Red meat is back in the news. This happens pretty regularly and it’s never good news. Some new study gets publish, the media goes crazy and everyone panics. I often find myself panicking about things I hear or read but in this case I actually didn’t think twice about it. When this new report about cancer and meat came out last week from the International Agency of Cancer Research (IACR) I didn’t panic and swear off bacon, steak and hamburger. As I mentioned above, this isn’t new news. I’ve read critiques of similar studies in the past and feel comfortable with my understanding of the subject.
A conversation with a friend prompted me to write this post. She wanted to know what I thought of the study. I told her I wasn’t really worried. She seemed surprised. We chatted a little and I told her I’d send her some information that might make her feel a little better about the whole thing. As I was driving away it occurred to me that most people don’t spend their day reading about nutrition and probably don’t have the time or interest to read scientific studies. So, nerd alert, I do these things. You probably know that but it seems funny to actually admit it. My husband is always making fun of the stuff I read. Anyway, back to my point about this post. I thought that perhaps she wasn’t the only one that might like a different perspective on the most recent study about cancer and red meat.
Here’s what I hope to cover in this post:
- What an epidemiological study is
- What the draw backs of an epidemiological study are
- Review an article by Cancer Research UK
- Review information from Chris Kresser on red meat and cancer studies
- Give you my perspective on toxic load
The study being discussed here is the latest report from the International Agency of Cancer Research (IACR) that came out last week, October 2015. 22 scientists from ten countries got together and evaluated 800 epidemiological studies. The 800 studies, studied investigated the association of cancer with the consumption of red meat or processed meat. Many countries, several continents and diverse ethnicities and diets were part of these studies. (1)
Epidemiological Study
So, 800 epidemiological studies were evaluated. Epidemiological study? I didn’t know what that was until I started studying nutrition. Here’s a quote from Chris Masterjohn about epidemiological studies. This quote is actually taken from an article he wrote back in March 2009 in response to another study about eating meat and dying. (2)
Here’s what he says about epidemiological studies (bold emphasis is mine):
Epidemiological studies such as this one are observational in nature. Observation is the first step of the scientific method. One then develops a hypothesis to explain those observations, and then tests the hypothesis through experimentation. Epidemiological studies, therefore, are useful for generating hypotheses, but not for testing them.
If you have time you should give that article a read.
Chris Kresser also makes the point that observational studies do NOT prove causality. They demonstrate associations or relationships between different variables that are sometimes causal and sometimes not. They are useful for generating hypotheses and identify trends they do not prove anything. An additional limitation of observational studies is their inability to detect the effects of important differences between individual study participants. More on that later. (4)
O.k., that’s what an epidemiological study is, a gathering of information and a starting place for more studies. Cause and effect does not come from an observational study. A relationship may be noticed but to prove cause and effect more tests must be done.
Study Review
The information presented by the IACR last week actually vilified processed meat not red meat. Processed meat was classified as a ‘definite’ cause of cancer, bowel cancer actually. Red meat classified as only a ‘probable’ cause of cancer. Either way, not good and probably makes you feel uncomfortable about even considering the idea of eating a hamburger or steak. Sadly, this isn’t really new news. The question is what does it really mean and more importantly what does it mean to you. How much meat does it take to cause cancer? How many cases of cancer can we expect from meat consumption? Here’s a quick quote from Cancer Research UK (3):
…a prolonged high-meat diet isn’t terribly good for you. But a steak, bacon sandwich or sausage bap a few times a week probably isn’t much to worry about. And overall the risks are much lower than for other things linked to cancer – such as smoking.
It’s a UK article, I don’t know what a ‘bap’ is.
Here are the categories that meats fall into:
- Red Meat: beef, lamb and pork
- Processed Meat: bacon, sausage, hot dogs, ham, salami and pepperoni – meat that has been cured, salted, smoked, or preserved
- White Meat: fresh chicken, turkey or fish (don’t appear to increase risk of cancer)
Here’s another quote from Cancer Research UK about the quality of meat because I’m sure you’re all thinking – but I eat grass-fed meat from my neighbor’s farm that’s butchered locally (I know I was). Evidently that doesn’t matter, bummer.
…it isn’t about the quality of the meat, or whether it’s from the local butcher or your supermarket. The evidence so far suggests that it’s probably the processing of the meat, or chemicals naturally present within it, that increases cancer risk.
I have a feeling I’m not making you feel better. I will, I think but it might seem like I’m throwing more bad news at you before I get to the stuff that I think puts things in perspective. Stay with me.
So, the IARC assigns things to Cancer groups. Group 1 being the worst and classified as causing cancer, then there is group 2A – probably causes cancer, group 2B – possibly causes cancer, group 3 not classifiable as a cause of cancer and finally group 4 probably not a cause of cancer. Processed meats have been assigned to group 1 and red meat has been assigned to group 2. Here’s an info-graphic that outlines the groups.
I bet you’re wondering what else has been classified as group 1. Well our processed meats are now in the good company of asbestos, arsenic, tobacco and alcohol. Yup, nice company.
What about red meat you ask? Well another fine member of group 2, a probable cause of cancer, shift work. Time to change jobs.
Here’s the rub and I hope the start of information that makes all of this less scary.
