"Dietary Cholesterol and Cancer"
In 1969, a correlation analysis performed by a Dr. Gregor
(no relation, and he spelled it wrong),
found this rather tight correlation between animal protein intake
in countries and intestinal cancer mortality.
In the ‘70s this relationship was extended to breast cancer too,
and animal fat implicated as well,
but it all kind of travels together in the same foods,
along with dietary cholesterol.
“And there is significant correlation between high consumption of
cholesterol-containing food items and
the world-wide distribution of colon cancer” as well,
a large and highly significant correlation
even after controlling for other dietary factors
such as animal fat and fiber, supporting the possibility of
a cause and effect relationship between cholesterol intake and colon cancer.
So, is dietary cholesterol co-carcinogenic for human colon cancer?
Let’s find out by feeding some to rats.
Inject rats with a carcinogen and cholesterol-eating rats
get tumors in half the time and all die off,
whereas most of the cholesterol free group survives.
But “the relevance of animal data to the human situation is debatable.”
How would the cholesterol and cancer link even work?
Well, we don’t need to consume any cholesterol,
since our body makes all that it needs,
and when we do consume extra, there’s a limit to the amount
of cholesterol the body can absorb.
So where does the excess go?
Down to our colon, and so the cells lining our colon,
where colon cancer arises, are therefore constantly exposed
to fecal cholesterol.
Should a cancerous or precancerous polyp arise,
maybe all that extra cholesterol would help it grow faster?
The amount of cholesterol we eat could
“thus be a factor determining the rate of
development, growth, or spread of such a tumor.”
This was all just kind of speculation back in the 70s,
but they realized that if it were true,
that would be good news, since a low cholesterol diet,
cutting down on meat, dairy, eggs, and junk—
the only foods that really have cholesterol—
would be a feasible, cheap, safe way to help
prevent and treat colon cancer.
So, what’s the 40-year update?
Country-by-country correlation can never do more
than just inspire studies like this,
“the largest nationwide population- based case–control study [to date]
to assess the association between cholesterol intake
and several types of cancer.”
And, they found…
dietary cholesterol intake was associated with increased risk
of cancers of the stomach, colon, rectum, pancreas, lung, breast,
kidney, bladder and bone marrow—non-Hodgkin’s lymphoma.
So, the flipside is that “a diet low in cholesterol
may play a role in the prevention of several cancers.”
What does that mean food wise?
Cutting down on meat, dairy, and eggs,
which may increase risk of cancer, though eating diaries,
would probably just increase risk of paper cuts—
lots of fiber though!
“The findings of this study should essentially be viewed
as an indication that a diet rich in meat, dairy products, eggs…
is an unfavorable indicator of the risk of several common cancers.”
Two cancers they didn’t look into, though,
were endometrial cancer and throat cancer.
Put all the studies on cholesterol consumption
and the risk of endometrial cancer together—
cancer of the lining of the uterus—
and they found a dose-response, meaning more cholesterol consumption
associated with more cancer, 6 percent for every 100 mg extra a day;
so, like a daily omelet might increase cancer risk by about 20 percent,
maybe because the extra cholesterol is converted into estrogen,
or it may just be the increased oxidative stress
reflected in higher levels of oxidized cholesterol?
I talk about that in my Alzheimer’s series.
There also appears to be a dose-response relationship
with pancreatic cancer, one of our most dismal malignancies.
The compilation of studies found the risk increased by 8 percent
for every 100 mg of cholesterol;
so, that would be like 30 percent higher risk
for pancreatic cancer for a daily omelet.
And finally, throat cancer.
Increased risk was observed for elevated cholesterol intake.
About 85 percent higher odds, consistent with the other studies.
Yeah, maybe it’s the oxidation, but maybe it’s the inflammation.
However, we can’t be sure it’s the cholesterol itself that’s to blame.
“Elevated cholesterol intake could [just be a stand-in] indicator
that a diet rich in meat, eggs, and dairy products
may have unfavorable effects.”