Meat Causes Cancer, Says World Health Organization

After significant investigation of more than 40 years of research, the World Health Organization’s research team has classified meat as carcinogenic. This includes both red meat and processed meat, though processed meat was classified as a more certain risk. The research was published in the British Medical Association’s journal, Lancet.

The WHO’s International Agency for Research on Cancer (IARC) investigated volumes of research on both processed meats and red meats. The IARC announced they found the prevailing research was strong enough to classify processed meat as a Group 1 carcinogen – the most certain classification. This means that the research was strong enough to identify processed meats as “carcinogenic to humans.”

This puts processed meat in the same category given to tobacco and asbestos.

According to the WHO, this classification comes as a result of a series of studies that show that processed meats cause cancer. These studies include large-scale human population studies as well as clinical studies.

Hundreds of studies analyzed

The IRAC’s research consisted of a meta-analysis that included more than 700 human epidemiological studies that reported on red meat, and more than 400 human epidemiological studies on processed meats. Because some of these studies investigated red meat and processed meat, the total study count included in the meta-analysis was 800. According to the WHO’s press release:

“The IARC Working Group considered more than 800 studies that investigated associations of more than a dozen types of cancer with the consumption of red meat or processed meat in many countries and populations with diverse diets. The most influential evidence came from large prospective cohort studies conducted over the past 20 years.”

The meta-analysis was conducted by 22 scientists from 10 different countries. After each had performed their respective analytical calculations, they convened to come to a consensus on the research. This is the largest review of research done on meat and cancer so far.

Types of cancer clearly associated with processed meats include colorectal cancer, pancreatic cancer and pancreatic cancer. These are leading cancers throughout the world, especially among countries that consume the most meat.

The WHO reported that about on a global basis, some 34,000 cancer deaths per year worldwide are caused by processed meat diets. The estimate was calculated by a scientific research organization called the Global Burden of Disease Project.

The WHO’s calculation of the cancer risk found a relationship between processed meat and cancer:

“In those studies, the risk generally increased with the amount of meat consumed. An analysis of data from 10 studies estimated that every 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by about 18%.”

This means that for every 50 grams of processed meat eaten per day, ones cancer risk is increased by 18%. How much is 50 grams, you ask?

• two slices of ham is about 50 grams
• two slices of Canadian bacon is about 50 grams
• one hot dog is about 50 grams
• six slices of typical bacon is about 50 grams
• five slices of salami is about 50 grams

The average American at 71 pounds of beef, lamb, veal and pork in 2013. If you divide 71 by 365 days in a year, we find that the average American ate 88 grams of meat every day.

But not all that meat is processed.

About 60 percent of America’s meat consumption is red meat, and only 22 percent is considered processed. But the average consumption per person also includes those who don’t eat meat or only eat a little meat.

What meats are classified as processed?

A significant percentage of the total meat consumed in Western countries is processed. Processed meats include:

• Salami
• Corned beef
• Pepperoni
• Chicken nuggets
• Canned meats
• Sausages
• Hot Dogs
• Bologna
• Charcuterie
• Bacon
• Ham
• Beef jerky
• Meat sauces

Basically, a processed meat is any type of meat that has been:

• Cured
• Smoked
• Dried
• Salted
• Canned

Red meat classified as Group 2A carcinogen

The cancer risk doesn’t end at red meat. The IARC also classified red meat as a carcinogen – giving it the classification of a Group 2A carcinogen. This classification is described as “probably carcinogenic to humans.”

The reason for the difference in classification is the extent of the evidence. The evidence for processed meats is so strong that its classification is higher. There are very clear studies linking red meat with cancer, but just not as strong as that for processed meats.

Red meat, according to the WHO research, includes beef, veal, pork, lamb, mutton, horse, and goat.

The IRAC’s research paper estimated that another 50,000 cancer deaths worldwide are likely to be caused by eating red meat.

