The following excerpt was posted on the Zone list today, and I
thought some readers of this list would find it interesting.
Todd Moody
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http://www.eurekalert.org/ and pick "This Week's Releases" (middle column,
second one down.
RESEARCH -- Biological Sciences
Smoked Meats Are Safe, Task Force
Concludes
(posted 1/5/98)
CONTACT: Mike Pariza, (608) 263-7777,
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Nitrites, chemicals used to process hot dogs, smoked
hams, and sausages, have been under fire in recent years
from epidemiologists who had found a link between
cured meats and certain childhood cancers. However,
an interdisciplinary task force of scientists concluded in a
recently issued report that there is virtually no scientific
rationale for this conclusion.
"A critical review of the available information on smoked
food sold in the United States indicates that these foods
are safe," said Michael Pariza, director of the Food
Research Institute at the University of
Wisconsin-Madison and chair of the Council for
Agricultural Science and Technology task force that
issued the report.
The task force, including a world-renowned
epidemiologist and several scientists from the
UW-Madison, cited limitations in the epidemiological
studies and chance for confounding the results.
For instance, in a study that showed hot dogs were
linked to childhood leukemia, bacon and lunch meat did
not show the same relationship even though they have
similar levels of residual nitrites. This led the scientists to
conclude that there may be other factors causing the
relationship, such as the levels of fat, folate, and fruits
and vegetables in the children's diets.
Methodology also limited the epidemiological studies.
The studies had asked participants to recall their dietary
habits. According to Pariza, parents of children who
have cancer may remember or report consumption
differently due to the experience of cancer in their
children. A much stronger study would have parents
record their children's diet for a period of time and
report the incidence of cancer in those children at a later
time.
"Most of the epidemiologists have backed away from
the findings of these studies," Pariza said. "They [the
findings] could even be a statistical fluke due to the rarity
of the cancer."
Curing meat by smoking or salting has been a
preservation method for centuries. At the end of the last
century, scientists discovered that nitrite was a crucial
preservative in the process. Nitrite not only prevents
spoilage, but also reacts with the meat pigment
myoglobin, giving cured meat such as ham its distinctive
pink color. More importantly, nitrite inhibits
microorganisms, such as those that cause botulism, if
they are present.
However, in the 1970s, consumer groups began to
question the safety of nitrite-cured meats. Scientists had
discovered that a chemical reaction between nitrite and
certain components of proteins, called amines, formed
chemicals that could cause cancer in lab animals.
"Nitrites can react with amines to form nitrosamines,
which are known cancer causers," said Robert Cassens,
emeritus professor of animal science at the
UW-Madison who has extensively studied nitrites in
cured meats.
Even so, there have been no nitrosamines found in cured
meats through analytical chemistry techniques, said
Cassens. Hypothetically, a small risk of cancer might
come from nitrites remaining in meat that is eaten by
people who may already have amines in their stomachs,
Cassens said. Certain medicines contain amines, for
example.
Unfortunately there are no reasonable substitutes for
nitrite. "The cancer risk is minimized by minimizing intact
nitrites left in the meat," Cassens said.
The allowable amount of nitrite in cured meat is 1/4
ounce per 100 pounds of meat, a very low level. Also,
since the 1970s, there has been an 80 percent reduction
of residual nitrite in cured meats, so only 10 to 20
percent of the nitrite remains. At the same time,
processors began adding vitamins C and E to meats to
speed up the curing process. These vitamins have been
found to inhibit the formation of nitrosamines in the
stomach in human studies, Cassens said.
Due to these changes, the American Cancer Society in
1996 said that "nitrites in food are not a significant cause
of cancer in Americans." In fact, nitrites and nitrates,
which can be converted to nitrites in the digestive
system, are commonly present in many vegetables, said
Pariza.
For example, according to Pariza, someone eating a
bacon, lettuce and tomato sandwich for lunch will show
an increase in blood nitrite levels. Some of that is due to
the bacon, however a larger amount is due to the lettuce
and the tomato. Nevertheless, research has shown that
the benefits of eating vegetables far outweigh the
concerns about nitrites in the diet. It is also important to
remember that nitrites, alone, do not cause cancer.
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