If you've been grocery shopping lately, you know that there are
many new food products positioned to enhance health or reduce the risk
of disease. Many consumers want to take charge of their health and well
being and are seeking foods that optimize their health. One health
concern that some people are addressing with food is cancer. Experts now
believe that what we include in our diet is just as important as what
Many consumers believe that food plays a significant role in
maintaining or improving overall health and are aware that certain foods
may have health benefits beyond basic nutrition. The Food Marketing
Institute/Prevention's Shopping for Health 2000 survey reported that
more than 70 percent of consumers make grocery store purchases on the
basis of their desire to reduce their risk of specific illnesses. In
addition, more than 9 in 10 consumers believe that fruits, vegetables,
and grains contain naturally occurring substances that can help reduce
the risk of diseases such as cancer.
Cancer is a generic term describing
more than 100 diseases that share the uncontrolled reproduction of
abnormal cells. Scientists are just beginning, however, to understand
the many causes of cancer and the complex process by which cancer cells
grow (see the sidebar How Does Cancer Begin?). Each year in the United
States almost 1.4 million new cases of cancer are diagnosed and cancer
causes more than 500,000 deaths.
Over the past two decades, it has become increasingly clear that what
we eat plays a significant role in our risk of cancer. Scientists
estimate that approximately 30 to 40 percent of all cancers are linked
to diet and related lifestyle factors. In short, simple changes in
eating patterns could have a dramatic impact on reducing cancer rates.
The Food-Cancer Connection
The idea that foods
may play a role in reducing one's risk of cancer first emerged from
findings that linked higher levels of intake of fruits and vegetables
with a lower risk of cancer. Since then, many studies have explored the
connection between food and cancer risk. Alan Kristal, associate head of
the Cancer Prevention Research Program at the Fred Hutchinson Cancer
Research Center, explains why results are still speculative: "With
cardiovascular disease, blood cholesterol level is a key biomarker for
measuring the effects of diet. We're just now learning about some of the
various biomarkers for cancer because it is such a complex process."
To date, we believe that the functional components of food that may
reduce one's risk of cancer include traditional nutrients, such as folic
acid, vitamins A and C, fiber, and selenium, as well as recently
discovered compounds, such as phytochemicals and many other naturally
occurring elements in both plant and animal foods. Some functional
components, lycopene in tomatoes and tomato products, act as potent
antioxidants, protecting cells against harmful damage from oxidation.
Interestingly, research shows that lycopene is more bioavailable in
processed tomatoes. Others, such as soy, have hormone-like actions,
helping to protect against hormone-dependent cancers like endometrial
and ovarian cancers.
More recently, it has been discovered that compounds in food-such as
sulforaphane in broccoli-can encourage the body's production of
protective enzymes, called phase II enzymes. These enzymes help to
detoxify cancer-causing substances and prevent cell damage that can lead
to cancer. Other such foods include cruciferous vegetables (e.g.,
cabbage, cauliflower, brussels sprouts, and bok choy), garlic, onions,
berries, and grapes.
Certain food components may also be able to help delay, regress, or
inhibit the advancement of cells to the clinical stage of cancer.
However, Dr. John Milner, chief of the Nutritional Science Research
Group at the National Cancer Institute, cautions that "one size does not
fit all" when it comes to benefits from functional foods.
"The evidence is compelling that functional foods can modify cancer
risk, especially with increased intakes of fruits and vegetables," says
Milner. "But it also appears that not everyone gets the same benefits.
An individual's genetic makeup probably influences the extent of the
response to functional food components." According to Milner, this may
explain why some people seem to experience positive effects from
functional components of food while others do not. "Until more targeted
intervention-based research is conducted, it's difficult to predict who
might benefit from functional foods."
The table below, Functional Foods that May Reduce Risk of Cancer,
lists some functional compounds in foods and their potential roles in
cancer risk reduction.
Whole Foods vs. Prepared Foods
namely fruits and vegetables, represent the simplest example of
functional foods. Prepared foods, such as breads, cereals, dairy
products, and juices, that have been enriched or fortified with
"traditional" nutrients, are also functional foods. Some newer
functional foods include foods that have been enhanced with
phytochemicals, botanicals, or other functional substances.
Although it may be possible to isolate specific components of food
that may reduce the risk of diseases like cancer, it is unclear whether
isolated active compounds added to food have the same health benefits as
whole foods because compounds in foods may act synergistically to
impart health benefits.
"It's likely that the protective effects of functional foods come
from vitamins, minerals, enzyme-boosting phytochemicals, and perhaps
other not-yet-identified substances in food, all working together," said
Clare Hasler, executive director of the Functional Foods for Health
Program at the University of Illinois. "As we learn more about actions
of functional components and the effects on individuals," she adds, "we
may be able to tailor functional food recommendations based on an
individual's genetic profile."
There's no doubt that functional foods' role in reducing the risk of
cancer is promising. For now, getting the full range of "functions" from
food means eating a variety of foods and including plenty of fruits and
vegetables in your diet. Until we know more, this strategy along with
an overall healthful lifestyle offers the best bet for improving the
odds against developing cancer.
For More Information on Functional Foods
How Does Cancer Begin?
This box provides a
simplified explanation of the stages that occur before cancer becomes
The first stage, called initiation, occurs when a normal cell is
exposed to a carcinogen, such as chemicals, viruses, radiation, or
specific dietary factors. Essentially, anything that causes damage to
the cell membrane or the DNA material within the cell can be classified
as a carcinogen. DNA repair mechanisms can usually restore the cell to
its normal state. If the cell is unable to repair itself, however, it
mutates. A mutated, or initiated cell, passes on its mutation when it
replicates, thus advancing from the initiation to the promotion stage.
At the promotion stage, the cell may experience spontaneous remission
back to the initiation stage, or it may be exposed to growth inhibitors
or antipromoters, such as antioxidants and phytochemicals, that will
allow regression back to the initiation stage. However, the mutated cell
may eventually lose its integrity and develop into a premalignant
lesion such as dysplasia, carcinoma in situ, or polyps. As the cell
continues to lose control over its function and structural integrity,
progression to the clinical stage of cancer occurs with disruption of
normal body functions. The entire process, from exposure to a carcinogen
to development of cancer, typically takes years.
Functional Foods that May Reduce
Risk of Cancer
|| Functional Components*
|| Possible Role(s) in Cancer Risk Reduction
|Broccoli and broccoli sprouts
||Stimulates the body to produce its own protectivephase II enzyme,
neutralizes free radicals
|Tomatoes and tomato products
||Potent antioxidant that may reduce risk of prostate cancer
|Garlic and onions
||Boosts levels of naturally occurring enzymes that may help maintain
healthy immune system
||Isoflavones (genistein and daidzein)
||May act as an antiestrogen, plugging up receptors for estrogen which
may reduce the risk of estrogen-dependent cancers; may inhibit the
formation of blood vessels that assist tumor growth
|Grapes, strawberries, and raspberries
||May block the body's production of enzymes needed for cancer cells
|Oranges and lemons
||Boosts levels of naturally occurring enzymes that may break down
||May help block damage to DNA by neutralizing free radicals and
reducing cancer risk
|Beef and dairy
||Conjugated linoleic acid (CLA)
||May decrease risk of certain cancersproducts
||May inhibit tumor cell growth and induce cell death
||Acting as a phytoestrogen, may offer reduced risk of certain kinds
||May suppress the oxidative reactions in the colon that produce
damaging free radicals
* These represent just one example of
functional components in the corresponding food. Most functional foods
contain many active components with potential health benefits.