Updated on March 29, 2024.
If a juicy bacon cheeseburger is part of your regular diet, 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, a digestive cancer that affects the large intestine and rectum (the last several inches of the large intestine). In 2015, the International Agency for Research on Cancer (IARC), an agency of the World Health Organization (WHO), released an important 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 substance, and red meat as a probable carcinogen.
Since then, more research has supported these findings. For example, total consumption of these types of meats was “significantly” linked to greater colorectal cancer risk in a 2021 study published in the European Journal of Epidemiology. The meats were also deemed major risk factors for early-onset (which develops at a younger age) colorectal cancer in a 2022 study published in BMC Cancer.
But colorectal cancer isn’t the only cancer connected to meat consumption. Results from one review published in 2018 in the International Journal of Cancer 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 cancers of the stomach, bladder, endometrium (the lining of the uterus), esophageal (the tube that connects the mouth to the stomach), prostate (a male reproductive organ that sits below the bladder and produces semen), 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 red meat-cancer connection
While research suggests an association between red meat and cancer, more evidence is still needed to confirm a definite cause and effect. A number of theories have been proposed for this connection, and one widely accepted idea is that red meat may become carcinogenic (produce cancer-causing substances) when 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 over an open flame. These chemicals may contribute to changes in DNA in the human body, which in turn may 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 processed meat-cancer connection
Processed meats are linked to cancer 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 chicken, fish, 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.
Increasing your intake of plant-based foods is also a healthy option. The ACS recommends eating a variety of colorful vegetables and fruits each day, and choosing whole-grain foods like whole-wheat 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 in your diet, 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.
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.
Enjoying foods in moderation is also important.
“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 [which are solid at room temperature, like butter], and have some days where you're not eating meat at all.”
If you’re looking for a 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 says it's a way to incorporate healthy plant-based proteins into your diet and to increase your intake of vegetables, whole grains, and fruit. The Meatless Monday website offers recipes, restaurant ideas, and testimonials for people looking for extra tips or encouragement.
