No colon cancer in the Stone Age?

Philip J. Goscienski, M.D.

June 2006

Cancer of the colon is largely a lifestyle disease even though some types have a familial tendency. Just because you have a genetic disposition toward colon cancer doesn't mean that it's inevitable.

Did Stone Age folks get colon cancer? It's a good bet that those who lived in the Old Stone Age, the 2 million years before the Agricultural Revolution, rarely developed this form of cancer and it's not because they didn't live long enough. Fossil studies show that about 10 percent of those who lived back then made it past 60 years of age. They avoided this and other forms of cancer because they had a high intake of fruits and vegetables and a low intake of red meat.

A low intake of red meat? That sure doesn't fit the picture most people have of rugged, well-muscled hunters chasing down a panicky mammoth. The reality is that for most of humans' existence they had neither sophisticated weapons nor well-developed hunting skills. Their meat came from small game, chicks not yet hatched from eggs and the abandoned kill of other animals. (My apologies to the queasy reader.)

Physicians have known for decades that persons who eat lots of fruits and vegetables have low rates of colon cancer and they assumed that it was the fiber content. That doesn't account for all the protective effect. A better explanation might be that natural salicylates, which are chemically related to common aspirin, inhibit growth factors that encourage cells in the colon to become cancerous. Plant foods are also loaded with antioxidants that protect cells from DNA damage that leads to cancer.

What Stone Agers didn't eat also helped to protect them from colon cancer. Most Americans have some form of processed meat (hot dogs, bologna, salami, etc.) every week and it's the nitrites in these foods that have been linked to colon cancer.

Cooking meat at high temperatures yields substances called nitrosamines whose cancer-causing potential has been known for years. The higher the temperature, the more likely the formation of nitrosamines. Cooking was a rather late cultural development and probably arose no earlier than 200,000 years ago, so for most of our history humans avoided this major risk factor.

Prehistoric humans avoided another factor that is clearly linked to colon cancer, namely, obesity. It's not clear whether it is an increase in body fat, a high intake of refined carbohydrate or a decrease in physical activity that is to blame since the three are so closely related but the association is indisputable. In addition, there were no "adult beverages" during the Old Stone Age. Even moderate alcohol intake doubles the rate of colon cancer.

We have one advantage that Stone-Agers never had: medical screening tests for colon cancer. As uncomfortable as it sounds (and is), a rectal exam has been literally lifesaving for thousands of patients whose early cancer was within reach of the examiner's fingertip. During that same procedure the physician can check for the invisible amount of blood that is another sign of possible cancer.

Most cancers of the colon are beyond the reach of the examining physician but not beyond the reach of a flexible tube called the colonoscope. Cancer specialists suggest a screening colonoscopy at age 50 for everyone and earlier for those with a family history of colon cancer. Sure, it's uncomfortable, but so is terminal cancer.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.