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Colon Cancer
Risk: Meat and How It’s Cooked
Research is convincing that eating
too much red and processed meat increases risk of colorectal
cancer, according to a major report by the American Institute
for Cancer Research. Now, a large population study suggests that
how you cook your meat – white and red meat – is also
important. The European study linked increased risk of pre-cancerous
growths in the colon to cancer-causing compounds that form when
meat is grilled or fried at high temperatures.
This study questioned more than
25,000 adults about details of their diets, including what and
how much red meat and poultry they ate and how it was cooked.
Based on this, researchers estimated levels of three major heterocyclic
amine (HCA) compounds typically consumed. HCAs form when long
or intense heat reacts with animal muscle, both red and white
meat, as well as fish. These compounds can damage our DNA and
begin the development of cancer. |
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As in past studies, people who
ate more red and processed meat were more likely to develop colorectal
adenomas (benign tumors that can transform into cancerous ones
and are the source of most colorectal cancer). Consumption of
all three of the major HCAs was also higher among those who developed
adenomas. Looking only at the left section of the colon that
seems most vulnerable to meat-associated risks, those with greatest
consumption of the most abundant HCA were 59 percent more likely
to develop adenomas than those who consumed the least.
Laboratory and smaller human
studies have studied HCAs’ impact on cancer risk for years,
but this European study was only the second large population
study examining the issue. Previously, a major U.S. study examined
more than 14,000 men to see how HCA consumption was linked to
adenoma in that left section of the colon most sensitive to meat’s
impact.
The U.S. researchers suggested
that looking at total HCA consumption may provide an unclear
picture because that total figure could include varied proportions
of HCAs that are more or less damaging. Besides, colon cancer
and adenoma risk may relate not only to HCAs, but also to other
damaging compounds formed in cooking. A total cell-damaging score
(created by methods from previous research) was more strongly
linked to left colon adenoma risk than any individual HCA, though
even here the link was not strong. Consumption of processed meat
presented the strongest association. Yet consumption of total
cell-damaging compounds seemed to be a separate influence, even
after accounting for processed meat intake.
Together, these and other studies
tell us that although a primary step to lower risk of colon cancer
is limiting red and processed meat, the issue of how our meat,
poultry and fish is cooked is also important. The HCAs and other
cell-damaging compounds that form when meats are cooked with
high temperature grilling and frying, especially when well-done
or extremely browned, are not carcinogenic on their own. Proteins
in our body must activate them and activation depends upon both
diet and genetics. The effect we see in studies is likely an
average of individuals who are strongly and not strongly affected.
The bottom line for consumers
is to watch what you eat and how it’s cooked. Avoid frying
and if grilling, reduce the temperature and don’t char food.
A mostly plant-based diet plays an important protective role:
less meat automatically means less of meat’s cell-damaging
compounds and more plant foods mean more of the protective compounds
that inactivate the damaging ones. |
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