Feb. 14, 2000 (New York) -- People who eat olestra-containing potato chips and snacks may mistakenly test positive for malabsorption -- a condition marked by the impaired absorption of fat in the body (steatorrhea). Such results may lead to unnecessary medical tests.
Reporting in the Feb. 15 issue of the Annals of Internal Medicine, a research team led by Ranga Balasekaran, MD, found that people who regularly consume olestra-containing potato chips may test false-positive for steatorrhea because they too are likely to have high amounts of fat in their feces due to the unique chemical composition of olestra. Balasekaran is a senior gastroenterology fellow at Baylor University Medical Center in Dallas.
The pancreas helps to digest food in the stomach and aids in the absorption of fat from food. When the pancreas is not working properly, malabsorption of fat may occur. "If we don't know if a patient is eating olestra, and we see a huge amount of fat in the stool, then we will think the pancreas is not working properly and we will order expensive and sometimes risky tests," Balasekaran tells WebMD.
Olestra was approved in January 1996 by the FDA for use in place of fats and oils in prepackaged savory snacks. Olestra aims to reduce a food's fat and calories while maintaining its texture. Due to its chemical makeup, olestra is not digested or absorbed by the body. Thus, it may cause abdominal cramping and loose fatty stools.
In the study, 10 healthy volunteers consumed five ounces of traditional potato chips each day on days one through six of the experiment. On days seven through 12, participants consumed five ounces of potato chips containing 40 grams of olestra.
"When participants consumed 40 grams of olestra per day, the excretion of fecal [stool] fat increased to levels observed in patients with steatorrhea caused by the malabsorption syndrome," Balasekaran and colleagues write. "Intake of olestra in any quantity will proportionally elevate measured fecal [stool] fat output and may erroneously suggest malabsorption of dietary fat," they conclude.
Seven grams per day is considered the upper limit of normal for stool fat output, but when participants consumed 40 grams of olestra per day, their stool fat output measured between 14 to 23 grams per day.
"If you are having a fecal [stool] fat test, don't eat olestra products for a week," he advises. Stool fat tests are ordered for diarrhea or weight loss to assure that the pancreas is functioning properly.
"It's important that when you see your doctor for gastrointestinal [stomach-related] symptoms that you tell him or her if you ate or eat olestra-containing products because the doctor may not ask about it," advises Michael F. Jacobsen, PhD, executive director of the Center for Science in the Public Interest in Washington, D.C., in an interview with WebMD.
Olestra may be causing the stomach-related distress, he says, but other causes may also be responsible and doctors should not be too quick to blame olestra.
Olestra products are fortified with fat-soluble vitamins -- vitamins A, D, E and K -- because these vitamins may be excreted with the fat. However, olestra may also reduce the absorption of carotenoids such as beta-carotene and other nutrients that may play a role in preventing certain types of cancer and cataract.
These are some of the reasons why there was controversy surrounding Olestra's release.
In a related study of just over 1,000 people from Indianapolis, researchers found that 41.5% of participants reported consuming an olestra-containing product at least once during the study period.
People who said that they thought it was important to eat a low-fat diet were five times more likely to eat olestra-containing products than were people who did not think eating a low-fat diet was important, according to the study in February Journal of the American Dietetic Association.
In the study, sporadic consumers reported eating the products about 1.3 times per month on average, while consistent consumers ate olestra-containing products an average of 3.1 times per month.
"We didn't know who would choose to eat these products because they got some bad media coverage due to their potential effects on the gastrointestinal system and, on the other hand, they are a low-fat food," lead researcher Dianne Neumark-Sztainer, PhD, MPH, RD, tells WebMD. Neumark-Sztainer is an associate professor of epidemiology at the University of Minnesota School of Public Health in Minneapolis. "We found that people who are health conscious have a higher tendency to consume the chips."
Neumark-Sztainer and colleagues undertook the study to see what types of people were using olestra. After the product was introduced, they questioned volunteers about their diets three times during nine-month intervals.
- People who eat olestra chips and snacks could falsely test positive for a malabsorption disorder, leading to expensive and unnecessary tests.
- Olestra, a fat-based chemical, is designed not to be absorbed by the body, so fecal tests of consumers show an unusually high amount of fat.
- If you eat olestra and are going in for gastrointestinal symptoms, be sure to inform your doctor.