Tuesday, March 20, 2012

Is Meat Bad for You?

I came across a convincing critique of the recent headlines claiming that eating meat greatly increases your chance of dying. The discussion is fairly detailed; the critic pretty clearly doesn't believe that the conclusions reported can be consistent with the data, given what appear to be internal inconsistencies: A larger effect after controlling for other factors then before, despite the fact that the other factors are mostly getting worse as the amount of meat eaten increases. 

But the real killer fact is much simpler. The studies reported on covered two groups of people over a period of more than twenty years. Total mortality from all causes was less than one percent. So what is being reported as a 13% increase in mortality due to eating one more serving of meat is, assuming everything in the study is correct, a 13% increase in a mortality rate of less than one percent, or an additional mortality of about one in a thousand over twenty plus years. 

I also found another piece offering a more general criticism of results of this sort—claims about the effect of nutrition based on studies of what some large group of people ate and what happened to them. Such results are often newsworthy but, at least according to the author of that piece, always or almost always fail to be supported by followup studies.

Correction:

Looking at the reports more carefully, I think the critique is wrong in at least one important respect. The death rate is not less than 1% for the whole study period, it is less than 1% per year. The total death rate over the period appears to be about 20%, which greatly weakens the force of the argument I cited.

16 Comments:

At 8:15 PM, March 20, 2012, Blogger Joe said...

The basic problem with the study is that the groups of people who ate a lot of meat versus the groups that ate little to no meat differed in many ways: such as bmi, activity level, and other dietary differences. The authors of the study did try to account for all of these differences and control for them using statistical techniques, but such techniques are, inevitably, estimations with unknown margins of error. The question is whether the increased mortality rate associated with meat-eating is due to the meat-eating or some other confounding factor that they either didn't take into account or didn't accurately control for. Not to mention that the data in the study was self-reported, which leads to further possibilities of error.

 
At 6:42 AM, March 21, 2012, Anonymous Bill Drissel said...

> always or almost always fail to be supported by followup studies.

Evidence that we are chasing statistical "noise" in the data. Correlation without a convincing, underlying, causal theory is a good way to ask questions - a bad way to get answers.

Bill Drissel
Grand Prairie, TX

 
At 7:24 AM, March 21, 2012, Blogger August said...

This is Taubes take on the study. Robb Wolf addressed it recently too, and said what I think-
this isn't science. We've got some pretty expensive studies that need doing just to resolve the whole insulin debate that has been going on for my entire lifetime. The 'researchers' should be fired for this nonsense. Waste of money. The data isn't even accurate, much less the conclusions.

 
At 9:18 AM, March 21, 2012, Anonymous RKN said...

Funny, March must be the month for reporting on shoddy science:

http://www.rknibbe.com/Wordpress/?p=639

 
At 10:51 AM, March 21, 2012, Anonymous mobile said...

I don't know if avoiding red meat really makes you live longer, but it will make your life seem longer.

 
At 5:59 PM, March 21, 2012, Anonymous joeftansey said...

Epidemiology vs Controlled studies.

 
At 6:55 PM, March 21, 2012, Blogger Dave Lull said...

See also Denise Minger's "Will Eating Red Meat Kill You?":

http://www.marksdailyapple.com/will-eating-red-meat-kill-you/#axzz1po3rA7tk

 
At 5:50 AM, March 22, 2012, Blogger joeftansey said...

August,

Gary Taubes critiquing epidemiology is oh so rich.

I'm reading your link and I can't stop laughing.

 
At 10:34 PM, March 22, 2012, Anonymous js290 said...

http://healthcorrelator.blogspot.com/2012/03/2012-red-meat-mortality-study-arch.html

 
At 11:12 PM, March 23, 2012, Anonymous Nightrunner said...

Correlation. Causation. Toilet. Flush

 
At 8:50 AM, March 24, 2012, Blogger brauneyz said...

Didn't read the study but I'll predict that more folks choke to death on hot dogs than broccoli. Do I win?

 
At 12:44 PM, March 29, 2012, Blogger Kim Mosley said...

You probably want to fix the typo "eating eat" in the first sentence.

 
At 5:57 AM, April 04, 2012, Anonymous Anonymous said...

Does the study distinguish meat preparation? It's well-known that charred meat contains carcinogens.

 
At 9:42 AM, April 10, 2012, Anonymous econtiger said...

This is a subject near and dear to me, as I went Vegan for 1.5 years as a result of reading "The China Study" which advocates drastically reducing consumption of animal proteins to improve health.

However, for about 3 months I became a sort of nutrition science junkie, reading about a combined 500 or so books on diet/nutrition, detailed blog posts, and pubmed.com summaries.

I was finding more and more research on the benefits of omega-3 consumption, which predominately comes from fish and to a lesser degree organically grown meat and eggs. It seemed so many scientists advocated for either reducing meat / cholesterol / saturated fats, and yet others had pretty compelling evidence the other way. Half of what I read said one thing, the other half the other.

So I finally decided to investigate the raw data personally. I got a hold of the raw data that the China Study was based on and spent about 4 hours with Excel and did my own crunching. What I found strongly supporter the argument that animal products and fish were healthy rather than unhealthy. Interestly, by far the biggest mortality single-variable correlation was consumption of white rice (very good) versus consumption of wheat (extremely bad). Personally I don't believe it is issue so much of white rice being healthy, but rather of wheat consumption being extremely unhealthy (slightly worse than smoking half a pack a day in terms of all-cause mortality).

Conventional wisdom is that whole grains are good, but the research I did found this to be totally false. I cut out grains (except for occassionally cheating, I'm not perfect) and have experienced greater energy and weight loss.

For anyone interested, I highly recommend the following reviews that take the position that red meet is good for you (or at least not bad for you):


http://www.marksdailyapple.com/will-eating-red-meat-kill-you/#axzz1reersLlu


The following one is rather long and detailed; however I consider this analysis essential reading for anyone deeply interested:

http://rawfoodsos.files.wordpress.com/2010/08/minger_formal_response2.pdf

 
At 5:38 AM, June 22, 2012, Anonymous enna. LA said...

If a vegetarian or vegan ever gets self-righteous, smile real big, show your teeth, point to your canine teeth, and say, “They evolved and are used primarily for firmly holding food in order to tear it apart, and occasionally as weapons.” Humans, are the ultimate predators. We evolved to be carnivorous. We eat meat. Do you think early man would have survived without meat? They “could” have… W/E… like a caveman is going to forego hunting deer for meat in lieu of getting iron from scouring the earth for lentils and spinach. Let’s be realistic.

 
At 12:22 PM, August 13, 2012, Anonymous Joey Miller said...

To the above poster,

If a non-meat eater is acting "self-righteous", then they must be an ethical vegetarian. Your response about our evolutionary history as hunters is as inappropriate as justifying slavery by looking to the history of civilization.

 

Post a Comment

<< Home