lactose intolerant individuals.

How is it diagnosed? 

There are numerous tests that can confirm a diagnosis of lactose intolerance. Two tests will require you to drink a liquid high in lactose. The lactose tolerance test measures the amount of glucose present in the blood after two hours – if it doesn’t rise, it suggests your body isn’t digesting lactose adequately. 

The other test, the hydrogen breath test, looks for a higher percentage of exhaled hydrogen than normal – a sign that lactose isn’t being broken down in the small intestine and that fermentation of lactose in the colon is releasing hydrogen. 

A stool acidity test can also be an indicator that lactose is fermenting in the colon.

What are your treatment options? 

It is currently not possible to boost lactase production, meaning that there is no cure for lactose intolerance. As such, lactose intolerance treatment is focused on avoiding lactose-containing products. 

It’s worth noting that some dairy products contain much less lactose than others per serving. Processing of certain foodstuffs can reduce lactose content. For example, butter, Cheddar cheese and cream cheese all contain 0.1g or less of lactose per portion compared to roughly 12g per 250ml glass of milk or 9g in 200g plain full-cream yoghurt. How much lactose an individual can handle will vary from person to person. 

Lactase enzyme pills or drops can be taken to help ease digestion of dairy products.

Can it be prevented?

Lactose intolerance cannot be prevented but the symptoms can be avoided by sticking to a diet relatively free of any lactose-containing products.

IMAGE CREDIT: 123rf.com

The accuracy of this information was checked and approved by physician Dr Thomas Blake in July 2016