Meat, Dairy, and Prostate Cancer 11-01-08

by Jon Barron

New research out of the University of Oxford in England has confirmed a strong link between eating meat and dairy and the development of prostate cancer. The research examined the results of 12 previous studies involving 9,000 men. According to the researchers, those men who ate large amounts of meat and dairy showed elevated levels of Insulin-like Growth Factor-1 (IGF-1), a hormone that promotes cell growth and inhibits the removal of degenerated cells. The study concluded that high levels of IGF-1 raised the risk of prostate cancer by up to 40 percent. Also, according to lead researcher Andrew Rodham, elevated levels of IGF-1 not only lead to an increased risk for developing cancer, but also aid the spread of tumors once the disease has developed.

Well, they got it half right. The fact that eating large amounts of commercial meat and dairy increases your risk of cancer is true, but hardly revolutionary. I've talked about this repeatedly over the years (more in a minute). On the other hand, the researchers' statement that IGF-1 increases the risk of cancer may ultimately prove true -- but for now involves a giant leap in logic.

Yes, there are indeed some studies that suggest that IGF-1 stimulates the growth of prostate tissue. But there are indeed many other studies that have proved the opposite -- that IGF-1 and prostate cancer are not connected. But studies aside, simple observation confounds that conclusion. Consider that the incidence of prostate cancer increases as men age, yet blood levels of IGF-1 decline significantly with age, about 14% per decade after age 30. This is the exact opposite of what the researchers suggest. It therefore seems highly unlikely that IGF-1 would have any causative relationship with prostate cancer.

So what is about eating meat or dairy that might account for the increased risk of cancer?

Actually, before we go there, let's quickly take a look at some other studies that show the same increased risk for other forms of cancer.

* Here's a large-scale study from last year that shows that eating beef and processed meats sharply increases the risk of colon, lung, and other cancers.
* And here's one from two years ago that demonstrates the connection between breast cancer and meat.
* And here's one that shows the connection between a typical high meat Western diet and colon cancer.

You get the idea. By the way, an interesting side note is the consistent equivocating of the researchers when it comes to drawing conclusions about meat and dairy after conducting their studies. For example, Debbie Clayton, of the Prostate Cancer Charity, commented on the prostate study results: "More research is needed... before this can be translated into useful advice for men on which foods may need to be modified in their diet." And a spokesperson for the agency that funded the study, Dr. Leslie Walker of Cancer Research UK, also exercised caution: "While there are established risk factors associated with prostate cancer of age, family history, and ethnicity, there are no clear data on modifiable risk factors."

No clear data? It seems pretty obvious in reviewing the data that meat and dairy don't exactly lead to cancer immunity and that it would be wise to cut down on the burgers and cheese. As for Ms. Clayton's comment about it being unclear as to "which foods may need to be modified," perhaps a child in elementary school could draw up a list of the foods that fall into the "meat" and "dairy" categories. But enough of that. The question at hand is: If not IGF-1, then what might account for the increased cancer risk involved in consuming meat and dairy?

The first answer can be seen in some of the studies I've already cited. High heat and charring of meat dramatically increases the risk of cancer. And we also know that eating more than 3oz of meat a day alters the intestinal bacteria -- significantly escalating E. coli populations in the colon. In fact, a new study released just yesterday found that diets high in red meat and dairy increase the presence of a sugar molecule called N-glycolylneuraminic acid (Neu5Gc), which provides a toe hold for a toxin released by E. coli in the intestinal tract. But neither of those reasons explain dairy's connection to cancer. So once again, the question is what do meat and dairy share in common that would account for the increased cancer risk?

And the most likely answer can be found in what's added to both meat and dairy -- antibiotics and growth hormones.

Antibiotics are added to animal feed to prevent the rapid spread of bacterial infection among thousands of animals kept in close quarters. This means that virtually all of the meat and dairy that you eat (other than organic) is loaded with antibiotics, which destroy ALL of the beneficial bacteria in your gastrointestinal tract. This matters because beneficial bacteria account for almost 60% of your immune function, and cancer is fundamentally a disease of the immune system.

As for growth hormones, synthetic versions are added to animal feed to increase both meat and dairy production. And synthetic growth hormones have been proven to increase the risk of cancer. Oh by the way, synthetic growth hormones significantly increase IGF-1 production, thus accounting for the high IGF-1 levels found in these study. But remember, IGF-1 production normally goes down as prostate cancer goes up. It would appear then, that the problem is not the IGF-1 itself, but rather the way it is introduced to the body -- naturally as produced by the body itself which does not present a problem, or as a synthetic additive in the diet which does.

So what to do while waiting for researchers to sort everything out?

* Reduce your consumption of meat and dairy. Consume three ounces a day of meat a day or less. Do not consume it unless it is raw and organic.
* If you do consume either, use only organic without added antibiotics and growth hormones. And if you must have dairy, go for raw.
* Avoid charring your meat -- or if you do, make sure you marinate it fully before cooking since marinating significantly reduces the risk.