Can Eating Red and Processed Meats Really Cause Cancer?
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Can Eating Red and Processed Meats Really Cause Cancer?

We asked an expert to weigh in on the facts.

Eating processed meats like sausage and bacon, and red meats like steak and ground beef, may increase your risk for colorectal cancer and possibly a few other cancers, according to the World Health Organization (WHO).

In October 2015, the WHO reported that it reviewed more than 800 studies and found that eating more than 100 grams of red meat per day—equivalent to a steak about the size of a deck of cards—was associated with a 17 percent higher risk of colorectal cancer.

The report also found that people who ate more than 50 grams of processed meat per day—roughly two pieces of bacon—increased their colorectal cancer risk by 18 percent.

More recently, an International Journal of Cancer analysis released in October 2018 suggested that high levels of processed meat consumption is associated with a 9 percent higher risk of breast cancer. Other research has revealed links between eating red meat and increased risks of pancreatic, advanced prostate and stomach cancers, says Ashley Jeter, MD, hematologist and oncologist at Charleston Cancer Center in South Carolina. WHO experts said that more research is needed to fully understand these associations.

What meats are classified as red and processed?
Beef, veal, pork, lamb, mutton, horse and goat are all considered 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
The WHO panel concluded that the evidence was sufficient enough to support a link between processed meat and cancer in humans, since there is evidence establishing cause and effect. Meanwhile, they determined that while positive associations have been made between red meat and cancer, more evidence is still needed to confirm a definite cause and effect.

So what it is it about red meat that might lead to cancer? One theory 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 Dr. Jeter. 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 which in turn increase cancer risk.

Meats cooked for a long period of time are also susceptible to HCA formation, as well as any meats cooked above 300 degrees Fahrenheit. 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 dangerous for somewhat different reasons. These types can contain sodium nitrite, an additive meant to preserve the meat and stabilize the color and flavor. While nitrites are also found in other types of packaged and canned foods, the nitrites in processed meats can turn into N-nitroso compounds (or nitrosamines) when cooked at higher temperatures, and these compounds have been proven to be carcinogenic.

Conclusive evidence shows that processed meats do in fact increase risk for colorectal cancer, but more research is needed to clarify the link between processed meat and stomach cancers.

Overall, the evidence that shows processed meats increase colorectal cancer risk is stronger than the evidence that shows red meat may increase the risk of colorectal cancer.

So 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 avoid processed meats altogether. The American Cancer Society (ACS) says people should limit their red meat intake and choose fish, chicken, beans and other vegetable protein options instead.

If you do prepare meats, poultry or fish, consider steaming, baking, boiling or poaching as much as possible, rather than broiling, frying or grilling. The ACS also suggests eating at least two and half cups of veggies and fruits per day, and whole-grain carbohydrates, like breads, pasta, barley and oats, rather than carbohydrate foods made from refined grains. These healthy diet habits can lower your risk of certain cancers.

Jeter recommends that her patients eat no more than four 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 is key.

“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 big 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. You can also try these vegetarian meal ideas to help you implement Meatless Mondays in your household.