Washington Post, DC
04-25-07
Chat Plus: Edamame
Chicago: Help! The Chicago Tribune printed a reader's letter warning that eating
edamame inhibits the body's ability to digest protein and might be unhealthy in
other ways. Some quick Internet research hasn't turned up much credible
reporting (man, there are some nuts out there!), but I'm concerned because I love
edamame. I eat the frozen kind all the time and love to serve it as a party snack.
Do you have any info about detrimental health effects of edamame, or can you
point me in the right direction (i.e., to someone who is not a conspiracy theorist)?
Bonnie S. Benwick: Not to worry. According to Lester Wilson, a food science
and human nutrition specialist at Iowa State University in Ames, raw
soybeans contain an enzyme called trypsin as well as trypsin inhibitors, which
are natural compounds that can affect the body's ability to break down proteins.
(For non-science types, Wilson likened this to a key that is jammed in a door
lock, preventing the door from being opened. We generate such enzymes in our
bodies, too.)
Most likely, the edamame you're snacking on is not raw. It has been blanched,
steamed, roasted or otherwise heat-treated, the professor says, which will
inactivate or denature the inhibitor that might otherwise bind with the enzyme and
keep you from getting all of the protein benefit of eating soy.
Depending on the temperature and heating time involved, a tiny amount of
trypsin inhibitor might remain, but not enough to cause harm (it might even be
good for you because it is thought to be an anti-cancer compound), unless
perhaps your immune system is severely compromised.
That said, Wilson recalls that long ago, protein quality testing done on rats did
result in data that showed adverse effects of soy on the rats' development. But in
that instance, Wilson says, the rat model and human model were apples and
oranges, so to speak. We have more enzymes to digest proteins in our bodies
than rats do.