The Connection between IBS and Lactose Intolerance

Written by: Truc Thanh | Last reviewed: June 2016. | Last updated: June 2017

What is lactose intolerance?

Lactose intolerance is due to the decreased activity of lactase, which is present in the body to break down lactose found in dairy products. Lactase activity starts to decrease within the first few months of a person’s life. Approximately 70% of the adult population has a decreased lactase activity. These people have a lactase deficiency in which lactose is not properly absorbed by the body, but passes through the gastrointestinal tract causing gastrointestinal symptoms.1

The most common symptoms include:2

Less common symptoms:3

  • Nausea
  • Constipation
  • Headaches
  • Fatigue
  • Loss of concentration
  • Muscle and joint pain
  • Mouth ulcers
  • Urinary difficulties

It should be noted that the less common symptoms may also be due to the presence of related functional diseases, such as IBS.3 Dietary intolerances, particularly lactose, are found in 33% of people with IBS.4

What foods lead to lactose intolerance?

Consuming milk and dairy products are troublesome for people with lactose intolerance. These food products may include:2

  • Milk (sourced from cows, goats, or sheep)
  • Ice cream
  • Yogurt
  • Soft cheeses

Treatments or alternative foods

Treatment of lactose intolerance may include lactose-reduced food items and enzyme replacement. For people with an intolerance to fermentable oligo-, di-, monosaccharides and polyols (FODMAPS), which includes lactose, the treatment may include a low FODMAP diet. FODMAP intolerance is present in at least half of people with IBS.3

People with lactose intolerance may find that changing their diet may improve symptoms. Some of these alternative food items include:1

  • Lactose free milk or rice milk
  • Hard cheeses, like camembert
  • Lactose-free yogurt
  • Gelati or sorbet
  • Butter

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