Olestra does not cause anal leakage.
So said a report I heard on NPR a couple of years ago. According to the report as I remember it, the product testing required people to eat large quantities of Olestra potato chips every meal for several days. People did have side effects, including the infamous anal leakage. These side effects were not caused by Olestra, per se, but by the massive consumption of greasy potato chips. Eating the same quantity of regular potato chips also results in anal leakage.
Nonetheless, the regulatory agency (probably the FDA) wanted that warning on the chips. The company that developed and owned Olestra (J&J ?) miscalculated and went to market with the warning instead of fighting it. They thought it would be like many other warning labels which were read and discarded. They did not predict what a boon the phrase “anal leakage” would be to professional and amateur commedians, some on this board.
When released, some consumer group got a record number of complaints about the side effects, far more than the research indicated should happen. Apparently, the warnings got such air play that people were attributing every semi-soft poo within 6 months of contact of a chip to Olestra.
I remember them saying that the regulatory agency now agreeded that the results of the test did not warrant the label. However, last time I looked there still was a warning.
Again, I heard this probably a couple years ago, so take the details I’ve listed with a grain of anal leakage.