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Back to Lactose Intolerance and Milk Allergy

Prevalence of Lactose Intolerance

The true prevalence of lactose intolerance is unknown. The symptoms of lactose intolerance are highly subjective and may or may not occur among individuals with lactose malabsorption.


  • A person’s tolerance to lactose depends on a variety of factors and can change over time;
  • The prevalence of lactose intolerance is overestimated, and the true prevalence is unknown.

Most people are born with the ability to digest lactose. However, in some people, lactose intolerance can occur, whereby lactose digestion and absorption are compromised and gastrointestinal symptoms arise.

Prevalence of lactose intolerance

Many individuals mistakenly ascribe symptoms of a variety of intestinal disorders to lactose intolerance without undergoing testing.1 Yet, even in the case of lactose malabsorption, an individual may not necessarily be symptomatic. In fact, the majority of individuals who have lactose malabsorption do not have clinical lactose intolerance.2

Symptoms of lactose intolerance are highly subjective and may or may not accompany lactose malabsorption. Many factors determine whether a person who malabsorbs lactose develops gastrointestinal symptoms associated with lactose intolerance. Examples of such factors include the dose of lactose ingested, the residual intestinal lactase activity, the ingestion of other foods or nutrients together with lactose, and individual sensitivity.

Prevalence in Canada
The true prevalence of lactose intolerance is unknown. According to a national Canadian survey, the prevalence of self-reported lactose intolerance is 16%.3 However, many who self-report lactose intolerance show no evidence of lactose malabsorption as determined by objective diagnostic tests. Thus, the cause of their gastrointestinal symptoms is unlikely to be related to lactose.2

For the expert summary on this subject, consult Prevalence of Lactose Intolerance Among Canadian Adults.

Ethnicity and lactose intolerance
The prevalence of lactose intolerance and lactose malabsorption also varies across ethnic groups. It is least prevalent in European Americans, and most common in African Americans, Hispanic Americans and Asian Americans. The ethnic groups in which lactose intolerance prevalence is higher also tend to have a higher prevalence of lactase nonpersistence.2,4

Age and lactose intolerance
In general, lactose intolerance and malabsorption are not common among young children, especially those younger than 6 years.2 Some studies show that lactose malabsorption is more prevalent in children aged 10 to 16 years. However, these trends need to be verified by representative population studies using the case definition of lactose intolerance.1 Furthermore, there is little evidence that lactose intolerance increases in older individuals.


Tolerance to lactose can change over time. While the prevalence of lactose intolerance is unknown, it is uncommon among newborns and young children.

For information on management strategies for lactose intolerance, consult Lactose Intolerance: Health Authorities’ Recommendations.


  1. Zaitlin P et al. Mistaken beliefs and the facts about milk and dairy foods. Nutr Today 2013;48:135-143
  2. Suchy FJ et al. NIH Consensus Development Conference Statement: lactose intolerance and health. NIH Consens State Sci Statements 2010;27:1-27.
  3. Barr SI. Perceived lactose intolerance in adult Canadians: a national survey. Appl Physiol Nutr Metab 2013;38:830-835.
  4. Bailey RK et al. Lactose intolerance and health disparities among African Americans and Hispanic Americans: an updated consensus statement. J Natl Med Assoc 2013;105:112-127.

Keywords: lactose intolerance , lactose malabsorption , national institutes of health , prevalence

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