Will that bacon strip really put you at risk of cancer?

Joseph Perrone

It’s been a bad week for bacon lovers — headlines around the globe are warning bacon and hot dogs are now considered as big a cancer threat as cigarettes.

The World Health Organization has placed processed meats in a group of substances and occupations considered “carcinogenic to humans,” meaning there’s evidence these items have the potential to cause cancer. Items are added to this grouping based on whether research linking these substances to cancer in humans exists — not by how much of a cancer risk they pose.

For most of the items in this category, scientists have found strong evidence linking them to cancer in humans. There are thousands of studies showing tobacco use, heavy alcohol consumption, mustard gas exposure, etc. can cause cancer. By comparison, the research linking meat consumption to cancer is pretty thin.

In addition to classifying processed meats as “carcinogenic,” the WHO classified red meat (pork, beef, and lamb) as a “probable carcinogen.” This means the WHO thinks red meat might cause cancer in humans, but there isn’t clear evidence. For some context, the WHO also includes shift work (employees switching between day and night shifts) in this category.

Determining whether any single type of food might cause or prevent cancer is incredibly difficult for scientists. Executing a large study in which researchers can control participants food intake over the many years needed to study health effects is virtually impossible. Instead, scientists are forced to rely on observational studies in which they look for associations between what people eat and health outcomes.

These studies cannot determine that eating a certain food causes cancer, only that the participants in their study who ate a certain food developed certain cancers at a higher rate. In the case of meat, the WHO points to a World Cancer Research Fund review of many nutritional studies that concluded those who ate the most processed meat had roughly a 17 percent higher risk of developing colorectal cancer.

What does that increased risk really mean?

As Cancer Research UK breaks down, about 61 out of every 1,000 people will develop colorectal cancer. Using the WCRF study’s estimate, you’d expect 56 cases of colorectal cancer out of 1,000 people who eat low levels of red and processed meats and 66 cases of colorectal cancer out of 1,000 of the highest meat eaters — a difference of only 10 cases per 1,000 people.

Compared to the risk from smoking, the risk of developing cancer from eating too much meat is very small. Tobacco causes an estimated 86 percent of all lung cancers and 19 percent of all cancers.

Reducing your cancer risk starts with a healthy, varied diet with various sources of fruits and vegetables, whole grains and protein, exercising daily and avoiding tobacco. Rest assured, eating the occasional helping of bacon or even a daily serving of lean pork or beef is unlikely to increase your risk of cancer.

Dr. Joseph Perrone is the chief science officer at the Center for Accountability in Science, a project of the nonprofit Center for Organizational Research and Education.