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Recent Longitudinal Study: Red Meat and Higher Mortality

by (100)
Updated about 11 hours ago
Created March 13, 2012 at 12:27 AM

First let me apologize if this story has all ready been covered today, and for my awkward question formatting. I've been a lurker for a few months here, but this is my first post.

This recently published longitudinal study by Frank Hu of the Harvard School of Public Health was caught by NPR and is making it's daily rounds.

Article http://archinte.ama-assn.org/cgi/content/full/archinternmed.2011.2287

NPR coverage http://www.npr.org/blogs/thesalt/2012/03/12/148457233/death-by-bacon-study-finds-eating-meat-is-risky?sc=fb&cc=fp

To give NPR credit, they cover the article accurately and include the contrasting viewpoints and alternative explanations offered by other researchers known in the field. There were a few points that I took away from both the article and the news coverage that I thought might be interesting talking points.

Correlation of Intake of Dietary Heme and Myocardial Infarction (MI) I had never heard of this! The studies they list to support this statement (references 17-20 in the scholarly article) seem to suggest that the interaction of intake on heme iron and rates of MI is only significant when the highest and lowest quartile of participants were compared, and that overall iron consumption had no association with frequency of MI. What does this mean? Heme iron is bound, not free, and it simply doesn't make sense to me that it should increase the risk of MI. Thoughts?

Listed Covariables The authors also report that increased consumption of red and processed meat also correlated with increased seditivity, decreased intake of fruits, vegetables and whole grains, increased likelihood for smoking, to be obese, etc. It seems to me more likely that these covariables are also confounds to their study. Correct me if I'm wrong, but it seems to me that the authors were unable to adjust their analysis to control for these confounds, or if they did, their findings were non-significant and thus not reported. I find this a bit of an egregious oversite! Again, thoughts?

Quality of Red Meat and PUFA ratio Though the authors state the found mortality rate was slightly attenuated when they controlled for saturated fatty acids (SFAs), and thus suggest that SFAs might act as a mechanism for decreased coronary health. However there is no mention given to the average quality of the meat consumed (was it factory farmed? pastured?) and the possible interaction of oxidized poly-unsaturated fatty acids (PUFAs) after cooking. I think at least addressing the quality of the meat would be a fair point to make, and am frankly surprised the researchers didn't, though given that this study began more than 20 years ago, perhaps it wasn't something that was thought of at it's initiation.

I suppose that this post is really more a wish to start a discussion than pose a direct question. Does this study raise worrying points? Aside from the potential association of Heme Iron and increased risk of MI, the greatest worry I take away is that doctors will be reading this and informing their opinions on what I believe to be poorly conducted and badly substantiated research.

B0454de6d4f4cdd9ca2e59021dc105bf
606 · March 22, 2012 at 12:40 AM

I agree with your point although by "healthier than" you probably mean "less unhealthy" (?). By "modern environment", I mean "polluted environment".

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160 · March 17, 2012 at 2:44 PM

There's no such thing as a model that trends upwards. The raw data is the raw data, and a model estimates coefficients. The "trend" of a model is the coefficient, and that coefficient is calculated by fitting the whole set of data, so to say that the adjusted model does trend upwards is proving my point that the only reason the adjusted model trends upwards is because of the inclusion of the fifth quartile. It's disingenuous for them to present the hazard ratios in the way that they have. It appears that each quartile has that risk, but it's just a manipulation of a single number coefficient.

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218 · March 17, 2012 at 11:52 AM

By "eaten in a modern environment" are you referring to the meat itself, or the way it is processed and turned into just one more ingredient in the SAD? Factory farmed red meat (when it's not turned into hamburger) in a whole food diet is still different to (and healthier than) processed meat products with a mainstream grain/soy/vege-oil diet.

07842fbab8730403ef284e655083fe0e
218 · March 17, 2012 at 11:45 AM

Undeniably? sorry, no. Red meat is not the same as animal-based-processed-meat-products.

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120 · March 16, 2012 at 5:34 PM

I did a sample calculation for unprocessed meat all cause mortality in the health professional follow-up study. and Q2-4 were lower than Q1, however they didn't establish their hazard ratio based on the raw data. The hazard ratios are based on the Adjusted models which do trend upwards. To say they're basing their trend on a outlier is an unfair criticism. Their adjusted model however probably isn't as comprehensive as they'd like to think it is. So the study is probably still flawed.

