Dietary Cholesterol and Cancer

Dietary Cholesterol and Cancer

August 19, 2019 97 By William Morgan


“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.”