dairy aisle

—Yayra G., Saint Mary’s University, Nova Scotia

What is lactose intolerance?

Let’s first talk about what lactose intolerance means. Lactose is a sugar contained in milk products. It can’t be absorbed from your bowel without first being broken down into smaller molecules. This is done by an enzyme called lactase. People who are lactose intolerant don’t produce enough of this enzyme to break down the lactose.

If you are lactose intolerant, you may experience the following symptoms soon after eating milk products:

  • Abdominal cramps
  • Gas
  • Diarrhea

Why are some people lactose intolerant?


One reason for the lack of lactase is due to genetic or familial factors. When this is genetic, using milk substitutes or using lactase tablets may help.

Infections or diseases

Other people can develop lactose intolerance because the inner lining of the small intestine is inflamed and not working at its best.

This happens with:

  • Infections
  • Giardia (a parasite sometimes found in water or on infected surfaces)
  • Certain conditions, such as Crohn’s disease

People with these conditions may regain their tolerance for lactose over time.

Sometimes an overgrowth of bacteria in the small intestine can cause lactose intolerance. In this case, probiotics may be useful to re-establish the bowel’s ecosystem and get things working normally.

Solutions and substitutes

Lactose intolerance can be a frustrating condition. If you avoid all milk products, be aware of the risk of deficiencies in calcium and Vitamin D. You may use substitutes such as enriched soy milk, almond milk, or coconut milk.  If you are worried about your diet, talk to a health care provider about what you can safely eat.

More on lactose