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2387 · March 15, 2012 at 1:55 PM

And from denise: http://www.marksdailyapple.com/will-eating-red-meat-kill-you/

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2387 · March 15, 2012 at 1:38 PM

Lots of good followup now from Denise... http://www.marksdailyapple.com/will-eating-red-meat-kill-you/

Medium avatar
10234 · March 14, 2012 at 10:44 PM

Duh if you're cognizant of processed meat risk. Otherwise "lady put down that hotdog."

Medium avatar
10234 · March 14, 2012 at 10:24 PM

Red meat is undeniably a cause of increased colorectal cancer. Even paleos have to agree that what is sold in the supermarkets and restaurants - from country ham to breakfast sausage to charred beef from the grill - contains a b!ttload of carcinogens.

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2387 · March 14, 2012 at 5:44 PM

@J.Stanton, great article. FYI in my response above, some have questioned whether I interpretered the "attentuation" correctly, as others read it opposite of how I read it, they say that if the study did adjustments for sat.fat and cholesterol, and then following that the mortality was attenuated, it means (from the point of view of the study) that sat fat and cholesterol CAUSED increased mortality. My take, the study made it a hard statement to interpret :)

21fd060d0796fdb8a4a990441e08eae7
24523 · March 14, 2012 at 2:51 PM

Excellent articles by you and Chris. Controlled studies in nutrition are hard enough for individual nutrients, and nearly impossible for some foods. Adherence is low, nutrient interactions exist, the time course until health effects is too long, etc etc. Therefore, there is a significant portion of academics who simply "do not believe" in nutritional epidemiology.

21fd060d0796fdb8a4a990441e08eae7
24523 · March 14, 2012 at 2:50 PM

Excellent articles by you and Chris. Controlled studies in nutrition are hard enough for individual nutrients, and nearly impossible for some foods. Adherence is low, nutrient interactions exist, the time course until health effects is too long, etc etc. Therefore, there is a significant portion of academic who simply "do not believe" in nutritional epidemiology.

Medium avatar
2913 · March 14, 2012 at 2:47 PM

From seeing all the flack this study has been receiving here and across the web (not just on Paleo sites), it seems like the real title of the study should've stuck with something along the lines of: "Burger with fries and Coke still bad for you."

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2387 · March 14, 2012 at 12:24 PM

Here is a blog that does an in depth analysis that concurs: http://www.zoeharcombe.com/2012/03/red-meat-mortality-the-usual-bad-science/

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2387 · March 14, 2012 at 11:52 AM

@stephen, did you read Roger C's posting further down? Basically he showed how they created a rising trend of mortality with meat usage when the only time there was elevated mortality consumption was in the last quintile, which by the way, is where the associations were strong with smoking, alcohol, lack of exercise, high calorie, etc... and while the study may have adjusted for most of those, we don't know if it merely adjusted individually or for the cumulative effect, and I suspect it wasn't the latter. At least the study does mention the correlation to those as well...

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2387 · March 14, 2012 at 11:50 AM

@stephen, did you read Roger C's posting further down? Yes my words were harsh, but basically he showed how they created a rising trend with meat usage when the only time there was elevated meat consumption was in the last quintile, which by the way, is where the associations were strong with smoking, alcohol, lack of exercise, high calorie, etc... and while the study may have adjusted for most of those, we don't know if it merely adjusted individually or for the cumulative effect, and I suspect it wasn't the latter. At least the study does mention the correlation to those as well...

3b0b95dfc6dc5c18e535945f4aab0866
2387 · March 14, 2012 at 11:46 AM

@antipirate,@elrajajo Ok I may be wrong on that, despite seeing attenuate used in other contexts in other papers that implied differently. After I read through some more I may re-edit appropriately

47988c83c354dff62a93b5d13f5d1c3d
10 · March 14, 2012 at 10:38 AM

@wildwabbit - I'm no expert either but I do think you've got it wrong on this attenuation thing. It seems they are saying that of the increased risk of cvd, a portion may be due to sat fat and cholesterol, after adjusting for this then the total increased risk is attenuated. This doesn't mean that sat fat and cholesterol are protective but that they are independently a risk factor which after adjusting for still leaves the risk of some other element of the meat. Any statisticians in the house?

