Updated on May 4, 2023.
If a juicy bacon cheeseburger is still part of your regular menu, you may want to reconsider. A growing body of research suggests that eating processed meats such as sausage and ham—as well as red meats like steak and ground beef—may increase your risk for a variety of cancers.
The evidence is perhaps strongest for colorectal cancer. In 2015, the International Agency for Research on Cancer (IARC), an agency of the World Health Organization (WHO), released a landmark report that found:
- Eating more than 100 grams of red meat per day—a serving about the size of a deck of cards—was associated with a 17 percent higher risk for colorectal cancer.
- Eating more than 50 grams of processed meat per day—roughly two pieces of bacon—was linked to an 18 percent higher risk.
Based on the report, the IARC designated processed meat as a carcinogen, or cancer-causing agent, and red meat as a probable carcinogen.
Since then, several reviews and studies have supported these findings. For example, total intake of these types of meats was “significantly” linked to greater colorectal cancer risk in a 2021 review and meta-analysis published in the European Journal of Epidemiology. The meats were also deemed major risk factors for early-onset colorectal cancer in a 2022 review and meta-analysis published in BMC Cancer.
But colorectal cancer isn’t the only cancer connected to meat consumption. One International Journal of Cancer review published in 2018 suggested that eating a lot of processed meat was associated with a 9 percent higher risk of breast cancer. A study of 42,000 women published two years later in the same journal found those who ate the most red meat had a 23 percent higher risk of developing breast cancer than those who ate the least.
Researchers have also found that people who eat red and processed meats have higher odds of developing stomach, bladder, endometrial, esophageal, prostate, and lung cancer. The risk of cancer death is higher, as well.
What meats are considered to be red or processed?
Beef, veal, pork, lamb, mutton, horse, and goat are all considered to be red meats. Processed meats have gone through preservation or flavoring processes like salting, curing, fermentation, and smoking. These include hot dogs, ham, bacon, deli meats, sausage, corned beef, beef jerky, and meats that are canned or prepared in sauces.
The meat-cancer connection
While links have been drawn between red meat and cancer, more evidence is still needed to confirm a definite cause and effect. What is it about red meat that might lead to cancer? A number of theories have been proposed, but one widely accepted idea is that red meat becomes carcinogenic when it’s cooked at high temperatures.
“Cooking red meat forces the iron—or heme—portions of the meat to convert into compounds that are potentially carcinogenic,” says Ashley Jeter, MD, hematologist and oncologist at Charleston Oncology in South Carolina. In particular, chemicals known as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) form when meats like beef and pork are cooked on an open flame. These chemicals may contribute to changes in DNA in the human body, which in turn increase cancer risk.
Meats cooked for a long period of time and those cooked above 300°F are also susceptible to HCA formation. That usually means anything grilled or fried. Any meats cooked to a well-done temperature can have higher amounts of HCAs, while any type of smoke exposure during cooking can encourage PAHs to form, as well.
The perils of processed meats
Processed meats are potentially dangerous for somewhat different reasons. These foods can contain sodium nitrite, an additive meant to preserve meat while stabilizing its color and flavor. Though nitrites are also found in other types of packaged and canned foods, the nitrites in processed meats can turn into N-nitroso compounds (also known as nitrosamines) when cooked at higher temperatures. These compounds have been proven to be carcinogenic.
Conclusive evidence shows that processed meats do in fact increase the risk of colorectal cancer, but more research is needed to clarify the link between processed meat and stomach cancers.
Overall, when it comes to colorectal cancer, the evidence supporting the increased risk from eating too much processed meat is stronger than the evidence supporting the increased risk from too much red meat.
Are these meats safe to eat in any amount?
The American Institute for Cancer Research recommends that people consume no more than 18 ounces of red meat per week—and that they avoid processed meats altogether. The American Cancer Society (ACS) advises people to limit or cut red meat altogether and choose fish, chicken, beans, and other vegetable protein options instead.
In the 2020 International Journal of Cancer study of 42,000 women discussed above, researchers found that women who ate the most poultry had a 15 percent lower risk of developing breast cancer compared to those who ate less poultry. The researchers concluded that switching from red meat to poultry would also reduce the risk of breast cancer.
You’ve probably also heard that increasing your intake of plant-based foods is pretty much always a good move. The ACS recommends eating a variety of colorful vegetables and fruits each day. You should also choose whole-grain carbohydrates like barley and oats rather than processed foods made from refined grains, such as white bread or breakfast cereal. These healthy diet habits can lower your risk of certain cancers. And if you do choose to include red meat on your menu, the American Heart Association recommends that you bake, broil, roast, or stir-fry rather than frying it, to reduce the level of potentially dangerous byproducts produced during cooking.
Dr. Jeter advises her patients to eat no more than 4 ounces of red meat twice a week and as little processed meat as possible. “If you can eat less than that, that’s great, because we know more than that can be detrimental to your overall health,” she explains.
Perhaps the most important takeaway? Moderation.
“Having healthy limitations on your diet is a good idea anyway,” says Jeter. “Increase your intake of healthy fruits, vegetables, and fiber, limit saturated fats, and have some days where you're not eating meat at all.”
If you’re looking for an easy way to skip meat, try joining the Meatless Monday movement, which encourages people to eat vegetarian or vegan foods at the start of each week. Jeter is a fan because it’s a simple way to incorporate healthy plant-based proteins into your diet and to increase your intake of veggies, whole grains, and fruit. The Meatless Monday website offers recipes, restaurant ideas, and testimonials for people looking for extra tips or encouragement.
