Alice Langford, Elina Mir, Megan Cole, Claire Karlsson, and Sage Wylie, National Center For Health Research
You have probably heard it many times already: don’t eat too much red meat or processed foods. But research shows processed red meats, like bacon, hot dogs, and salami are the biggest problem. Here’s why.
Red Meats vs. Processed Red Meats
In 2015, the International Agency for Research on Cancer (IARC) of the World Health Organization concluded that processed meats are a Group 1 carcinogen, which means it causes cancer. Other Group 1 carcinogens include tobacco and asbestos. Based upon a review of over 800 studies, 22 scientists from ten countries determined that processed meats can cause colorectal cancer and probably stomach cancer. Although people who eat more red meat are more likely to develop pancreatic and prostate cancer, nobody knows whether people who eat more red meat tend to have other poor health habits that are the real causes of these cancers, rather than the red meat itself.
Bacon, hot dogs, bologna, and other processed meats are now blamed for causing cancer and increasing your chances of developing heart disease and diabetes. A 2010 study led by Dr. Renata Micha from the Harvard School of Public Health analyzed 20 previous studies and concluded that while eating more red meat didn’t predict whether a person developed heart disease or diabetes, eating processed meat did. A person who ate one portion (about one hot dog or two slices of deli meat) of processed meat every day was 42% more likely to develop coronary heart disease and 19% more likely to develop diabetes than if that person did not eat processed meat every day. That risk was the same if the person ate 2 portions of processed meat every day instead of one, and doubled if the person ate 2 portions a day instead of none. In other words, even if you like the taste or convenience of processed meat, eating less processed meat is always better for your health than eating more.
A 2018 study of more than 100,000 French adults found that those who ate more ultra-processed food were more likely to develop any kind of cancer, and especially breast cancer. The researchers asked participants to complete a diary recording their food consumption for one 24-hour period every 6 months for 2 years, and then followed up with everyone for an average of 5 years to see if they developed cancer. The study is continuing, but so far the researchers report that adults who ate more ultra-processed foods were 12% more likely to develop cancer and 11% more likely to develop breast cancer (especially postmenopausal breast cancer). Although younger, less educated, less physically active adults, and smokers were more likely to eat more ultra-processed foods, the increase in cancer was true for all adults, not only those with those demographic traits and health habits. In addition, the researchers found that the eating more ultra-processed food predicted cancer risk even when they adjusted for BMI. 
A report by the American Institute for Cancer Research and the World Cancer Research Fund revealed that processed meat increases the risk of developing colorectal cancer. The report analyzed 99 studies and described key findings. One finding was that for every 50 grams of processed meat eaten (about one hot dog) colorectal cancer risks increases by 16%. 
Why the Difference?
When comparing red meats with processed meats, there are some key nutritional differences. While levels of saturated fats and cholesterol are usually similar in processed and unprocessed meats, processed meats generally have four times the amount of sodium and 50% more preservatives than red meats. Researchers suggest that these increased levels of sodium and preservatives may explain the increase in health risk. To determine if that is true, further research is needed. What is known, however, is that sodium increases blood pressure and preservatives reduce sugar tolerance. High blood pressure contributes to heart disease and reduced sugar tolerance increases the risk of diabetes. Other studies have found that processed meats that have been cured, smoked and barbecued at high temperatures are more likely to cause colon cancer than other red meats.[ 6] Cured meats like salami may pose particular risks for cancers because the nitrate and nitrite salts used in the curing process can promote cancer cell growth. Yet much more research is needed to clarify how processed meats can lead to cancer.
In addition, a study found an increase in breast cancer for Hispanic women with the highest consumption of processed meat, although that was not found in non-Hispanic white women.
…but don’t pick up that steak so fast.
Does this mean that you are now free to eat all the red meat you want as long as it isn’t processed? Well, no. Studies have shown that red meat raises the level of “bad cholesterol,” because it is high in saturated fat. Chicken and fish are much lower in saturated fat. While processed meat is labeled as a definite carcinogen, red meat is categorized as probably carcinogenic to humans (called Group 2A by IARC). Plus, eating less red meat may help reduce climate change, because cows emits harmful greenhouse gases. Additionally, a study of 150,000 women, published in a major medical journal in 2016, found that eating red meat for protein instead of eating plants increases the chances of developing heart disease and dying at a younger age.
What Meats Should I Eat and What Meats Should I Avoid?
