June 13, 2006 (AIDSmeds)—Chronic diarrhea
remains a common problem for people living with HIV, and many doctors
advise restricting the intake of dairy products to prevent or reverse
symptoms. But a recent Canadian study has concluded that moderate dairy
ingestion does not worsen diarrhea in HIV-positive people with chronic
diarrhea, regardless of their lactose-tolerance status.
According
to the American Dietetic Association, approximately 30 to 50 million
Americans are lactose intolerant – an inability to digest lactose, a
sugar found in milk and dairy products. People with lactose intolerance
do not have enough of the enzyme lactase in their small intestine,
which is needed to break down lactose into forms of sugar (glucose and
galactose) that can be absorbed easily. If lactose is not converted
into these simple sugars, it can cause flatulence (gas), bloating,
stomach cramps, and diarrhea.
While there have been some
studies suggesting the people with HIV are more likely to suffer from
lactose intolerance, there haven't been any studies suggesting that
dairy avoidance is beneficial. In fact, there is some concern about a
diet that severely limits dairy products, as they may be needed to help
prevent weight loss and fragile bones (osteoporosis) – two potential problems for those with HIV.
The
new study, conducted by Dr. Jill Tinmouth of the University of Toronto
and her colleagues, evaluated 49 HIV-positive people with chronic
diarrhea, defined as having at least three loose/watery bowl movements
per day for the previous four weeks. Approximately 80% of the
volunteers were on a stable anti-HIV drug regimen and none of the
patients 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 ingested
240 mL of low-fat milk containing 12.5 grams of lactose. For eight
hours after taking the lactose-free and lactose-sweetened milk, the
researchers weighed the total amount of stool excreted by each
volunteer. The higher the weight, the researchers suggested, the
greater 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 ingesting
lactose-sweetened milk was 126.3 grams. The average total stool weight
after ingesting lactose-free milk was 167.6 grams. While there appeared
to 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 surprising
finding was that the lactose-tolerant volunteers had significantly
great stool excretion after ingesting lactose-free milk compared to the
lactose-intolerant volunteers. Stool excretion decreased by 11.3 grams
in the lactose-intolerant volunteers after taking lactose-free milk,
compared to a stool excretion increase of 54.8 grams in the
lactose-tolerant volunteers after taking lactose-free milk. However,
the researchers questioned the real-world significance of the increased
stool in the lactose-tolerant volunteers. "This difference represents
approximately three tablespoons of stool and is unlikely to be clinical
significant," Dr. Tinmouth and her colleagues wrote.
While
Dr. Tinmouth's group pointed out that there are limitations to their
study – for example, there is no "gold standard" method to evaluate
diarrhea symptoms in clinical trials – the researchers concluded that
ingesting moderate quantities of milk containing lactose did not
significantly increase stool excretion or worsen symptoms in
HIV-positive people with chronic diarrhea. These results, they write,
echo those of studies involving HIV-negative volunteers, which also
found that moderate lactose ingestion does not worsen symptoms.
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