Taking cancer off your shopping list

The World Health Organization (WHO) has made a groundbreaking, and potentially lifesaving, announcement concerning the link between eating meat and the development of cancer. Specifically, WHO researchers (the Working Group) concluded that eating 50 grams (1.8 oz) of processed meats such as bacon, hot dogs, beef jerky, and deli meats per day increases a person’s risk of developing colorectal cancer by 18 percent.

The report mainly focused on processed meats

The researchers classified eating processed meats as “carcinogenic to humans” (Group 1), based on finding sufficient evidence for their causing colorectal cancer. A Group 1 classification places processed meat consumption in the same category as smoking and asbestos. In addition, the Working Group reported a positive association between eating processed meat and stomach cancer.

But it also looked at red meat and cancer in general

To a somewhat lesser but still important extent, the WHO report pointed out that red meat (unprocessed meats), such as beef burgers, lamb chops, and pork roast, are “probably carcinogenic to humans” (Group 2A). When looking at the risk of colorectal cancer in particular, the Working Group reported a 17 percent increased risk associated with 100 grams (3.5 oz) per day of red meat. If people chose to subject these meats to high temperatures such as when frying or barbequing, the risk of cancer may increase, although the authors explained that more research into this topic is needed.

We say “potentially lifesaving” because in order for these significant health warnings to have a positive impact, people need to heed them. It may help to know that these warnings and the recommendations stated in the report are based on the findings of more than 800 studies, which were reviewed by an international team of 22 scientists from ten countries. The studies themselves came from several continents and covered a broad spectrum of diets and ethnicities.

According to estimates by the Global Burden of Disease project, diets high in bacon, sausage, and other processed meats lead to nearly 35,000 deaths from cancer per year. When it comes to red, unprocessed meats, the Working Group noted that if further investigations prove that eating these foods causes cancer, then 50,000 deaths from cancer annually could be attributed to following such a diet.

This WHO report supports and advances the stance of the American Cancer Society, which encourages individuals to consume more vegetables and fish and less processed and red meats. The Society has based this recommendation on “a wealth of studies linking colon cancer to diets high in red meats (beef, lamb, or liver) and processed meats (hot dogs, bologna, etc.).”

What about meat and prostate cancer?

The figures associated with consuming processed and unprocessed meats and development of colorectal cancer are alarming. In fact, according to the American Cancer Society, colorectal cancer is the third leading cause of cancer-related deaths among men and women in the United States, with men being slightly more likely at risk than women. During 2015, an estimated 49,700 people are expected to succumb to the disease.

Although the WHO report did not focus on an association between consumption of processed meat and unprocessed red meat and prostate cancer, this relationship has been studied for many years. Research has explored the impact of the potentially harmful substances in meat (e.g., saturated fat, nitrates and nitrites, hormones) as well as the effect of various cooking methods.

Among those studies are the following:

• A systemic review published in Nutrition & Metabolism (2014) in which the authors stated that “red meat, dietary fat and milk intake should be minimized as they appear to increase the risk of prostate cancer”
• A case-control study (2015) conducted in Pakistan in which the investigators concluded that their findings supported “the hypothesis that frequent consumption of red meat and fat items may increase prostate cancer risk”
• An American Institute for Cancer Research review, in which the authors stated that eating red meat could increase the risk of cancer of the prostate, breast, pancreas, and kidney
• A Harvard University study, in which nearly 15,000 men were evaluated. The authors found that men who ate red meat at least five times a week had a relative risk of 2.5 for developing prostate cancer when they were compared with men who ate red meat less than one time a week.
• A National Cancer Institute study that evaluated the meat eating habits of more than 175,000 men over a nine-year period. The researchers found that “men who ate the most red meat were 12 percent more likely to develop prostate cancer and 33 percent more likely to have advanced cancer than those who ate the least amount of red meat.”
• The National Cancer Institute study also discovered that barbecued and grilled meat were associated with total and advanced prostate cancer, while nitrites and nitrates (in processed meats) were associated with advanced prostate cancer.
• A study conducted by Vanderbilt University and published in Nutrition and Cancer, which reported that high consumption of meat that is well-done and high exposure to heterocyclic amines and other carcinogens in meat may raise the risk of prostate cancer

The takeaway

The WHO report is an international wake-up call for everyone to recognize the cancer risks associated with eating processed meats and red meat in general. Yes, vegetarians get cancer too, but the evidence shows that global communities with the lowest meat consumption have the longest life-spans and the lowest cancer rates. Processed meats should definitely be off your shopping list, especially if you are reading this and are concerned about prostate cancer.

Sources

AICR: World Cancer Research Fund. Food, nutrition, and the prevention of cancer: A global perspective. American Institute of Cancer Research. Washington, DC: 1997

Bashir MN, Malik MA. Case-control study of diet and prostate cancer in a rural population of Faisalabad, Pakistan. Asian Pacific Journal of Cancer Prevention 2015; 16(6): 2375-78

Bouvard V et al. on behalf of the International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of consumption of red and processed meat. The Lancet Oncology published online 26 October 2015

Gann PH et al. Prospective study of plasma fatty acids and risk of prostate cancer. Journal of the National Cancer Institute 1994 Feb 16; 86(4):281-86

Mandair D et al. Prostate cancer and the influence of dietary factors and supplements: a systematic review. Nutrition & Metabolism (London) 2014 Jun 16; 11:30

Sinha R et al. Meat and meat-related compounds and risk of prostate cancer in a large prospective cohort study in the United States. American Journal of Epidemiology 2009 Nov 1; 179(9): 1165-77.

Zheng W, Lee S. Well-done meat intake, heterocyclic amine exposure, and cancer risk. Nutrition and Cancer 2009; 61(4): 437-46