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Prevalence of lactose intolerance among Canadian adults.

Dairy products have been associated with several health benefits including bone health and a reduced risk of hypertension, colon cancer and type 2 diabetes. Many individuals--believing they are lactose intolerant--limit or avoid milk products, potentially compromising not only their calcium and vitamin D intakes, but also their health.


Lactose intolerance is characterized by symptoms such as cramps, bloating, abdominal pain and diarrhea when lactose is consumed in large amounts by individuals with low levels of the intestinal enzyme that digests lactose. Unlike milk-protein allergy, which requires that milk products be avoided, double-blind studies demonstrate that lactose-intolerant individuals can consume moderate amounts of lactose without perceptible symptoms. (1) Because, in Canada, the prevalence of lactose intolerance --whether physician-diagnosed or self-reported--is unknown, we undertook a study to assess the prevalence and correlates of self-reported lactose intolerance in the Canadian adult population. (2)

In our study of 2,251 Canadians age 19 yrs and over, we found the following:

* 16% (or about 1 in 6) reported that they were lactose intolerant with a higher prevalence among women, younger adults, nonwhites, and those who completed the survey in English rather than French, but did not differ by level of education.

* Individuals with lactose intolerance had less favourable beliefs about the healthiness of milk products, and substantially lower intakes.

* Individuals with intolerance consumed less cheese, even though most hard cheeses contain negligible amounts of lactose.

* Individuals with lactose intolerance had significantly lower mean calcium intakes from the combination of milk products, alternatives, and supplements compared to individuals who did not report lactose intolerance (739 mg/d vs. 893 mg/d respectively, p<0.001). (2)

Health professionals should advise individuals with lactose intolerance --whether physician-diagnosed or self-reported--about how to avoid associated nutrient shortfalls by consuming milk products in a way that does not provoke symptoms. (1,2)

Dietary strategies for managing lactose intolerance (1)

* Up to 12 g lactose (e.g., 1 cup of milk) is generally well tolerated.

* Chronic/repeated intake of lactose-containing foods promotes colonic adaptation.

* Consume lactose-containing foods with meals.

* Hard cheeses contain very little lactose and are generally well tolerated.

* Yogurt is usually well tolerated due to bacterial digestion of lactose.

* Use commercially available lactase drops or tablets (that can be added to dairy foods or consumed prior to dairy food intake, respectively).

* Lactose-free milk is a widely available option.


* Calcium consumed as supplements or in fortified soy beverages fails to compensate for lower intakes of milk products.

* In contrast to milk-protein allergy, avoidance of milk products is not recommended for those with perceived or diagnosed lactose intolerance.

* Strategies to manage lactose intolerance without avoiding milk products are recommended.

Susan I. Barr, PhD, RD, FDC Professor

Food Nutrition and Health, Faculty of Land and Food Systems

University of British Columbia
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Title Annotation:nutrition horizons
Author:Barr, Susan I.
Publication:Canadian Journal of Dietetic Practice and Research
Article Type:Report
Geographic Code:1CANA
Date:Jan 1, 2013
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