Lactase

What does it do?

Lactase is the enzyme in the small intestine that digests lactose (the naturally occurring sugar in milk).

A few children and many people after childhood do not produce sufficient lactase, resulting in impaired ability to digest milk. These people are lactose intolerant and often suffer from symptoms including cramps, gas, and diarrhea. Lactose intolerance is best diagnosed by a doctor, However, a reasonably reliable home test for lactose intolerance is to drink two 8-ounce glasses of milk on an empty stomach and note any gastrointestinal symptoms that develop over the next four hours; repeat the test on another day 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.

Where is it found?

Lactase is produced by the body. 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 doesn’t trigger symptoms in lactose-intolerant people.

Lactase has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating	Health Concerns
	Diarrhea (for lactose-intolerant people) Indigestion and heartburn (for lactose-intolerant people) Irritable bowel syndrome (for lactose-intolerant people) Lactose intolerance
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Rating

Health Concerns

Diarrhea (for lactose-intolerant people)

Indigestion and heartburn (for lactose-intolerant people)

Irritable bowel syndrome (for lactose-intolerant people)

Lactose intolerance

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.

Who is likely to be deficient?

Only one-third of all people retain the ability to digest lactose into adulthood. Most individuals of Asian, African, and Native American descent are lactose intolerant. In addition, half of Hispanics and about 20 percent of Caucasians do not produce lactase as adults.¹

How much is usually taken?

Lactose-reduced milk is available and can be used in the same quantities as regular milk. Lactase drops can be added to regular milk 24 hours before drinking to reduce lactose levels. Lactase drops, capsules, and tablets can also be taken directly, 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 lactase may be needed to eliminate symptoms of lactose intolerance.

Are there any side effects or interactions?

Lactase is safe and does not produce side effects.

Some, but not all, studies suggest that lactose-intolerant individuals absorb less calcium.²

At the time of writing, there were no well-known drug interactions with lactase.

References

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

2. Wheadon M, Goulding A, Barbezat GO, et al. Lactose malabsorption and calcium intake as risk factors for osteoporosis in elderly New Zealand women. NZ Med J 1991;104:417–9.

Learn more about Healthnotes, the company.

Learn more about the authors of Healthnotes.

The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over-the-counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2005.