121a16aded2bed8dca492d3c9662ef4c
1317 · March 14, 2012 at 8:57 AM

Study author Hu pointed out that the risk was highest in people who ate processed meats. The nitrites increase diabetes risk and, once they form nitrosamines, the cancer risk also. I think it's inaccurate and unfair to suggest that study "faked its results." If there is anything that worries me about some paleo adherents, it's the tendency towards the same kind of confirmation bias they accuse others of having. Our goal should be to find the truth, not to make ourselves feel good about our choices at any cost.

Be1dbd31e4a3fccd4394494aa5db256d
17949 · March 14, 2012 at 4:30 AM

It's not so much a weak point as a death knell. Epidemiology is very iffy already and if researchers don't even take well-known confounding factors into account when they can then they are dishonest. If they decide to do a study like this when they know that they can't they are still dishonest. If they decide to try and base policy off of epidemiology they are probably lacking creatine in their brains and need more red meat.

A2c38be4c54c91a15071f82f14cac0b3
12702 · March 14, 2012 at 3:05 AM

I'm with you in being frustrated, though it seems to me it's largely the media who are suggesting the study is "proof" of red meat being deadly. As far as I know the researchers were simply reporting a statistical association.

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2387 · March 14, 2012 at 2:42 AM

Attenuate means "to weaken, diminish" as in how it affects a correlation. They clearly say the correlation was attenuated between red meat and CVD MORTALITY when accounting for saturated fat and cholesterol. And for another weakness in the study check out Roger C's response below, he shows how they essentially faked a rising correlation with mortality as meat servings increased...

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449 · March 14, 2012 at 1:43 AM

had to laugh...the ONLY time i watch the talking heads is when I'm traveling for work.

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160 · March 14, 2012 at 1:08 AM

The tables are the intended source. Look at the lines for "Cases/person-years, No." The negative/flat trend is there for Q1-Q4. They then fit the model including Q5 which, when including, defines the upward trend. Then they take the coefficients from that fitted model and retroactively apply those to the four quintiles, which is why it looks like there's an increasing hazard.

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78422 · March 14, 2012 at 12:57 AM

I'm guessing that I'm not alone in being frustrated with these articles. This is epidemiology. This is used to form hypotheses so we can investigate. They have no business telling the public to stay away from red meat based on such a small bit of data.

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3391 · March 14, 2012 at 12:47 AM

Performing controlled studies is expensive. Torturing an existing data set until it produces the correlations you want is cheap and easy. Just play with the set of covariates you "adjust" for until the desired correlation reaches statistical significance.

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120 · March 14, 2012 at 12:27 AM

I don't think they're offering iron as the main factor correlated with all cause mortality, it's just one possible explanation for PART of the correlation that they suggest exists with red meat

B4661e44912c6f7c5eb26f36d15dd604
120 · March 14, 2012 at 12:24 AM

Yeah this is a major concern with this kind of study particularly if lots of studies keep mining the same data set (like the Nurses' Health Study) What we need is new data.

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120 · March 14, 2012 at 12:18 AM

Yeah the fact that this study didn't have the data to consider Cooking tempature and technique is one of it's weaker points imo

B4661e44912c6f7c5eb26f36d15dd604
120 · March 14, 2012 at 12:13 AM

Currently those links lead to tables, and just looking at the all cause mortality under their multivariate model the mortality seems to increase across all 5 quintiles. I can't find that negative trend.

B4661e44912c6f7c5eb26f36d15dd604
120 · March 13, 2012 at 11:48 PM

"Correct me if I'm wrong, but it seems to me that the authors were unable to adjust their analysis to control for these confounds, or if they did, their findings were non-significant and thus not reported. I find this a bit of an egregious oversite!" After reading the study myself I didn't get this impression, they made adjustments for a whole bunch of covariables. I however am no expert when it comes to statistics so maybe all those adjustments adversely affect the quality of their data.

B4661e44912c6f7c5eb26f36d15dd604
120 · March 13, 2012 at 11:34 PM

However the simple existence of these correlations is not enough to invalidate the findings of this study. Personally I want this study to be wrong but I don't know enough about statistics to really assess it's potential weak points.

B4661e44912c6f7c5eb26f36d15dd604
120 · March 13, 2012 at 11:32 PM

I don't understand how you come to the conclusion you do in your second paragraph the attenuation they mention suggests not that saturated fat and cholesterol are protective but that they are responsible for part of the CVD risk that is seen in high meat consumers. They do point out a number of correlations between red meat consumption and other unhealthy habits but they make an effort to adjust for many of these factors.One could suggest that their adjustments aren't going to be good enough, or that there are important factors they haven't adjusted for(quality of meat cooking practices)...

