Red meat; it contains numerous vitamins and minerals essential for a well-balanced diet. But with new studies linking it to cancer and other diseases, it would appear as though red meat’s good reputation is now being put into question.
Defined as any meat that comes from mammalian muscle, red meat includes anything from beef, lamb, pork, goat, veal, and mutton. Although it has long been a food staple, Americans are significantly reducing their intake, having consumed approximately 106.6 pounds of red meat in 2016. This might seem a considerable amount, but in comparison to 1970 where an average of 145.8 pounds of red meat was consumed per capita, this is a significant reduction. In fact, in the last 10 years consumption of red meat has fallen by around 10 pounds per person, with 2014 seeing the lowest intake of red meat since 1960, at just 101.7 pounds per person being eaten.
In this day and age where concerns about where our food comes from, what we are putting into our bodies, as well as animal welfare causes reign supreme, millions of Americans are opting for plant-based foods over meat-based products. This is due to many believing them to be healthier alternatives, and with approximately 8 million adults in the US (according to a 2016 Harris Poll) identifying as either vegetarian or vegan, it is clear that there is a shift towards healthier eating. The 2016 Harris Poll also found that 37 percent of adults “always” or “sometimes” eat vegetarian meals when eating out, with 36 percent of these citing health reasons for their choice.
A position paper from the Academy of Nutrition and Dietetics claimed that a plant-based diet can lower the risk of type 2 diabetes by 62 percent, as well as reduce the risk of heart attack and stroke. However, it is not only the health benefits that come with plant-based diets that are driving us away from red meat, but rather the health risks that have the potential to arise from eating red meat. Cancer, being the most well-established health concern around eating red meat, has been reported on by the World Health Organization (WHO) in October 2015 as being “probably carcinogenic to humans,” which means that there is some evidence that it can increase the risk of cancer.
In addition to this, the WHO came to the conclusion that processed meats, defined here as “meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation” was again, “carcinogenic to humans.” This means that there is sufficient evidence to back up the claim that eating processed meat can increase the risk of cancer. To come to these conclusions, the WHO’s International Agency for Research on Cancer (IARC) Working Group reviewed more than 800 studies assessing the effects of red and processed meats on various types of cancer. Their findings were that each 50-gram portion of processed meat (which mainly includes pork or beef) eaten daily increased the risk of colorectal cancer by 18 percent.
The IARC found evidence also of a link between red meat intake and increased risk of colorectal, pancreatic, and prostate cancers. It is suspected that cooking red meats at high temperatures, such as on the barbeque, frying, and so on is what contributes to an increased cancer risk. The National Cancer Institute (a part of the National Institutes of Health) supports these findings by stating that cooking meats at high temperatures can lead to the production of heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs); chemicals that have been shown to increase cancer risks in animal models.
It should be noted, however, that the report from the WHO concluded that the role of HCAs and PAHs in human cancer risk is not fully understood, and therefore there was not enough data to determine whether the way meat is cooked does indeed influence the risk of cancer.
Studies are also suggesting that kidney failure may be connected to the consumption of red meat, according to one performed in July 2016. Published in the Journal of the American Society of Nephrology, the study reported a dose-dependent link between red meat consumption and risk of kidney failure. In this case, participants who who were in the highest 25 percent of red meat intake had a 40 percent increased risk of kidney failure compared to those in the lowest 25 percent.
Heart disease is still the number one killer in the U.S, claiming 610,000 lives in the country every year. A number of studies have implied that red meat is potentially at fault for raising the risk of heart disease and other cardiovascular conditions. A 2014 study in Sweden of more than 37,000 men, for example, found that those who consumed more than 75 grams of processed red meat per day were at 1.28 times greater risk of heart failure than those who consumed under 25 grams daily. Another study published in 2013, found a link between red meat intake and increased risk of heart disease, but this link was not attributed to the high saturated fat and cholesterol content of red meat. Researchers from Columbia University in New York found that gut bacteria digest a compound in red meat called L-carnitine, converting it into a compound Trimethylamine-N-oxide (TMAO). Researchers found that in mice, TMAO led to the development of atherosclerosis – a condition that is characterized by the buildup of fatty substances in the arteries, which can lead to heart attack and stroke.
Similarly, diverticulitis (a condition where inflammation occurs in one or more of the sacs that line the wall of the colon) is also speculated to be caused by the intake of red meat. Compared with men who reported eating low quantities of red meat, those who reported eating the highest quantities were found to have a 58 percent greater risk of developing diverticulitis. The risk was strongest with a high intake of unprocessed red meat, the researchers found.
However, despite many studies linking red meat intake to poor heart health, other research challenges this association. A study by researchers from Purdue University in West Lafayette, IN, found that eating 3 ounces of red meat three times weekly did not lead to an increase in risk factors for cardiovascular disease. Not only this, but red meat is full of nutrients such as vitamin B-3, and has 32 percent of the recommended daily allowance of zinc. It is also high in heme-iron (which is absorbed better than plant-derived iron), vitamin B-6, selenium, and other vitamins and minerals.
All in all, public health guidelines do advise on limiting red meat consumption. The American Institute for Cancer Research, for example, recommends eating no more than 18 ounces of cooked red meats each week to reduce cancer risk, while processed meats should be avoided completely. However, there is no daily limit specified on how much or how little red meat one should consume, but rather to be aware that red meat does have nutritional value, and this should be considered in future research “in order to balance the risks and benefits of eating red meat and processed meat and to provide the best possible dietary recommendations.”