Lactose Intolerance

Lactose intolerance is the impaired ability to digest lactose (the naturally occurring sugar in milk). The enzyme lactase is needed to digest lactose, and a few children and many adults do not produce sufficient lactase to digest the milk sugar. The condition is rare in infants.

Only one-third of the population worldwide retains the ability to digest lactose into adulthood. Most adults of Asian, African, Middle Eastern, and Native American descent are lactose intolerant. In addition, half of Hispanics and about 20% of Caucasians do not produce sufficient lactase as adults.1

A simple test for lactose intolerance is to drink at least two 8-ounce glasses of milk on an empty stomach and note any gastrointestinal symptoms that develop in the next four hours. The test should then be repeated using several ounces of cheese (which does not contain much lactose). If symptoms result from milk but not cheese, then the person probably has lactose intolerance. If symptoms occur with both milk and cheese, the person may be allergic to dairy products (very rarely can lactose intolerance be so severe that even eating cheese will cause symptoms). In addition to gastrointestinal problems, one study has reported a correlation in women between lactose intolerance and a higher risk of depression and PMS.2 However, this study is only preliminary and does not establish a cause-and-effect relationship.

Checklist for Lactose Intolerance

Rating Nutritional Supplements Herbs
3Stars

Calcium (for preventing deficiency if dairy products are avoided only)

Lactase

  
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

What are the symptoms of lactose intolerance?

In people with lactose intolerance, consuming foods containing lactose results in intestinal cramps, gas, and diarrhea.

Medical treatments

Over the counter lactase (Lactaid®, Dairy Ease®), an enzyme that breaks down lactose, is used to either pre-treat milk or to be taken during the ingestion of dairy products.

A lactose-free diet is the most effective means of controlling the symptoms of lactose malabsorption in a person with lactase deficiency. However, some lactose-intolerant people can drink milk that has been predigested by the addition of lactase. Those individuals who must avoid dairy products should take supplemental calcium.

Dietary changes that may be helpful

Although symptoms of lactose intolerance are triggered by the lactose in some dairy products, few lactose-intolerant people need to avoid all dairy. Dairy products have varying levels of lactose, which affects how much lactase is required for proper digestion. Milk, ice cream, and yogurt contain significant amounts of lactose—although for complex reasons yogurt often does not trigger symptoms in lactose-intolerant people. In addition, lactose-reduced milk is available in some supermarkets and may be used by lactose-intolerant people.

Many people with lactose maldigestion tolerate more lactose in experimental studies than in everyday life, in which their symptoms may result from other carbohydrates as well. Sucrose and the indigestible carbohydrates lactulose and fructooligosaccharides (FOS) have all been shown to produce symptoms in lactose-intolerant and milk-intolerant people.3

Nutritional supplements that may be helpful

Supplemental sources of the enzyme lactase may be used to prevent symptoms of lactose intolerance when consuming lactose-containing dairy products. Lactase drops may be added to regular milk 24 hours before drinking to reduce lactose levels. Lactase drops, capsules, and tablets may also be taken orally, as needed, immediately before a meal that includes lactose-containing dairy products. The degree of lactose intolerance varies by individual, so a greater or lesser amount of oral lactase may be needed to eliminate symptoms of lactose intolerance.

Researchers have yet to clearly determine whether lactose-intolerant people absorb less calcium. As lactose-containing foods are among the best dietary sources of calcium, alternative sources of calcium (from food or supplements) are important for lactose-intolerant people. A typical amount of supplemental calcium is 1,000 mg per day.

Lactobacillus acidophilus supplements do not appear to be effective in reducing the signs and symptoms of lactose intolerance. In a preliminary trial, people with lactose intolerance were given Lactobacillus acidophilus supplements twice daily for seven days, but failed to show any improvement in symptoms or laboratory measurements of lactose digestion.4

Are there any side effects or interactions?
Refer to the individual supplement for information about any side effects or interactions.

References

1. Gudmand-Hoyer E. The clinical significance of disaccharide maldigestion. Am J Clin Nutr 1994;59(3):735–41S.

2. Ledochowski M, Sperner-Unterweger S, Fuchs D. Lactose malabsorption is associated with early signs of mental depression in females: a preliminary report. Dig Dis Sci 1998;43:2513–7.

3. Teuri U, Vapaatalo H, Korpela R. Fructooligosaccharides and lactulose cause more symptoms in lactose maldigesters and subjects with pseudohypolactasia than in control lactose digesters. Am J Clin Nutr 1999;69:973–9.

4. Saltzman JR, Russell RM, Golner B, et al. A randomized trial of Lactobacillus acidophilus BG2FO4 to treat lactose intolerance. Am J Clin Nutr 1999;69:140–6.