December 7, 2014
Susan I. Barr
Food, Nutrition & Health, University of British Columbia, Vancouver, BC, Canada
Insufficient dairy consumption has been associated with adverse health outcomes, including osteoporosis, hypertension, and increased risks of 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 that occur when large amounts of lactose (the sugar in milk) are consumed by those with low levels of lactase, the enzyme that digests lactose. In Canada, the prevalence of lactose intolerance – whether physician-diagnosed or self-reported – is unknown. Accordingly, we assessed the prevalence and correlates of self-reported lactose intolerance in the Canadian adult population. We also examined associations with milk-product intakes; calcium and vitamin D supplement use; and estimated calcium and vitamin D intake from milk products, alternatives, and supplements.
In our nationally-representative sample of 2,251 Canadians aged >19 y, 16% (about 1 in 6) reported that they were lactose intolerant. The prevalence was significantly higher in those who reported a race/ethnicity other than “White”, which was expected as lactase levels are generally lower in these individuals. However, it was also higher in younger versus older adults, women versus men, and those who completed the survey in English rather than French. There is no physiological explanation for these differences, which suggests that in some cases the condition may have been “perceived” rather than “real”.
Almost all respondents reporting lactose intolerance had reduced their intakes of milk, cheese and yogurt. Although they were somewhat more likely to use fortified soy beverages and supplemental calcium and vitamin D, this didn’t compensate for their low intakes of milk products. They 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). Mean intakes of both groups were below current recommendations (1000 mg for those aged 19-50 y, and 1200 mg for women >50 y and men >70 y).
Unlike milk protein allergy, avoiding milk products is not recommended for those with lactose intolerance. Instead, the best solution is to limit the amount of lactose consumed at one time. Double-blind studies show that people who don’t digest lactose can consume moderate amounts of lactose with meals (~12 grams, or about 1 cup of milk) without perceptible symptoms. Thus, it is important that health professionals advise individuals with lactose intolerance – whether physician-diagnosed or self-perceived – about how to avoid the associated nutrient shortfalls. Practical suggestions include:
- Hard cheeses (e.g., cheddar, Swiss, etc.) contain almost no lactose.
- Yogurt is usually well-tolerated because lactose can be broken down by the bacteria it contains.
- Consume lactose-containing foods with meals, starting with small amounts.
- Consider use of commercially-available lactase drops or tablets (that can be added to milk or consumed before eating dairy products).
- Lactose-free milk is also available.
- Barr SI. 2013. Perceived lactose intolerance in adult Canadians: a national survey. Appl. Physiol. Nutr. Metab. 38(8):830-835. Available at: http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2012-0368#.U2Kf-_ldXJI
- National Institutes of Health. 2010. NIH Consensus Development Conference Statement: Lactose Intolerance and Health. NIH Consens State Sci Statements Feb 24;27(2):1-27. Available at: http://consensus.nih.gov/2010/lactosestatement.htm
If you intend citing any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Transfer Committee.