Does Eating Meat Cause Cancer?

The claim that processed meat causes cancer is a stretch. It’s a misleading, incomplete claim at best. The claim that red meat causes cancer is false. Here’s a look at the facts…

From the World Health Organization (Please go read for yourself!)

Q: “Could you quantify the risk of eating red meat and processed meat?

The consumption of processed meat was associated with small increases in the risk of cancer in the studies reviewed. In those studies, the risk generally increased with the amount of meat consumed. An analysis of data from 10 studies estimated that every 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by about 18%.

The cancer risk related to the consumption of red meat is more difficult to estimate because the evidence that red meat causes cancer is not as strong. However, if the association of red meat and colorectal cancer were proven to be causal, data from the same studies suggest that the risk of colorectal cancer could increase by 17% for every 100 gram portion of red meat eaten daily.”

Practical Interpretations:

Processed Meat:

As per this article from the American Cancer Society, the “consumption of processed meat”, which is defined as “every 50 gram portion of processed meat eaten daily” and is equivalent to “about 4 strips of bacon or 1 hot dog (EVERY DAY!)”, means a person’s risk of colorectal cancer (not ALL cancer) increases by 18%, which is the RELATIVE RISK, which means its’ 18% of the given/established risk for a population, which in this case “the lifetime risk of someone developing colon cancer is 5%”. SO, an 18% increase on 5% baseline risk, raises one’s risk from 5% to 5.9%.

Red Meat:

Despite considering “the evidence that red meat causes cancer is not as strong”, IF the evidence was strong (ie “causal”), then the 17% RELATIVE RISK of colorectal cancer would raise from 5% to 5.85%… if you ate 100 grams of red meat EVERY DAY.

Ok, let’s review the essential facts here:

1) If you eat about 4 strips of bacon or 1 hot dog (or the 50 gram equivalent of similar processed meat) EVERY DAY (and for exactly how long we don’t know!), your risk of colorectal cancer goes up from 5% to 5.9%.

And:

2) If you eat a small red meat burger (similar in size to a basic McDonald’s burger) EVERY DAY, your risk of colorectal cancer (not ALL cancer) might go up from 5% to 5.85%, BUT since we actually can’t determine that the risk definitely does go up, because the evidence of a causal relationship between cancer and red meat is insufficient, we can’t say for sure that the risk of colorectal cancer goes up from eating red meat.

So it would definitely be false to generalize and conclude from this that “eating meat causes cancer”…

Just think about what the facts say compared to the general claim that “eating meat causes cancer”. In addition to the fact that the relative risk is negligible, it is hardly accurate to say that processed meat causes cancer because:

1) It only increases the risk of colorectal cancer.

2) The increased risk is contingent upon eating processed meat every day. The official WHO explanation (as noted above) states “eaten daily”. How many people actually eat processed meat every day!? Definitely not most of us, yet the conclusion is presented in a such a general way as if the risk is the same for anyone who consumes processed meat period.

3) As so many interpretations of epidemiological studies fail to do, the WHO conclusion doesn’t detail a minimum time span for daily consumption for the risk to apply. In other words, over what period of time does a person have to eat processed meat every day for the risk to go up from 5% to 5.9%? Does the risk apply after one week? Or after 10 years, or longer? And if you stop eating processed meat, is the risk immediately eliminated? Or does the risk remain and, if so, to what extent and for how long?

Perhaps the main takeaway from all this:

It’s very important to understand risk in relative terms.

When you hear in the news something like, “A new study shows that doing X increases the chance of Y happening by 30%”, all this means is that if the baseline chance of Y happening at all is 1% then, assuming the research is legitimate, when X occurs the risk of Y occurring goes up from 1% to 1.3% (which of course is insignificant for almost all of us, yet it’s presented as if it’s a very significant finding).

Further consideration is almost always warranted when anyone makes a general claim about risk, but especially when a claim about risk is made in the media and especially when it’s based solely on an epidemiological study. Epidemiological studies involve populations and thus, to put it mildly, they are inherently limited in their capacity to determine the actual risk of an individual.