The World Health Organization recently reported that “processed meat is carcinogenic to humans” and “red meat is probably carcinogenic to humans”, causing a huge uproar in the media. And where there are news reports, there are comments by people only superficially acquainted with the topic.
I’ve seen essentially two types of opinions, both of which completely miss the point (the premise of the first one and the conclusion of the second one are simply wrong):
- “Meat causes cancer, so you should immediately stop eating it.”
- “The increase in the risk of cancer is tiny, so feel free to eat your bacon.”
To understand the situation, let’s take a look at a study that observed almost half a million Europeans for (a median of) 12.7 years and recorded their dietary habits and causes of death.
According to the study, people who ate more than 160g of processed meat (about two sausages) every day were about 74% more likely to die (of any cause) than people of the same age who ate only 10–20g of processed meat, and people who consumed more than 160g of unprocessed red meat (about one half of an average steak in a restaurant) a day were 37% more likely to die.
Of course, you may object that people eating so much meat are likely to lead an otherwise unhealthy lifestyle, such as being obese, drinking too much alcohol, etc. That is partially true, but even when the data were adjusted for body weight, physical activity, alcohol consumption, smoking, and many other factors, eating more than 160g of processed meat still increased the risk of dying by 43% (for unprocessed red meat, the increase was 10%).
In other words, eating just two sausages a day will increase your risk of death by 43% compared to people of the same age, body weight and dietary habits who just eschew said sausages. That’s a bit scarier than 50g of processed meat increasing your risk of colon cancer from 6% to 7%, which is essentially what WHO reported.
The reason is that the risk increases dramatically with the amount of (red or processed) meat consumed, and cancer is by far not the main culprit. Again, adjusted for other factors, eating 160g+ of processed meat daily increases your risk of dying of various causes as follows:
|160g daily intake of processed meat|
increases of the risk of death by …
|Digestive tract diseases*||58%|
* note that in the cases marked by an asterisk, the sample size was too small to be statistically significant.
How much is safe to eat?
Take a look at the following table, which shows the relative increase of all-cause mortality rates based on processed meat intake (adjusted for other factors, such as body weight, physical activity, education, etc.):
|All-cause mortality rate increase caused|
by consumption of processed meat (in g/day)
|0 to 9.9||1%*|
|10 to 19.9||0%*|
|20 to 39.9||3%*|
|40 to 79.9||9%|
|80 to 159.9||20%|
* values marked with an asterisk do not statistically significantly differ from 0%.
It is safe to say that eating less than 40g of processed meat a day (which corresponds to about half a sausage) will have virtually no effect on your risk of dying.
When it comes to red meat, the only group with a risk significantly differing from 0 was the 160g+ group at 10%; eating less than 160g of red meat a day (about half a steak in a restaurant) should not significantly increase the probability that you will die anytime soon.
Be that as it may, it should be noted that increased mortality rates are not the only problem. Saturated fat, found in excess in red meat and processed meats, has been linked to cognitive decline, and processed meat has been linked to other issues that may lead to a lower quality of life, such as diabetes. Since the relationship between meat consumption and other medical conditions is not yet completely understood, caution is still advised, even for low intakes.