April
18, 2003
One
of the current “hot topics” in
health research is how inflammation affects our risk
of heart disease, stroke, diabetes and even cancer.
Scientists are increasingly focused on a certain
kind of inflammation — specifically, the form
that takes place deep in our cells and tissues — and
the important role it may play in the development
of disease.
Normally, inflammation is a good sign.
When your thumb swells up after you accidentally bang it
with a hammer, it tells you
that your immune system is sending white blood cells and
other, hormone-like substances to help start
the healing process.
But not every kind of inflammation is that easy to see,
and it’s the invisible kind that takes
place throughout our body, over and over again,
that is attracting so much
attention.
COX-2 is an enzyme in our bodies that boosts
the production of inflammatory chemicals. Normally, these
proteins and hormone-like substances are churned out by our
immune systems
with no ill effects.
Under certain conditions, however, they
may actually help cancer cells multiply and spread. That’s
why one type of anti-inflammatory drugs, collectively called
COX-2 inhibitors, are under study for a potential role in
preventing or treating cancers of the colon, uterus, breast,
prostate
and other tissues.
DOES NUTRITION PLAY A ROLE?
And now, scientists are investigating whether
the way we eat and digest our food could also influence the
kind of chronic inflammation that might be linked to cancer
risk and other health problems.
Around the world, different researchers
are focusing on different aspects of the issue. Some are
looking at how two families of polyunsaturated fats may work
together
to play a protective role.
Omega-3 fats are found mainly in fatty
fish such as salmon, mackerel, and albacore (white) tuna, but
are also found in flaxseeds and flaxseed oil, walnuts and canola
oil. Omega-6 fats are found in many common vegetable oils (corn,
safflower, sunflower). All are considered heart-healthy because
they don’t raise blood cholesterol. But when omega-6
fats predominate over omega-3 fats, something else happens:
our bodies seem to increase COX-2 levels and produce more
of the hormone-like substances that promote inflammation.
When
omega-3 and omega-6 fats are more balanced in the diet, fewer
of these inflammatory substances are produced.
This is why some scientists believe that
if we boost omega-3 fats with regular consumption of naturally
fatty fish or sources like flax, and reduce our excess use
of vegetable oils, spreads and high-fat snacks made with
them, we might make the COX-2 in our bodies less active, and
decrease
the amount of inflammatory hormones that might be associated
with cancer risk.
INFLAMMATION AND OBESITY
Other scientists are seeking to determine
if inflammation may be one reason that obesity has been linked
to higher cancer risk. Research now suggests that the body’s
fat cells produce cytokines (proteins that promote low-grade
inflammation) and that the distribution of body fat might
also play a role.
A study in the Journal of the American
Medical Association shows that one measure of inflammation
increased by more than 50 percent in obese women whose fat
was mainly in their hips and thighs (“pear-shaped”),
and by more than 400 percent in obese women with significant
waistline fat (“apple-shaped”).
Interestingly, some studies now show that
regular exercise may have precisely the opposite effect on
the immune system, and may reduce levels of inflammatory
proteins. This might help to explain why research has linked
regular
physical activity with lower cancer risk.
RESEARCH ON PLANT-BASED DIETS
Still other scientists, including many sponsored by
the American Institute for Cancer Research, are investigating how an overall
plant-based diet might help keep inflammation in check. Antioxidant nutrients
and phytochemicals in fruits and vegetables protect cells’ DNA from damage
that can lead to cancer; and some evidence now suggests they may also lower
production of inflammation-promoting hormones. In fact, a wide variety of natural
phytochemicals
found in fruits and vegetables are under investigation for possible COX-2 lowering
effects.
All of this evidence linking diet to the kind of chronic
inflammation associated with cancer risk is still preliminary, however, and it
would be premature to change our diets if this was the only reason to do so.
Of course, it isn’t the only reason — a plant-based diet with plenty
of fruits and vegetables, maintenance of a healthy weight and regular exercise
is already a strategy that is estimated to lower cancer risk by 30 to 40 percent.
We know that it works — the incoming research about inflammation may
soon help us get a better idea of some of the how and why.
Nutrition
Notes is provided
by the American Institute for
Cancer Research in Washington, D.C.
