 In 1969, a correlation analysis performed by 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's a significant correlation between high consumption of cholesterol-containing food items and the worldwide 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 rises, are therefore constantly exposed to fecal cholesterol. Should a cancerous or pre-cancerous 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 a 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, knee, bladder, and bone marrow, non-Hodgkin's lymphoma. So the flip side 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 diets rich in meat, dairy, products, and 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% for every 100 milligrams extra a day. So like a daily omelet, it might increase cancer risk by about 20%. 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% for every 100 milligrams of cholesterol, so that would be like 30% higher risk of pancreatic cancer for a daily omelet. And finally, throat cancer. Increased risk was observed for elevated cholesterol intake, about 85% 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. The elevated cholesterol intake could just be a stand-in indicator that a diet rich in meat, eggs, and dairy products may have unfavorable effects.