Eating Red Meat Twice Weekly May Up Cancer Risk Nearly 20%

Days after the World Health Organization classified red meat as a probable human carcinogen, new research has strengthened the link between red meat consumption and cancer. (Photo: Getty Images)

A University of Oxford study discovered that participants who ate four servings of red meat a week were 42 percent more likely to develop colorectal cancer than those who had one serving or none at all. Participants who ate red meat at least twice a week were 18 percent more likely to develop colorectal cancer than vegetarians.

The study, which will be presented Tuesday at a conference for the National Cancer Research Institute, tracked the meat-eating habits of more than 500,000 British men and women aged 40 to 69. (Researchers didn’t quantify the amount of each serving — they only tracked how often people ate meat.)

Surprisingly, the research did not find a link between eating processed meats and an increased risk of colorectal cancer, though the World Health Organization (WHO) identified processed meats as a “known human carcinogen” last week, citing one of the top reasons as its link to colorectal cancer. The WHO experts concluded that each 50-gram portion of processed meat (less than 2 ounces) eaten daily increases the risk of colorectal cancer by 18 percent.

According to the American Cancer Society, colorectal cancer is the third most common cancer diagnosed in men and women in the U.S. More than 93,000 Americans will be diagnosed with colon cancer in 2015 and nearly 40,000 will be diagnosed with rectal cancer, the organization says.

Lead study author Kathryn Bradbury, PhD, a nutritional epidemiologist at the University of Oxford, tells Yahoo Health that there may be a few compounds in red meat that explain the link with bowel cancer.

“Cooking meat produces heterocyclic aromatic amines (HAA), which are suspected carcinogens,” she says. “Red meat also contains haem iron and, when eaten, this leads to the formation of N-nitroso-compounds (NOC), which again are suspected to be carcinogenic.”

The message is simple, Bradbury says: If you’re big on eating red meat, it’s a good idea to cut back.

Bradbury’s findings come at an interesting time for meat consumption.

The International Agency for Research on Cancer (IARC), a research division of the World Health Organization, announced last week that processed meats such as bacon, sausage, ham, and hot dogs cause cancer.

Related: You’ll Be Surprised What Counts as Processed (and Red) Meat

The organization also identified red meat as “probably carcinogenic,” meaning it’s likely to cause cancer as well.

Processed meats were classified as a Group 1 carcinogen to humans, in the same group as smoking tobacco and asbestos exposure. Substances in this group have “sufficient evidence” of carcinogenicity in humans, according to the IARC.

The IARC defines processed meats as “meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation.” Most processed meats contain pork or beef, it adds, but may also contain other red meats, poultry, offal (organs and entrails of an animal), or meat by-products.

Popular processed meats include sausage, jerky, bacon, hot dogs, and kebabs, along with everyday lunchmeat such as ham, salami, corned beef, pastrami, and bologna, as well as canned meats and packaged meat-based sauces.

Red meats include beef, veal, pork, lamb, mutton, horse, and goat.

The organization said that the individual risk of developing colorectal cancer from eating processed meats is “small” but increases with the amount of meat a person eats.

Related: The Science Behind Why We’re So Obsessed With Bacon

The panel also determined that eating 100 grams of red meat per day (about 4 ounces) may raise a person’s risk of colorectal cancer by 17 percent.

“This association was observed mainly for colorectal cancer, but associations were also seen for pancreatic cancer and prostate cancer,” the organization said.

The WHO declaration is one of the most aggressive stances taken by an international health organization and is, thereby, highly controversial — even within WHO itself. According to the Washington Post, the panel decision was not unanimous and is expected to face criticism within the United States, where processed and red meat still forms the base of most meals and is backed by a powerful lobbying industry.

Other organizations have encouraged people to eat less meat for better health but have stopped short of declaring that meat consumption causes cancer.

The American Cancer Society recommends limited red meats and processed meats. “Because of a wealth of studies linking colon cancer to diets high in red meats (beef, lamb, or liver) and processed meats (hot dogs, bologna, etc.), the Society encourages people to eat more vegetables and fish and less red and processed meats,” the ACS says on its website.

A study by the National Cancer Institute of 500,000 people found that those who ate red meat daily were 30 percent more likely to die during a 10-year period than those who ate very little red meat. Eating processed meats also increased the risk of death.

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