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Is meat going to give you cancer? The answer is a very dubious maybe. Aaron helps you understand the meat announcement from the WHO, and it turns out, you might not need to panic.

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Meat causes cancer!! You're all freaking out! Are you all going to die? Someday, unfortunately, yes, but not likely for a long time. And almost certainly not because you ate some bacon. This is Healthcare Triage News...


News coverage of the WHO, International Agency of Research into Cancer or IARC's new announcement about meat and cancer RUINED MY MONDAY. Headline after headline about how meat causes cancer - you all lost your minds. Of course, the IARC wasn't nearly as inflammatory as the news made them out to be. Yes, they said processed meat should be classified as "carcinogenic to humans". They also said red meat in general is "probably carcinogenic to humans". This puts red meat into the same category as tobacco smoke and alcohol, and it shouldn't be surprising to you that those aren't at all the same. Smoking, terrible! Alcohol, debatable. But the IARC classification cares only about the hazard and not about the magnitude.

Confused? I love this gem from David Phillips, a cancer researcher in the United Kingdom:
"To take an analogy, think of banana skins. They definitely can cause accidents - 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." (David Phillips)
When you tell people that eating 50 grams of processed meat a day increases their risk of cancer by 18%, I hope that all of us Healthcare Triage viewers immediately recognize that that a relative-risk increase, not an absolute one, and that's what we should care about.

As blogger "Kevin Drum calculated, this means that if you eat a few ounces of processed meat every day for the rest of your life, your lifetime risk of getting colorectal cancer goes from 4.5% to 5.3%." 

And even at that I'll give a maybe. Last March, I reviewed the evidence against red meat at the upshot. You read my New York Times columns, right? No new data have appeared. The WHO and I looked at the same stuff; we came to different conclusions.


Let's start with some data. Here in America, we've been reducing our meat consumption for the last decade or so. This hasn't resulted in a massive decrease in obesity rates or deaths from cardiovascular disease. The same reports also show that we eat significantly more fruits and vegetables today than we did decades ago. We also eat more grains and sweeteners.

Lots of people point to studies, like a big one from last year, that found that increased protein intake is associated with large increases in mortality rates from all diseases, with high increases in the chance of death from cancer or diabetes. A closer examination of the study, though, tells a slightly different story.

It was a cohort study of people followed through NHANES. Overall, the analysis in question found that there were no association between protein consumption and death from all causes, or cardiovascular diseases, or cancer individually when all participants over age 50 were considered. They did detect a statistically significant association between the consumption of protein and diabetes mortality, but they cautioned that the number of people in that analysis were so small that any result should be taken with caution.  The scary finding I mentioned earlier that some people point to is from a sub-analysis that looked only at people aged 50-65. But when you look at people aged 65 and older, the opposite was true. High protein was associated with lower levels of all-cause and cancer-specific mortality. If you truly believe that this study proves what people say, then we should advise people over the age of 65 to eat more meat - no one does. If I want to cherry-pick, I might point you to a 2013 study that used the same NHANES data to conclude that meat consumption is not associated with mortality at all. 

Let's avoid cherry-picking though. A 2014 meta-analysis examined all of the prospective studies and found that people in the highest consumption group of all red meat had a 29% relative increase in all-cause mortality compared to those in the low-consumption group. But most of this was driven by processed red meats, because not all red meats are the same. Of course, a previous 2010 meta-analysis and systematic review found that overall red meat consumption wasn't associated with higher mortality rates. So even this is disputed.

Epidemiologic evidence can only take us so far though. We really do need randomized-control trials to answer these questions. They do exist with respect to effect on lipid levels. A meta-analysis examining eight of them found that beef versus poultry-and-fish consumption, didn't change cholesterol or triglyceride levels significantly. All of this misses the bigger point though - it's important to understand what "too much" really is. People in the highest consumption groups of red meat in all of these studies had one to two-or-more servings a day. The people in the lowest serving groups had about two servings per week. So if you're eating multiple servings of red meat a day, then yes, you might want to cut back a little bit. I'd wager that most people watching this video aren't eating that much though. If you eat a couple of servings a week, you're likely just fine.

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