Be1dbd31e4a3fccd4394494aa5db256d
17949 · March 13, 2012 at 11:31 PM

You are definitely right and I didn't say that in the post but I definitely knew it. And because epidemiology is riddled with confounding factors I can't say that it necessarily had to do with grass-fed, but I consider that study to be grounds for the hypothesis that CLA or something else in grass-fed beef is protective.

A2c38be4c54c91a15071f82f14cac0b3
12702 · March 13, 2012 at 9:51 PM

This of course assumes that the the researchers accounted for any possible difference in all those foods that could possibly affect mortality. There are obviously confounding factors, but a basic trend is there. I'm not even trying to argue it's correct, I'm just saying I understand how they came to that conclusion

A2c38be4c54c91a15071f82f14cac0b3
12702 · March 13, 2012 at 9:51 PM

This of course assumes that the the researchers accounted for any possible difference in all those foods that could possibly affect mortality. There are obviously confounding factors, but a basic trend is there. I'm not even trying to argue it's correct, I'm just saying understand how they came to that conclusion.

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24538 · March 13, 2012 at 8:23 PM

"in Australia there was no association between any red meat and colon cancer risk"--This seems like an important difference because 20 years ago, grass finished beef was unheard of in the States, but I'm pretty sure, in Australia cattle has always been finished on pasture.

9d43f6873107e17ca4d1a5055aa7a2ad
56616 · March 13, 2012 at 7:34 PM

++ I use FFQs for my own self-tracking and they are pretty damn unreliable. Sometimes I'll forget to fill them out for a few days and at that point that data is useless. What are the odds if I can remember whether or not I ate grains three days ago? They were asked once a YEAR.

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2387 · March 13, 2012 at 6:31 PM

Very astute find! This study reeks more of rotten red meat the more people look into it!

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78422 · March 13, 2012 at 5:15 PM

Mscott - If Iron=risk for mortality than we should expect to see that the lower the iron the better. 400kcal of chicken has 1mg less iron than a steak. Milk, grains and legumes are largely free of free-iron. Yet they don't help a corresponding amount. So barely reducing iron = better results than lowering it drastically? No.

Medium avatar
10234 · March 13, 2012 at 4:05 PM

@mascott Col. Sanders outlived Dr. Atkins by 25%. Same fatty diets, same overweight appearance in old age. Advantage chicken.

Medium avatar
10234 · March 13, 2012 at 3:58 PM

On an N=1 level you're better off working on reducing your own risk factors. If you have high A1C, blood sugar, weight or waistline, or blood pressure, changing these correlators can affect your personal causation. Eliminating red meat is way down the list of useful action steps.

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220 · March 13, 2012 at 3:30 PM

Nice job. It's a fairly nice J curve. Highest risk is in 1st and 5th quintiles.

D1728f99db66ff91d695a6df5cd38b02
1363 · March 13, 2012 at 3:25 PM

my bf sent me the link the these oh so knowledgeable news items *sigh*. rant /rant that's how I feel. I like to share.

11b7b7ba720a5cd43c74a0ef99a16adb
3450 · March 13, 2012 at 2:40 PM

People that ignore the govt's advice about avoiding high fat foods (like red meat), are likely to ignore ALL of the govt's advice about healthy choices. So, someone that eats lots of red meat is also probably more likely to: not exercise, smoke, drink to excess, eat fast food, and in general live an unhealthy lifestyle. In this case, red meat isn't the root cause, it's a symptom of a bigger problem: a person that doesn't take care of themselves.

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3651 · March 13, 2012 at 12:05 PM

Those are all good examples of why studies are dangerous.

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843 · March 13, 2012 at 10:32 AM

Some even funnier points. People with heart disease and diabetes had low cholesterol completely diametrically opposite to what the medical establishment would have us believe. People eating high meat (or whatever was put into the meat box), were also eating a lot of vegetables. Funny they didn't say that vegetables were bad for us :-).

A2c38be4c54c91a15071f82f14cac0b3
12702 · March 13, 2012 at 6:31 AM

How are their results inconsistent with what they're saying? Chicken has less heme iron and resulted in a 14% improvement in mortality.

64433a05384cd9717c1aa6bf7e98b661
15226 · March 13, 2012 at 3:41 AM

great points you brought up!

