Why Are Eggs Linked to Cancer Progression?
About two million men in the U.S. are living with prostate cancer, but that’s better than dying from prostate cancer. Catch it when it’s localized and your 5-year survival is practically guaranteed, but once it really starts spreading your chances drop to 1 in 3. So Harvard researchers took more than a thousand men with early stage prostate cancer and followed them for a couple years to see if there was anything in their diet associated with a resurgence of the cancer, such as spread to the bone.
Compared to men who hardly ate any eggs, men who ate even less than a single egg a day had a significant 2-fold increased risk of prostate cancer progression. The only thing worse was poultry (with skin) consumption, which showed up to 4 times the risk of progression among high-risk men. Researchers believe the higher risk might be caused by the cooked meat carcinogens, heterocyclic amines that build up more in chicken and turkey muscle than in other meats.
But what about the eggs? Why would less than once a day egg consumption double the risk of cancer progression? The Harvard paper suggests that the choline in eggs may increase inflammation.
As I explained in my video Carnitine, Choline, Cancer and Cholesterol: The TMAO Connection, eggs are the most concentrated common source of choline in the American diet, which may increase the risk of cancer emergence, spread, and lethality. Another Harvard study, entitled Choline Intake and the Risk of Lethal Prostate Cancer, found that those with the highest choline intake had a 70% increased risk of fatal prostate cancer. Another recent study found that men who consumed 2 and a half or more eggs per week—that’s just like one egg every three days—had an 81% increased risk of lethal prostate cancer.
In the New England Journal of Medicine the same Cleveland Clinic research team that performed the famous study on carnitine (see my last Care2 post Avoid Carnitine and Lethicin Supplements), tried feeding people hard-boiled eggs instead of steak. As they suspected, the egg-eaters experienced a spike of the same TMAO compound associated with red meat consumption (and strokes, heart attack, and death).
It’s ironic that the choline content of eggs is something the egg industry actually boasts about. And they are aware of the cancer connection. Through the Freedom of Information act I was able to get my hands on an email (displayed in the above video) from the executive director of the industry’s Egg Nutrition Center to an American Egg Board executive talking about how choline may be a culprit in promoting cancer progression: “Certainly worth keeping in mind as we continue to promote choline as another good reason to consume eggs.”
Michael Greger, M.D.