In
World War II aircrews discovered (
the hard way) that
gas in the
intestines expands several times over when flying in an
unpressurized aircraft at 20,000 feet and above. This discovery was made because most of World War II aircraft were unpressurized (except for the
B-29) and
World War I aircraft did not achieve the high altitudes that later planes could.
The thinner air at altitude caused the higher-pressure intestinal gases to expand, at great discomfort to the victim. At higher altitudes the crews wore oxygen masks and very warm clothing, but normally the lower pressure was not a problem. Passing gas could be very painful, often debilitating, and sometimes fatal.
With thousands of bombers and fighters flying at those altitudes something had to be done. The solution, of course, was in the diet. Certain foods cause most of intestinal gas. Fliers solved the problem by removing from or reducing in their diets whenever possible beans, cabbage, corn, onions, and other foods that normally cause gas in humans.
This has been another little known (and pretty useless) fact about World War II