These
charts show how what you eat affects your cancer risk.
By Sara Chodosh May 22,
2019
Diet really does make a
difference.DepositPhotos
However much we might like
to believe that a detox tea
or a super-berry will
prevent us from getting cancer, the truth is a more bitter pill: anyone can get
cancer no matter what kind of lifestyle they follow, but eating healthy foods
and exercising regularly is the best way to lower
your risk.
But that's so much less
satisfying, isn't it? "Eating healthy" is this ambiguous idea that
might seem only tangentially related to cancer, whereas eating an antioxidant
that supposedly blocks free radicals feels like much more direct action. And
yet the truth is that just as many cancer cases are caused by poor diet as by
drinking alcohol, and even more are tied to the excess body weight that
comes with eating that poor diet.
Oldie but goodie @CaulfieldTim
Roughly two out of every five cancer cases in America are
preventable by a modifiable risk factor, from alcohol
consumption to physical inactivity and, of course, cigarette smoking.
That's more than 659,000 cases annually. Of those, a new study in the journal JNCI Cancer
Spectrum estimates that more than 80,000 (at least in 2015) were
attributable to suboptimal diet.
So what does that actually
mean? How does diet influence our cancer risk? We'll break it down for you.
Colorectal cancer is on the
rise, especially in younger generations. Infographic by Sara Chodosh
How do
certain foods affect my cancer risk?
Most of the breakdowns of
diet and cancer focus on seven major food groups: fruits, vegetables, whole
grains, processed
meats, red meat, dairy, and sugar-sweetened beverages (sugar science is
complicated, since fruits also have plenty of sugar,
so researchers focus on sweet drinks since they're unequivocally bad for you).
Most Americans—in fact, most people around the world—don't
eat the right amount of any of these kinds of food. We consume far too much sugar and
red or processed meat without getting nearly enough fruit, veggies, whole
grains, or dairy.
Some of those food groups
have a very
direct influence on our health. The fiber in fruits, veggies, and whole
grains, for instance, feeds a
robust gut microbiome. Processed and red meats contain various molecules that
promote cancer. But other foods, like sugar, are cancer-inducing in a less
direct way: they make us gain weight. People who are considered overweight
can be perfectly healthy, but on average, being obese comes with increased
health risks—including a higher risk of cancer.
Fat but fit is absolutely
possible, but excess weight still has an impact. Infographic by Sara
Chodosh
Here's a more in-depth
breakdown of how these foods influence our cancer risk, all courtesy of
the World Cancer Research Fund's thorough report on diet and cancer.
Whole
grains
Processed grains, like
those in white flour, don't contain the whole grain kernel—but it's the whole
grain that contains all the nutrients. The bran and germ bits include nutrients
like vitamin E, copper, zinc, and selenium, plus lignans and phytoestrogens
that researchers think could have anti-carcinogenic properties.
They're also full of fiber, which feeds healthy gut bacteria, ferments into
short-chain fatty acids that may help prevent cancer, and move your bowel
contents along (which may decrease the chances that a mutagenic compound in
your feces comes in contact with your intestinal cells).
All of this contributes to
a healthy colon that’s low in inflammation. We hear a lot about inflammation
and cancer—the basic idea is that inflammatory reactions are intended to kill
potential invaders like bacteria, because generally your body is inflamed in
response to a bodily threat. A cut on your hand, for instance, is less likely
to get infected because your body produces chemicals that induce mutations in
potential pathogens like bacteria. But those same chemicals damage your own
cells. That’s not a problem on a small scale, but chronic inflammation ends up
promoting cancer.
Diets low in whole grains
tend to promote inflammation and lead to an unhealthy gut overall, which is why
they're primarily associated with colorectal cancer.
Dairy
products
You might be used to
thinking of dairy as bad because Americans have been told for decades
that fat is evil.
Fat is not wholly evil, and though it's calorie-dense there are tons of dairy
options that are lower in fat and quite healthy for you. For one, dairy is high
in calcium, which research suggests could be protective for your colon (though
it's not clear exactly how). And then there are the lactic
acid-producing bacteria that give yogurt and other fermented dairy products
their characteristic tang. Those bacteria contribute to your gut microbiome and
seem to inhibit cancer formation through a variety of pathways.
