June 13, 2006 (AIDSmeds)—Chronic diarrhearemains a common problem for people living with HIV, and many doctorsadvise restricting the intake of dairy products to prevent or reversesymptoms. But a recent Canadian study has concluded that moderate dairyingestion does not worsen diarrhea in HIV-positive people with chronicdiarrhea, regardless of their lactose-tolerance status.

Accordingto the American Dietetic Association, approximately 30 to 50 millionAmericans are lactose intolerant – an inability to digest lactose, asugar found in milk and dairy products. People with lactose intolerancedo not have enough of the enzyme lactase in their small intestine,which is needed to break down lactose into forms of sugar (glucose andgalactose) that can be absorbed easily. If lactose is not convertedinto these simple sugars, it can cause flatulence (gas), bloating,stomach cramps, and diarrhea.

While there have been somestudies suggesting the people with HIV are more likely to suffer fromlactose intolerance, there haven’t been any studies suggesting thatdairy avoidance is beneficial. In fact, there is some concern about adiet that severely limits dairy products, as they may be needed to helpprevent weight loss and fragile bones (osteoporosis) – two potential problems for those with HIV.

Thenew study, conducted by Dr. Jill Tinmouth of the University of Torontoand her colleagues, evaluated 49 HIV-positive people with chronicdiarrhea, defined as having at least three loose/watery bowl movementsper day for the previous four weeks. Approximately 80% of thevolunteers were on a stable anti-HIV drug regimen and none of thepatients had evidence of an infection known to cause chronic diarrhea(intestinal parasites, etc.).

On one day of the study,all of the volunteers – ten of whom had documented lactose intolerance– ingested 240 mL of lactose-free milk. On another day, they ingested240 mL of low-fat milk containing 12.5 grams of lactose. For eighthours after taking the lactose-free and lactose-sweetened milk, theresearchers weighed the total amount of stool excreted by eachvolunteer. The higher the weight, the researchers suggested, thegreater the diarrhea.

According to the research team’s report, published in the June 12th issue of Archives of Internal Medicine,the average total stool weight within eight hours after ingestinglactose-sweetened milk was 126.3 grams. The average total stool weightafter ingesting lactose-free milk was 167.6 grams. While there appearedto be slightly more stool excretion after ingesting lactose-free milk –a surprising finding – the difference was not statistically significant(it could have been due to chance).

Another surprisingfinding was that the lactose-tolerant volunteers had significantlygreat stool excretion after ingesting lactose-free milk compared to thelactose-intolerant volunteers. Stool excretion decreased by 11.3 gramsin the lactose-intolerant volunteers after taking lactose-free milk,compared to a stool excretion increase of 54.8 grams in thelactose-tolerant volunteers after taking lactose-free milk. However,the researchers questioned the real-world significance of the increasedstool in the lactose-tolerant volunteers. “This difference representsapproximately three tablespoons of stool and is unlikely to be clinicalsignificant,” Dr. Tinmouth and her colleagues wrote.

WhileDr. Tinmouth’s group pointed out that there are limitations to theirstudy – for example, there is no “gold standard” method to evaluatediarrhea symptoms in clinical trials – the researchers concluded thatingesting moderate quantities of milk containing lactose did notsignificantly increase stool excretion or worsen symptoms inHIV-positive people with chronic diarrhea. These results, they write,echo those of studies involving HIV-negative volunteers, which alsofound that moderate lactose ingestion does not worsen symptoms.