July 21, 2000 -- Let's face it: Americans are in love with anything that says "fat free" on the label. When walking down the snack aisle of the grocery store, we have our choice of dozens of varieties of chips, pretzels, and crackers that will presumably satisfy our hunger without expanding our waistlines. But could these products actually be harming us nutritionally?
Four years ago, a new fat substitute, or "fake fat," was introduced that could be added to traditionally high-fat, high-calorie foods like potato chips and crackers in place of actual fat. The difference is that the fake fat, known as olestra, is not absorbed by the body like most other foods. Instead, olestra goes along for the ride with the food you eat, but passes out of your body before it can be absorbed and turned into fat.
Sounds ideal. Yet studies done in animals have raised concerns that olestra can interfere with the body's absorption of important vitamins and natural substances called carotenoids, found in fruits and vegetables, that may fight cancer.
A new study in the July issue of the Journal of Nutrition finds that people who reported eating olestra snacks an average of three times a month had no differences in blood levels of vitamins A, D, and E compared with people who don't eat olestra.
The FDA requires olestra snacks to contain supplemental amounts of these vitamins as well as vitamin K, so that if the fake fat interferes with absorption of vitamins from other foods, the vitamins added to the snack take their place.
The survey also found no apparent differences in levels of carotenoids if olestra intake is low. The researchers point out that most of the people in the study didn't eat a large amount of foods containing olestra. However, the researchers relied on the participants to tell them how much they ate, so those results could be off the mark.
Those consuming more than two grams of olestra per day had 15% lower levels of carotenoids in their blood than before the study began. Levels of vitamin K actually increased.
However, according to the Center for Science in the Public Interest (CSPI), a nonprofit consumer nutrition watchdog group based in Washington, a serving size of just one ounce of chips contains eight to ten grams of olestra. To put that in perspective, an individual-sized bag of chips is about one and a half ounces.
"At the levels of consumption that people are eating olestra, there is not evidence that it has an effect on [levels of carotenoids in the blood]," Mark D. Thornquist, PhD, tells WebMD. He adds that people don't eat much carotenoid-containing food in the first place and people didn't eat much olestra in the study, so assessing olestra's effects on carotenoids is difficult. Thornquist, of the Fred Hutchinson Cancer Research Center in Seattle, is lead author of the new study, an ongoing survey of olestra consumption sponsored by Procter & Gamble, maker of olestra.
The real significance of the findings is uncertain because there is no consensus among experts as to what role, if any, carotenoids play in overall health. Bruce M. Chassy, PhD, a member of the committee that reviewed olestra data prior to its approval by the FDA, says that despite suggestions that carotenoids may help prevent cancers such as that of the prostate, several large studies in humans have not shown them to have any cancer-fighting benefits.
Chassy, who is executive associate director of the biotechnology center at the University of Illinois at Urbana-Champaign, says the findings should be reassuring to consumers who like snacks containing olestra.
The CSPI has labeled olestra the "most complained about food additive ever." In a survey the group conducted in Indiana soon after olestra chips hit supermarket shelves, 7% of people reported having diarrhea, cramps, loose stools, or other symptoms after indulging in the savory snacks.
Thornquist says there may be several explanations for the reports of stomach problems associated with olestra.
"It's possible that there is a small fraction of people who, for one reason or another, are sensitive to an ingredient in the product and do therefore have serious adverse reactions," he tells WebMD. "On the other hand, it's also possible that people eat the product and then ... in the next 24 hours have a serious problem that is unrelated, but because they remember eating an olestra-containing food, the problem is attributed to olestra."
CSPI's Michael Jacobson, PhD, says the public has weighed in on the olestra controversy loud and clear. "The products are bombs -- because of price, taste, and [digestive side effects]," he tells WebMD.
Although there are lingering concerns that olestra may be harmful to those who do like the chips and eat them in large amounts, Chassy says that for most people, eating olestra as part of a healthy diet should not cause problems.
"The people who are likely to binge on olestra chips and really eat a lot of them -- 99% have much bigger dietary problems," he says. "They, as a rule, are not eating a balanced diet, not eating fruits and vegetables."