Does eating meat put you at a higher risk for colon cancer?

Recent headlines have touted that meat consumption causes colon cancer. This, of course, has set off Twitter wars between meat lovers and vegetarians, with most people left wondering how this personally affects them. Should they eliminate red meat from their diet? What is the true risk of colon cancer due to meat consumption?

Colon cancer, red meat, and personalized nutrition:

In 2015, the World Health Organization included processed meat (e.g. sausages, ham, hot dogs, beef jerky) on its list of probable carcinogens.[ref] The listing is based on several large epidemiological studies that show processed meat consumption increases the relative risk of colon cancer by 18-20%.

For example, a meta-analysis combining data from 42 studies determined that consumption of processed meat increased colon cancer risk by 20%. [ref]

Putting the risk 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%. [ref]

Importantly, this statistical risk is based on epidemiological studies of the population as a whole. It doesn’t take into account individual genetic variants that can increase – or decrease – the risk of colon cancer.

When you bring individual genetics into the picture, it turns out that for some people, meat consumption probably doesn’t increase the risk of colon cancer at all.  For other people, the increase in risk is quite a bit higher than the 20% increase.

Genetics and colon cancer risk:

A 2014 study looked at the interaction between genetics and the risk of colon cancer from processed meat intake. Researchers examine the genes of 9,000 colon cancer patients and 9,000 control subjects without colon cancer. They discovered that there was a significant diet-gene interaction between the GATA3 gene variants and colon cancer risk when stratified by meat consumption (processed meat and red meat). [ref]

Another study found that a genetic variant in the CCAT gene normally decreased the risk of colon cancer, but in conjunction with a high intake of processed meat, that protection was eliminated. [ref]


Genetic variants that increase the risk of colon cancer due to meat consumption:

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GATA3 Genetic Variants:

Researchers discovered the increase in colon cancer was linked to the GATA3 gene. This gene codes for a transcription factor involved in inflammation in the epithelial cells that line your blood vessels.

High processed meat consumption in people with certain GATA3 genetic variants increased colon cancer cases significantly.[ref]

Check your genetic data for  rs4143094 (23andMe v5; AncestryDNA):

  • T/T: higher risk of colon cancer with increasing meat consumption (~40% increased relative risk)
  • G/T: higher risk of colon cancer with increasing meat consumption (~20% increased relative risk)
  • G/G: typical (no increased risk of colon cancer with processed meat consumption)

Members: Your genotype for rs4143094 is .

Check your genetic data for rs1269486 (23andMe v4; AncestryDNA):

  • A/A: higher risk of colon cancer with increasing meat consumption
  • A/G: higher risk of colon cancer with increasing meat consumption
  • G/G: typical (no increased risk of colon cancer with processed meat consumption)

Members: Your genotype for rs1269486 is .

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 typical 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 makes sense with the population-wide studies that showed Americans overall to be at an 18% increased risk of cancer with meat consumption. This illustrates why population-wide recommendations for the diet are often misleading for an individual.

CCAT genetic variants:

Another study on the link between colon cancer and processed meat consumption found that the CCAT genetic variant also comes into play with meat consumption and colon cancer.

In general, carrying the rs6983267 T-allele is associated with a lower risk of colon cancer, and this protection is further enhanced by the regular use of aspirin. [ref][ref] But, when looking at processed meat consumption of over 25 g/day, that protection in the risk for T-allele carriers was eliminated. [ref]

This is a case where dietary choices eliminates a natural genetic protection against colon cancer.

Check your genetic data for rs6983267 (23andMe v4, v5; AncestryDNA):

  • G/G: normal (higher) risk of colon cancer
  • G/T: somewhat decreased risk of colon cancer — except for people who eat a lot of processed meat
  • T/T: generally a decreased risk of colon cancer — except for people who eat a lot of processed meat [ref]

Members: Your genotype for rs6983267 is .

 


Lifehacks:

If you carry the risk alleles above – especially if you have a family history of colon cancer – consider cutting down on or eliminating processed meats from your diet.

Examples of processed meats include:

  • brats
  • lunch meat
  • bacon
  • pepperoni
  • salami
  • hotdogs

If you do decide to eat processed meats, include vegetables in the meal as well. Several studies have shown that including cruciferous or green vegetables along with meat decrease any negative effects of meat in the colon. [ref]

 

Originally published 1/2018; updated 8/2020



Author Information:   Debbie Moon
Debbie Moon is the founder of Genetic Lifehacks. She holds a Master of Science in Biological Sciences from Clemson University and an undergraduate degree in engineering from Colorado School of Mines. Debbie is a science communicator who is passionate about explaining evidence-based health information. Her goal with Genetic Lifehacks is to bridge the gap between the research hidden in scientific journals and everyone's ability to use that information. To contact Debbie, visit the contact page.