The link between colon cancer and meat consumption has been trumpeted by vegetarians and refuted by paleo fanatics. My question, as usual, is: “What role does genetics play?”
The World Health Organization includes processed meat on their list of probable carcinogens. This is based on several large epidemiological studies that show processed meat consumption increases colon cancer risk by 18-20%!
Putting the statistics into perspective:
According to the American Cancer Society, the lifetime risk of colon cancer is around 5%, and increasing that risk by around 20% would give a lifetime risk of about 6%.
This statistical risk is based on epidemiologic studies of the population as a whole and doesn’t take into account individual genetic variants that can increase – or decrease – the risk of colong cancer..
A 2014 study looked at the interaction between genetics and the risk of colon cancer from processed meat. Researchers examine the genes of 9,000 colon cancer patients and 9,000 control subjects without colon cancer.
Researchers discovered the increase in colon cancer was linked to the GA/TA3 gene. This gene codes for a transcription factor involved in inflammation and blood vessel epithelial cells. High processed meat consumption in people with GA/TA3 genetic variants increased colon cancer cases.[ref]
Check your 23andMe results for rs4143094 (v.5 only):
- T/T: higher risk of colon cancer with increasing meat consumption
- G/T: higher risk of colon cancer with increasing meat consumption
- G/G: normal
Check your 23andMe results for rs1269486 (v.4 only):
- A/A: higher risk of colon cancer with increasing meat consumption
- A/G: higher risk of colon cancer with increasing meat consumption
- G/G: normal
The increase in the risk of colon cancer for those with the risk allele did vary by the amount of meat consumed. Carriers of the risk allele who ate the highest percentage of meat had a 39% increased risk for colon cancer; carriers who ate less meat were at a 20 – 26% increase in risk.
People who carry the normal genotype, which is about 60% of Caucasians and 90% of Chinese populations, were not found to have an increased risk of colon cancer with meat consumption.
Statistically, this actually makes sense with the population-wide studies that showed Americans overall to be at an 18% increased risk of cancer with meat consumption. And this is why population-wide recommendations for diet are often misleading — or completely wrong.
The lifehacks here are obvious! If you carry the risk alleles – especially if you have a family history of colon cancer – cut down on the processed meats.
Examples of processed meats include:
- lunch meat,
Instead, opt for some veggies along with meat or protein sources that aren’t fermented, smoked, or processed in other ways.
Finally, just for all the Parks and Recs fans who always think of Ron Swanson when they hear the word ‘meat’:
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