As outlined by the US Department of Agriculture (USDA), consider the following when selecting meats for you or your family:
- Choose lean or low-fat meat and poultry. Avoid ground beef that is less than 80% lean (the leaner, the better). And here’s a surprise: According to a dietitian from the Harvard School of Public Health, chicken skin is a healthy, unsaturated fat that keeps the chicken flavorful.
- If you buy processed meats, be sure to read the Nutrition Facts label to avoid foods high in salt. Products should have no more than 600 mg of sodium per serving. Many delis sell low-salt turkey and chicken. Another option is to bake chicken, ham, or turkey at home to use as “deli” meat. If you are planning to cook out this summer, think about reducing the fat and salt of the foods you grill, by adding more chicken, salmon, or turkey burgers to your menu.
- Consider eating fish rich in omega-3 fatty acids, such as salmon, trout, and herring, or getting protein from other non-meat sources, such as beans, legumes, almonds, sunflower seeds, and egg whites.
Is All Processed Meat Worse than Red Meat?
Processed meats are not necessarily worse than all other red meats, as the “healthiness” of a meat depends upon the number of calories per serving as well as the sodium and fat content. For instance, lean deli meat may be healthier than a fatty unprocessed hamburger or steak. However, in general, bacon, sausage, hot dogs, pastrami, and many other processed meats are fattier, saltier, higher in calories, and contain more additives than unprocessed red meats such as beef, pork, and lamb. Lean and low-sodium varieties of processed meat are less unhealthy, but still not as healthy as most non-processed meats.
The Bottom Line
Foods that are higher in calories, saturated fat, and sodium tend to increase weight, fat, and blood pressure, which in turn, may lead to the development of heart disease and/or diabetes. Eat a balanced diet with plenty of whole grains, fruits, vegetables, low-fat dairy, and lean proteins. Enjoy red meat in moderation and remember: if you have to choose between a hot dog or a hamburger, the unprocessed meat of the hamburger is the safer bet when it comes to avoiding cancer, coronary heart disease and diabetes.
All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.
- Bouvard, Véronique; Loomis, Dana; Guyton, Kathryn Z; Grosse, Yann; El Ghissassi, Fatiha; Benbrahim-Tallaa, Lamia; Guha, Neela; Mattock, Heidi; Straif, Kurt. (October 2015). “Carcinogenicity of consumption of red and processed meat”. The Lancet. DOI: http://dx.doi.org/10.1016/S1470-2045(15)00444-1.
- Micha, R., Wallace, S.K., Mozaffarian, D. (June 2010).“Red and processed meat consumption and risk of incident coronary heart disease, stroke, and diabetes: A systematic review and meta-analysis”. Circulation. 121(21): 2271–2283. doi: 10.1161/CIRCULATIONAHA.109.924977.
- Fiolet T, Srour B, Touvier M, et al. Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort. BMJ (Clinical Research Ed.) [serial online]. February 14, 2018;360:k322. Available from: MEDLINE, Ipswich, MA. Accessed May 21, 2018.
- New colorectal cancer report: Whole grains lower risk, processed meat increases it. American Institute for Cancer Research. http://www.aicr.org/enews/2017/september/enews-new-colorectal-cancer-report-whole-grains-lower-risk-processed-meat-increases.html?utm_campaign=enews&utm_medium=email&utm_source=09072017email. Accessed May 23, 2018.
- Sinha R, Cross AJ, Graubard BI, Leitzmann MF, & Schatzkin A (2009 March 23) Meat intake and mortality: a prospective study over half a million people. Archives of Internal Medicine 169(6):562-571.
- Santarelli, R.L., Pierre, F., Corpet, D.E., (2008). “Processed meat and colorectal cancer: a review of epidemiologic and experimental evidence”. Nutrition and Cancer. 60(2):131-44. doi: 10.1080/01635580701684872.
- Kim, A.E., Lundgreen, A., Wolff, R.K., et al. (2016). “Red meat, poultry, and fish intake and breast cancer risk among Hispanic and Non-Hispanic white women: The Breast Cancer Health Disparities Study.” Cancer Causes Control. doi: 10.1007/s10552-016-0727-4. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/26898200. Accessed on November 13, 2017.
- Powell R (2008) Eat less meat to help the environment, UN climate expert says. Telegraph.
- Song M, Fung TT, et al. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Internal Medicine; 2016.
- Willett W, Miller AM. Ask the Expert: Healthy Fats. Obesity Prevention Source. https://www.hsph.harvard.edu/nutritionsource/2012/06/21/ask-the-expert-healthy-fats/. Published June 21, 2017. Accessed June 8, 2018.
- United States Department of Agriculture (USDA) (2010). Inside the Pyramid (Meat).