Beef may well be one of the most vilified foods on the planet today. A recent example, found on the Medical Daily website, lists seven reasons a person should avoid eating beef. Those include mentions of studies tying consumption of beef to Alzheimer's, cardiovascular disease, colon cancer and type 2 diabetes. Mad Cow Disease is reason No. 5 to never eat beef; and the fact that "cows are nice" is reason No. 7.
Downplaying this type of article as internet fear-mongering risks underestimating its impact. Consider that 72% of adults in the U.S. go online for health information, according to a Pew Research Center survey. The vast majority use search engines like Google, Bing or Yahoo to find answers to medical questions.
Beth Kitchin, assistant professor in nutrition sciences at the University of Alabama, Birmingham, said she's not surprised to find people are often confused by reports singling out this or that food as a cause of cancer.
"I think basically our whole profession is so crazy now. You can find somebody to tell you whatever you want to hear, whether it's that Paleo is great, or you need to go gluten-free, or that sugar is toxic. We are throwing out whole categories of food," she said.
"Looking at beef, reports that came out where the World Health Organization [WHO] said red meat is a carcinogen were really exaggerated. There is no food that is toxic for people. Sugar is not toxic. Beef is not toxic. That doesn't mean we shouldn't limit ourselves, but this all gets very hyperbolic. The key to good health, as boring as it sounds, is moderation."
FACT OR FICTION?
Those reports, released last October by the WHO, classified processed meat as "carcinogenic to humans" and red meat as "probably carcinogenic to humans."
According to the WHO's International Agency for Research on Cancer (IARC), a thorough review of accumulated scientific literature and a working group of 22 experts from 10 countries made the evaluations. The IARC reported that each 50-gram portion of processed meat eaten daily increases risk of colorectal cancer by 18%. The agency attributed 34,000 cancer deaths each year, worldwide, to eating diets high in processed meat. Processed meat is anything "transformed through salting, curing, fermentation, smoking or other processes to enhance flavor or improve preservation."
No specific portions or risk percentages were given for red meat, despite which the IARC still noted a connection between its consumption and cancer. The agency said this classification was based on "limited evidence from epidemiological studies showing positive associations between eating red meat and developing colorectal cancer," adding that other explanations for the observations could not be ruled out.
The IARC also noted evidence of links to pancreatic cancer and prostate cancer from eating red meat but did not elaborate. The number of cancer deaths each year the IARC said would be tied to eating a diet high in red meat could be 50,000 based on the Global Burden of Disease project, "if the reported associations were proven to be causal." Strong words, and statistics, for "limited evidence." Red meat, according to the agency, includes beef, veal, pork, lamb, mutton, horse and goat.
The day after the IARC released its report, the National Cattlemen's Beef Promotion and Research Board, financed by the Beef Checkoff, countered with comments from Beef Checkoff nutrition scientist and registered dietitian Shalene McNeill.
McNeill observed the IARC process, which lasted seven days in Lyon, France. At the end of that deliberation, the group's 22 experts in the field of cancer research had not been able to reach a majority agreement -- something they typically achieve and pride themselves on, she said.
"Billions of dollars have been spent on studies all over the world, and no single food has ever been proven to cause or cure cancer," McNeill said. "The opinion by the IARC committee to list red meat as a probable carcinogen does not change that fact. The available scientific evidence simply does not support a causal relationship between red or processed meat, and any type of cancer."
An epidemiologist, conducting research on behalf of the Beef Checkoff, Dominik Alexander, reported in the "Journal of the American College of Nutrition" that red meat did not appear to be an independent predictor of colorectal cancer.
He said: "There are a constellation of factors that are associated with the probability of getting cancer, which include age, genetics, socioeconomic characteristics, obesity, lack of physical activity, where you grew up, alcohol consumption, smoking and even your profession. The bottom line is the epidemiologic science on red meat consumption and cancer is best described as weak associations and an evidence base that has weakened over time. And most importantly, because red meat is consumed in the context of hundreds of other foods and is correlated with other behavioral factors, it is not valid to conclude red meat is an independent cause of cancer."
Other research, not associated with the Beef Checkoff, has also tended to disagree with the IARC evaluation. A recent study out of Harvard using The Nurses' Health Study and The Health Professionals Follow-Up Study found unprocessed meat intake had an inverse association with distal colon cancer and a weak, "statistically non-significant" positive association with risk of proximal colon cancer. The Women's Health Initiative and the Polyp Prevention Trial both found a 20% reduction in red meat consumption did not reduce risk of colorectal cancer.
CALL FOR MODERATION
UAB's Kitchin said she considers herself an evidenced-based person, and she sees very few trials that are thorough enough or random enough to base sweeping proclamations on.
"I'm not saying that studies showing negative outcomes are necessarily wrong, but they are often exaggerated. If you eat 10 ounces of red meat every day, that may well be bad for you. A healthy diet is all about dose and moderation."
When it comes to red meat, there is also the issue of how it is cooked, as well as what cuts a person chooses to eat. Kitchin said obviously ground beef is very different from sirloin or a filet in terms of fat and calories. In addition, some cooking methods have been shown to create substances that are carcinogenic.
"What happens when we cook at really high temperatures and that yummy stuff forms on the outside of the meat ... there is good evidence that some of those substances can be carcinogenic," Kitchin said. "Does that cause cancer in a human? How much would you have to eat? That is a leap. So if we have a grilled burger five or six times over the summer, is that dangerous? We can't say that. I'm really against demonizing any food. It's all about how often you eat things and moderation. That is the key to good health."
For More Information:
World Health Organization IARC: www.iarc.fr/en/media-centre/iarcnews/pdf/Monographs-Q&A_Vol114.pdf
Beef Board: www.beefboard.org
University of Alabama Department of Nutrition: www.uab.edu/shp/nutrition
Beth Kitchin's Blog: uabnutritiontrends.blogspot.com
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