Do probiotics reduce adult lactose intolerance? A systematic review. (APPLIED EVIDENCE: New research findings that are changing clinical practice

Practice recommendations

* Become familiar with the strains, concentrations, and preparations of probiotics most likely to be effective.

* Because a given individual may respond well to probiotics, suggest a trial of a probiotic supplement-perhaps conducting an n-of-1 trial for an objective assessment.

* If a trial of probiotic does not achieve desired results, advise the patient of the many other options to treat lactose intolerance.

Abstract

Purpose To assess the efficacy of oral probiotics in adults with lactose intolerance through a systematic review of its effects on symptoms and breath hydrogen tests, and whether adding probiotics to nonfermented dairy products decreases lactose intolerance at that meal.

Methods We searched randomized controlled trials published between 1966 and December 2002. Databases in the search strategy included Medline and AMED. We reviewed references of clinical trials and contacted authors of major articles and manufacturers of probiotic commercial products. Quality assessment was based on the McMaster guides and was performed by 5 independent reviewers. Data extraction was performed by 2 reviewers.

Results A master list of 90 articles was compiled. Ten articles met inclusion and exclusion criteria and were consistent with our clinical question. Of the 9 studies that measured breath hydrogen, 3 were positive, 3 were negative, and 3 had both positive and negative results. Of the 7 studies that measured symptoms, 1 yielded positive results, 5 were negative, and 1 had both positive and negative outcomes.

Conclusions Probiotic supplementation in general did not alleviate the symptoms and signs of lactose intolerance in adults in this review. Some evidence suggests that specific strains, concentrations, and preparations are effective. Further clinical trials of specific strains and concentrations are necessary to delineate this potential therapeutic relationship.

Judging from our systematic review of the literature, probiotic supplementation is not effective universally for lactose intolerance in adults. However, some evidence suggests that specific strains, concentrations, and preparations of probiotics can be effective.

Discuss probiotic supplementation with lactose-intolerant patients. "Try it" is a reasonable suggestion, given additional evidence that there are individuals whose symptoms of lactose intolerance will, for unknown reasons, respond to probiotics.

For those who find no benefit in probiotics, several other therapeutic options can be recommended.

* Prevailing wisdom about lactose intolerance

Lactose intolerant persons suffer such symptoms as abdominal cramping, bloating, and diarrhea after ingesting lactose-containing foods, including nonfermented dairy products. (1) This intolerance to dairy products may result in a person receiving less than the recommended intake of calcium and protein, especially in developing countries.

Primary lactase deficiency is the most common form of lactose intolerance? In the US, 15% of Caucasians, over 50% of Mexican Americans, and over 80% of African Americans have lactose intolerance. (2)

Treatment options for lactase deficiency

Lactose-intolerant persons digest yogurt, which is fermented, more easily than milk. (2) Nonfermented lactose-containing foods can be consumed in small quantities or with proteins and fats to delay gastric emptying. Nonfermented dairy products are generally tolerated if they are prehydrolyzed to reduce levels of lactose (such as reduced-lactose or lactose-free milk). Finally, synthetic enzyme...