These factors all seem to
help protect your colon cells from becoming cancerous.
There is one potential
drawback to dairy (apart from saturated fat), which is that high calcium
content might be associated with a slightly increased risk of
prostate cancer. Greater milk consumption has been associated with a small
elevation in levels of a growth factor called IGF-1, which in turn is
associated with a higher risk of prostate cancer. For that reason, dairy isn't
often endorsed as wholly anti-cancer. On the other hand, calcium also appears
to exert some protective effects by regulating vitamin D levels. Breast cancer
risk seems to go down with higher calcium intake for this reason.
A balanced diet is the
healthiest one.Infographic by Sara Chodosh
Processed
and red meats
The carcinogenic effects of
these meats are pretty much all tied to three types of molecules: heterocyclic
amines, polycyclic aromatic hydrocarbons, and N-nitroso compounds. The first
two form in red and processed meats during high-temperature cooking, while your
colon produces the third when it’s exposed to high levels of heme iron (which
is what gives red meat its hue). Processed meats also contain nitrates and
nitrites, both of which may contribute to the formation of N-nitroso compounds.
These molecules contribute to cancer risk in multiple organs, including the
colon, the stomach, and the pancreas, by directly causing mutations in cells
that can add up over time.
Fruits
and vegetables
Apart from all the
aforementioned benefits of fiber, fruits and veggies also have tons of
nutrients and phytochemicals that research suggests are anti-tumorigenic. These
include everything from carotenoids to flavonoids to vitamins A, C, and E. A
lot of the benefit from these compounds goes toward the various elements of
your GI tract, from your mouth to your stomach to your colon. But they also
help prevent others, like breast, lung, and bladder cancer, most likely through
the same pathways.
Sugar-sweetened
beverages
Unlike the rest of these
dietary factors, sugar doesn't have any direct cancer-causing or -preventing
properties. Instead, it contributes by promoting weight gain. Though there are
plenty of ways to get healthier if you're overweight or obese (regular exercise
can help your metabolism shift toward a heart-healthy level even if you don't lose weight!), fat
mass still contributes to cancer.
One method is that ol’
buddy inflammation. Body fat induces chronic inflammation through several
pathways, including by directly producing pro-inflammatory chemicals, and is
associated with higher levels of insulin, which can promote the excess cell
growth that increases a person’s cancer risk.
Excess body fat also
influences hormone levels, since fat cells are a significant storage site for
hormones. This is especially true for postmenopausal women, who are no longer
producing high levels of estrogens from their ovaries and thus get most of
their sex hormone exposure from body fat.
Will
eating healthier prevent me from getting cancer?
Yes and no. All of the
mechanisms we’ve discussed so far do genuinely decrease your cancer risk, but
it’s also important to know that a lot of what we know about how nutrition
influences health comes from association studies. That means researchers look
across a population to see, for example, who eats more fruits, and then figure
out whether those people get fewer diseases like cancer. The trouble is that
people who eat a lot of fruit probably also have other healthy habits, like
exercising regularly, and they’re more likely to be of a higher socioeconomic
status that affords them better healthcare.
This means that only taking
one recommendation is unlikely to have a huge impact on your cancer risk. You
can eat all the strawberries you want, but if you're having bacon every day
you're unlikely to have a healthy colon. And if you're a super-healthy eater,
having a serving of bacon once a week as a treat isn't going to greatly raise
your cancer risk. But if you shift your whole diet toward more fruits, veggies,
whole grains, and low-fat dairy—and away from red or processed meats and
sugar—you have a better chance of staying healthy than if you ate carelessly.
You're even less likely to get cancer if you don't drink alcohol or
smoke, and if you
get plenty of physical exercise.
Of course, many people
follow all these recommendations and still get cancer. And some people will
smoke and drink and eat chocolate bars every day of their lives and die at a
ripe old age without ever developing cancer. It’s important to remember that
neither end of that spectrum means that the recommendations are no good.
Statistically, across an entire population, many tens of thousands fewer people
would get cancer if everyone ate a healthy, balanced diet. And while cutting
down on sugar and upping fiber intake isn't a magical cancer prevention method,
good nutrition definitely won't do you any harm.
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