Mythbuster: Does Red Meat Actually Increase Your Risk of Cancer?

Mythbuster: Does Red Meat Actually Increase Your Risk of Cancer?

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There’s a lot of conflicting information out there, so we’re going to review the evidence and help you draw some conclusions.

Important Studies

First, I want to mention a few studies. There are literally hundreds of them out there, so I’m going to mention two prominent meta-analysis that were published within the last 5 years. For those that don’t know, a meta-analysis is the gold standard for combining large amounts of research and drawing conclusions.

Perhaps one of the best studies was published in PLOS one in 2011. In this paper, the authors reviewed 42 articles from 28 prospective studies and combined the data to draw the following conclusions about red meat consumption and the risk of colorectal, colon and rectal cancer. They concluded there was a 22% increased risk of cancer for the highest versus the lowest intake of red meat [RR 1.22 (95% CI = 1.11−1.34)]. There was a 14% increase in risk for every 100 g/day increase intake [RR 1.14 (95% CI = 1.04−1.24)]

Another 2014 meta-analysis that reviewed the publications on Japanese consumption of red meat drew a similar conclusion: “High consumption of red meat and processed meat possibly increases risk of colorectal cancer or colon cancer among the Japanese population”. This association was roughly between 15-23% increased risk (as seen in similar studies)

One of the more well known studies, the European Prospective Investigation into Cancer and Nutrition or EPIC study concluded that “reduction of processed meat consumption to less than 20 g/day could prevent about 3% of all deaths” globally.

Most studies have focused on colorectal colon and rectal cancer. There is some research, with generally less clear conclusions, linking red meat consumption to prostate, pancreatic, bladder, esophageal, lung, kidney, and stomach cancer.

It is worth noting that there are some studies that find no association and others that find a stronger association between red meat consumption and cancer risk. However, the majority tend to find a loose association of around a 20% increased risk.

Other Compounding Factors

There is also research that the presence of poor dietary and other lifestyle choices actually increase your risk for colorectal cancer more so than the red meat consumption itself. Most of the studies note that folks who consume red meat also consume too many calories, eat fewer fruits and vegetables, are more obese, exercise less, and have higher rates of alcohol and tobacco use.

Suggested changes from these studies include:

  • Increase your intake of fish, poultry, vegetables, fruits, and grains
  • Avoiding tobacco use
  • Avoiding alcohol consumption,
  • Weight loss and obesity reduction,
  • Increased physical activity, and
  • Maintaining adequate sleep patterns

What is the proposed cause?

It’s not entirely clear why red meat increases your risk of cancer. The risk is seen whether the meats are processed or unprocessed, and cooked or uncooked, although there is some variability to the degree of risk.

One proposed cause is certain compounds that are known to be pro-carcinogenic which are either found in red meat or produced during preparation and cooking. This includes:

  • Heterocyclic Amines,
  • Polyaromatic Hydrocarbons, and
  • Nitrosamines

I will add that these products are not exclusive to red meat, but are likely found in higher concentrations, especially depending on preparation.

More recently, researchers have proposed another mechanism. A sugar like molecule found in red meat, called N-Glycolylneuraminic acid or Neu5Gc for short, has been linked with inflammation and liver cancer in mice. This mechanism is quite novel, and the research is limited, so stay tuned.

Criticism of Research & Skepticicism

There are still a lot of people out there who aren't convinced there is any concrete evidence stating that red meat truly increases your cancer risk. By nature of the type of science, we can’t do prospective case-control randomized trials, so the research is strictly observational and can’t prove causality. Subsequently there are many strong criticisms of the available research, for example:

  • Weakly positive associations that are often not statistically significant (although this is definitely not true across the board)
  • Insufficient follow up
  • Lack of understanding of mechanism(s)
  • No universal definition of ‘red meat’ from study to study
  • Lack of control of confounding variables (smoking, weight, diet, exercise, etc)

References

Chan DSM, Lau R, Aune D, Vieira R, Greenwood DC, Kampman E, et al. (2011) Red and Processed Meat and Colorectal Cancer Incidence: Meta-Analysis of Prospective Studies. PLoS ONE 6(6): e20456. doi:10.1371/journal.pone.0020456

Ngoc Minh Pham et al. Meat Consumption and Colorectal Cancer Risk: An Evaluation Based on a Systematic Review of Epidemiologic Evidence Among the Japanese Population Jpn. J. Clin. Oncol. (2014) 44 (7): 641-650 first published online May 19, 2014 doi:10.1093/jjco/hyu061

Rohrmann S, Overvad K, Bueno-de-Mesquita HB, et al. Meat consumption and mortality - results from the European Prospective Investigation into Cancer and Nutrition. BMC Medicine. 2013;11:63. doi:10.1186/1741-7015-11-63.

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