Processed meat and cancer

Many of the studies have referenced processed meats. For example, in 2011, Swedish researchers  found that eating red meat significantly increases a man’s risk of pancreatic cancer, and eating processed meats increases both men’s and women’s risk of contracting pancreatic cancer – considered one of the deadliest cancers.

The research, from Sweden’s National Institute of Environmental Medicine in Stockholm, analyzed eleven clinical (human) studies that followed 6,643 pancreatic cancer patients. The study found that eating more red meat increased a man’s risk of pancreatic cancer by almost 30%, but not in women.

However, both men and women have an increased risk of pancreatic cancer – by almost 20% – from eating more processed meats.

The study was published in January’s British Journal of Cancer.

Pancreatic cancer has one of the worst survival rates of any other cancer. Pancreatic cancer survival rates are about 25% for one year, and 6% for five years. In the U.S. 38,000 people were diagnosed with pancreatic cancer in 2011, and about 34,000 died of pancreatic cancer. It is the fourth highest cause of cancer deaths.

The study gauged red meat consumption by categorizing those who ate 120 grams more red meat a day for the red meat analysis, and those who ate 50 grams more processed meat for the processed meat analysis.

This is not the first study that has associated eating red meat and processed meats with cancer. Multiple studies have found that colorectal cancer, stomach cancer, liver cancer, throat cancer, lung cancer and other forms of cancer have also been associated with eating red and processed meats.

Why meats are so dangerous

When meats are cooked, they become high in a number of compounds. Let’s discuss a few:

Heterocyclic amines (HCA). HCAs are produced when meat is cooked at high temperatures. This includes frying, grilling and roasting. HCAs have been linked to cancer in a number of studies.

Polycyclic aromatic hydrocarbons (PAH). PAHs are also produced by cooking meats at high temperatures – again, frying, grilling and roasting.

Nitrites and nitrates. These are salts that are added to meat to preserve them. Nitrates have been shown to cause DNA damage.

Heme iron. This compound is found in red meat. These catalyze to form N-nitroso compounds, which have been suspected as cancer-causing.

The intestinal bacteria link

To this, we can add significant research illustrating that red meat stimulates the growth of certain pathogenic bacteria colonies. These bacteria have been shown in other research to produce enzymes that have been linked with colon cancer and other cancers.

These pathogenic bacteria also produce an array of other byproducts, sometimes referred to as endotoxins. One type of these endotoxins – linked with cancer and an array of other conditions – are called lipopolysaccharides. We’ve also discussed some of the other conditions caused by lipopolysaccharides.

Dr. Christopher Wild, the director at the IARC, commented about the WHO research:

“These findings further support current public health recommendations to limit intake of meat.”

A review of the WHO research by the American Cancer Society states:

“The American Cancer Society has long recommended a diet that limits processed meat and red meat, and that is high in vegetables, fruits, and whole grains.”

REFERENCES:

Bouvard V, Loomis D, Guyton KZ, Grosse Y, Ghissassi FE, Benbrahim-Tallaa L, Guha N, Mattock H, Straif K; International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of consumption of red and processed meat. Lancet Oncol. 2015 Dec;16(16):1599-600. doi: 10.1016/S1470-2045(15)00444-1.

Simon S. World Health Organization Says Processed Meat Causes Cancer. 10/26/15. Accessed Jan 24, 2016.

International Agency for Research on Cancer. IARC Monographs evaluate consumption of red meat and processed meat. 26 Oct. 2015.

World Health Organization. Q&A on the carcinogenicity of the consumption of red meat and processed meat. http://www.who.int/features/qa/cancer-red-meat/en/

Cogliano VJ, Baan R, Straif K, Grosse Y, Lauby-Secretan B, El Ghissassi F, Bouvard V, Benbrahim-Tallaa L, Guha N, Freeman C, Galichet L, Wild CP. Preventable exposures associated with human cancers. J Natl Cancer Inst. 2011 Dec 21;103(24):1827-39. doi: 10.1093/jnci/djr483.

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