These groupings are all about the probability of causing cancer, NOT how much cancer they cause. I know, WHAT? Well, this is the good part. Basically, the IARC gives information on whether or not something causes cancer, not how potent something is at causing cancer. I like this analogy from the Cancer Research UK page:
To take an analogy, think of banana skins. They definitely can cause accidents, explains Phillips, but in practice this doesn’t happen very often (unless you work in a banana factory). And the sort of harm you can come to from slipping on a banana skin isn’t generally as severe as, say, being in a car accident.
But under a hazard identification system like IARC’s, ‘banana skins’ and ‘cars’ would come under the same category – they both definitely do cause accidents.
Interesting and thought-provoking dontcha’ think? Here’s another info-graphic about tobacco and meat (think bananas and cars).
The end of the article at Cancer Research UK says the Government advises that people cut back on red and processed meat consumption. Less is better. They don’t say remove it entirely from your life. You can if you want to. I’m not going to.
This has turned into a long post. I’ll try to wrap things up with some insights from Chris Kresser’s article Red Meat & Cancer – Again! Will It Ever Stop? If you’re still feeling uneasy you might want to take a few minutes and red the whole Kresser article. He quotes then translates information from some previous studies regarding red meat and cancer. Over all he doesn’t feel that the evidence from past scientific studies is as strong as proponents suggest.
Here’s a quote:
the association between red meat and cancer is not strong (i.e. comparing bacon to cigarettes is absurd), and in fact is often not distinguishable from chance. If red meat really did cause cancer, you’d expect to see a linear (continuous) increase in cancer rates as red meat consumption increased. But that’s not what we see in many cases. In fact, in some studies you actually see a decrease in cancer rates in the people who ate the most red meat.
Isolating Variables
He also highlights a part of a study that says the ability to analytically isolate the independent effects of red meat consumption from other dietary and behavioral factors is limited. In other words, people that do things perceived as healthy do lots of other things perceived as health and people that do things perceived as unhealthy tend to do lots of other things perceived as unhealthy and it’s hard to separate or isolate each “thing” to determine which variables are related. Eating red meat is perceived as unhealthy but in observational studies the people that eat the greatest amounts of red meat also tend to smoke, drink more, eat less healthy fruits and vegetables and even exercise less. Chris Kresser says this isn’t speculation, numerous studies show this. You can read his references on this here.
…most Americans that eat red meat eat it with a huge bun made of white flour, with a serving or more of other refined carbohydrates (chips, fries, soda) cooked in rancid, industrially processed vegetable or seed oils. How do we know that it’s the red meat – and not these other foods – that is causing the increase in cancer?
Study Participants
Now, finally, what I think is the most important point, differences between study participants. As mentioned above, it’s difficult for observational studies to detect the effects of important differences between study participants. For example, those of you that read my blog are interested in health and nutrition. You may have even transitioned away from the standard American diet to a more whole food, paleo type diet. Perhaps you’ve suffered from some GI dysfunction but have found your way to a healthy gut. These positive lifestyle changes have increased your energy so now you exercise more. People like you don’t make up the majority of participants in an observational study because people like you aren’t the majority. Chris Kresser states that 95% of typical study participant eat a standard American diet, don’t exercise and more than likely suffers from, at the very lease, gut dysbiosis. The healthy 5% in the study are included in the overall results even though it’s unlikely that the consumption of red meat would have the same impact on their health as it would on the typical participant. Here’s another quote from Chris Kresser that I think sums it up.
…given what we already know about the influence of diet, lifestyle, and the microbiome on cancer risk, that someone following a Paleo-type diet and lifestyle will not share the same cancer risk as someone following a Standard American Diet and lifestyle, even if they are eating an equivalent amount of red meat.
Toxic Load
For me, the easy way to sum all of this up is Toxic Load. Everyone’s toxic load is different due to our individual toxic exposures. Do you eat organic food? If so you’ve reduced the amount of pesticides your body has to deal with. That has reduced your overall toxic load. Do you exercise, include fiber in your diet, keep your vitamins and minerals at healthy levels, drink lots of water, eat lots of colorful vegetables, avoid chemical cleaners and toxic skin care products? If so then you’ve reduced your toxic load even more. How’s your detoxification system? Do you do an annual liver cleanse? These are some of the things you can do to keep your body functioning optimally. Ideally, reducing your toxic load improves body function and reduces the potential for degenerative disease.
If you strive to live a healthy life that includes whole, organic foods, healthy fats, limited sugars, lots of vegetables and exercise you probably don’t have to worry about including some bacon, hamburger, grass-fed beef or other meats in your diet. I’m not going to. If by chance you fit the profile of the 95% this might be an opportunity to start thinking about making some lifestyle changes. Wouldn’t it be exciting if the percentages were reversed and the 95% was the healthy group? Someday.
Eat Well, Feel Good, Have Fun!
References:
- www.thelancet.com/journals/lanonc/article/PIIS1470-2045(15)00444-1/fulltext
- http://blog.cholesterol-and-health.com/2009/03/will-eating-meat-make-us-die-younger.html
- http://scienceblog.cancerresearchuk.org/2015/10/26/processed-meat-and-cancer-what-you-need-to-know/
- http://chriskresser.com/red-meat-cancer-again-will-it-ever-stop/
I’m Amy a board certified holistic nutritionist, certified functional nutritionist and lifestyle practitioner and certified Life Coach. I help women in midlife understand the changing needs of their body so that they can stop dieting and lose weight permanently. At 56 I live what I teach. Don’t believe the story that your best years are behind you. They are not. Your best years are just starting!