by Dr. Dan Shuman DC, CCSP
If you’re reading this then you’ve probably read or at least heard of the recent report from the International Agency for Research on Cancer (IARC) which is a part of the World Health Organization (WHO). The WHO report classifies cured and processed meats as carcinogens and put them in the same category as other cancer causing agents like asbestos, alcohol and arsenic; and those are just the As! Of course, this isn’t a new argument or even the first time meat has been scrutinized. The past 40 years are littered with attacks on red and processed meat because of cholesterol, a compound called TMAO and various other reasons. But what does the scientific research really say about red meat and how should the average reader interpret sensational media headlines?
The Processed Meat Study
The study that was released is a meta-analysis, a study evaluating over 800 studies. Twenty-two experts from 10 countries conducted the work and then voted on the results, so we can’t just scoff at the results. The main conclusion was that processed meat was classified as carcinogenic to humans (Group 1), based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer (CRC). In other words, there is convincing evidence that processed meat causes cancer based on epidemiological studies.
A few key words found there are “based on epidemiological studies”. Most epidemiological studies are observational, as opposed to experimental. Observational studies are a good place to start in scientific research because they can help generate a hypothesis that can then be tested further. They can help us find correlations between different variables but it is important to note that they do not provide proof or causation. Correlation is not the same thing as causation. Only experiments, with controls and manipulated variables like those found in a RTC, can confirm proof that one variable caused another variable to happen, like processed meat causing cancer. This study does not and should not be interpreted to that the relationship between processed meat and cancer is causative.
With that said, we cannot completely disregard their findings. With even just a cursory look at the clinical research, there are a number of studies that have consistently identified a positive correlation with processed meat and cancer at specific sites in the body. These sites include the colon and the rectum primarily. Lifetime risk of developing of CRC is approximately 4.5 percent%. The researchers in WHO report were able to conclude that a 50-gram portion (roughly 6 slices of bacon, a hot dog or 2 slices of ham) of processed meat eaten daily increases the risk of CRC by 18%, which elevates total lifetime risk to just under 5.5%. In comparison, smoking increases one’s risk of getting lung cancer by 2,500%. A few other substances, other than those mentioned above identified by the IARC as “Group 1” agents include: estrogen and progesterone contraceptives, alcohol, outdoor air pollution, UV radiation, tobacco and a popular breast cancer chemotherapy drug, Tamoxifen. Interesting that a medicine that is on the World Health Organization’s ‘List of Essential Medicines’ is also listed as a causative agent of cancer!
Red Meat – To Eat or Not to Eat.
The study also placed fresh red meat in the “group 2A” category, which suggests that it is “probably carcinogenic” to humans based on limited evidence. Limited evidence means that a positive correlation has been observed between fresh red meat and cancer but that other explanations for the observations (simple chance or bias) could not be ruled out. Like I mentioned, red meat has been vilified in the media for over 40 years; however there is conflicting evidence when it comes to fresh red meat and cancer. For one, a large majority of the data comes from studies that require patients to recall what they ate. These are called food frequency questionnaires (FFQ) and they are riddled with problems. Humans aren’t great at recalling what they ate for dinner the prior night, much less how much meat they consumed for a whole year. Validation studies performed on the FFQ continually show that people tend to report what they think they should be eating instead of what actually goes into their mouth. Also, people with “diagnosed medical condition”—including high cholesterol, high triglycerides, diabetes, high blood pressure, stroke, cancer, and heart disease—were much more likely to mis-report their meat consumption than folks without a diagnosed medical condition. Stay with me folks because there is one more point I’d like to make here. The people in these observational studies that ate more red meat were also found to have higher rates of smoking and drinking; eating fewer fresh fruits and vegetables; exercising less and engaging in other unhealthy behaviors! So yeah, it’s just the meat that’s causing the cancer, right?!
High quality pastured or grass-fed red meat after all is a very nutrient dense substance. It has a higher concentration of omega-3 fatty acids that commercial beef. It’s loaded with absorbable vitamins and minerals like iron and zinc and conjugated linoleic acid, which may be anti-carcinogenic. It is a complete source of protein and is easy for the body to break down compared to other sources.
What Impact Will This Have?
So what does this whole thing mean? My opinion is that we probably shouldn’t be eating a lot of commercially processed meat like bologna, hot dogs and bacon. These products contain harmful ingredients like nitrites and preservatives, which aren’t essential for optimizing health. We should instead be focusing on maximizing nutrient density through abundant consumption of vegetables primarily along with fish, high quality red meat, fruits, fats, nuts and seeds and staying away from processed industrial oils, sugar and grains. We should probably stick to gentle methods of cooking our meat as pan searing and grilling create nasty little carcinogenic compounds called heterocyclic amines (HCA) among others. Interesting to note, grilled white meat like chicken can contain nearly 200 times as much HCAs as a steak, at least in the well-done portion of the meat. We should also focus our attention on getting appropriate amounts of movement (not just exercise), sleep and reduction in stress. Speaking of stress reduction, hopefully this article will help ease some of the tension out there caused by the recent WHO report.
Dr. Dan Shuman is a Georgia native, a Summa Cum Laude graduate of LaGrange College and a Magna Cum Laude graduate of Life University. He is a nationally certified instructor in Active Release Techniques and CrossFit enthusiast. Call 404-377-0011 to schedule an appointment.