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4359 · March 13, 2012 at 3:38 AM

I like your answer. Basically, it's a self-fulfilling fuck up of massive proportions. For 50 years, the government, the American Heart Association, and Big Agriculture, Big Pharma, and the Big Crap Food industries have been selling Americans on the story that saturated fat and red meat will kill them. It is no longer possible to control for confounding effects because the whole damn data set is confounded.

4781cf8ae1bfcb558dfb056af17bea94
4359 · March 13, 2012 at 3:31 AM

It is not well known that dietary iron is inflammatory because it is not true.

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4875 · March 13, 2012 at 3:27 AM

I seem to be agreeing with you repeatedly today DFH. Quit makin' so much sense. :)

0d0842381492a41b2173a04014aae810
4875 · March 13, 2012 at 3:26 AM

I seem to be agreeing with you repeatedly today DFH. Quit talkin' so much sense. :)

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18635 · March 13, 2012 at 1:43 AM

In the end it has no relevant actionable points at this time, but in the future perhaps in conjunction with some other studies the data it provided may be evaluated in a different light and enhance our knowledge base. Or not.....

E0250b1e6dc5ec1539ffb745042b4d80
3651 · March 13, 2012 at 1:11 AM

Studies are bad for you. Red meat is fine. :)

9e056e33ffc978a1d3ecb8c3d01cc6b6
100 · March 13, 2012 at 1:06 AM

Well from my understanding, the study was correlational not experimental in design, so they compared groups who ate predominately red meat and groups who ate red meat and other protein sources, and found a statistically-significant decrease in their mortality rates. However the covariables listed with the high-red-meat-consumers (what I find to be potential confonds) were not listed with the moderate-red-meat-eaters, making the findings more questionable to me, I think.

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3651 · March 13, 2012 at 1:03 AM

The problem is still the people in studies like that don't eat well anyway, so it's all a train wreck study.

D7cc4049bef85d1979efbd853dc07c8e
4029 · March 13, 2012 at 1:02 AM

They also noted that overcooking the meat could be a confounder. Seems like hamburger (on a bun?) is counted as red meat.

9e056e33ffc978a1d3ecb8c3d01cc6b6
100 · March 13, 2012 at 12:44 AM

Well no not exactly, they also found the mortality rate was decreased when a frequency of red meat was decreased and replaced with an alternate protein source, though they admit they were unable to examine the relationship between lean vs fatty meats.

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3b0b95dfc6dc5c18e535945f4aab0866
26
2387 · March 13, 2012 at 3:17 AM

Reading this table of lifestyle data from the study is mind blowing: http://archinte.ama-assn.org/cgi/content-nw/full/archinternmed.2011.2287v1/IOI110027T1

Essentially, those with highest rates of red meat have the lifestyle of someone who goes to bars for lunch and dinner to have a smoke and beer/martini with their hamburger w/fries and no veggies, which substitutes for their social life because they aren't getting out for exercise.

But the researchers rush out to pin the blame on red meat.

Quotes from the study: "The association between red meat and CVD mortality was moderately attenuated after further adjustment for saturated fat and cholesterol, suggesting a mediating role for these nutrients." Which basically says saturated fat and cholesterol was mildly protective to whatever else was causing the CVD. [EDIT: my interpretation is disputed - it could have meant that by attempting to adjust out the influence of sat fat and cholesterol, the result appears as mortality moderately going down] This is a mind blowing statement, because people have always accused those two items in red meat of causing CVD but here they essentially gloss over their own point that it is mildly protective. Well, if thats so, then WHAT in red meat could be causing CVD???

Or...again could it be the unhealthy lifestyle, again quoting from the study:"Men and women with higher intake of red meat were less likely to be physically active and were more likely to be current smokers, to drink alcohol, and to have a higher body mass index (Table 1). In addition, a higher red meat intake was associated with a higher intake of total energy but lower intakes of whole grains, fruits, and vegetables." Which plays into the profile I stated above.

EDIT: Also, the table above shows the people consuming the most red and processed meat have the lowest % of high cholesterol. Yet another confounder because we all know our paleo lifestyle doesn't reduce cholesterol necessarily, but that we will see reduced cholesterol in half of those that do have heart disease. Again a clear lifestyle marker that goes against the conventional wisdom here in the data.

EDIT: List of bloggers analyses that, way better than I explained above, shred the study.

11b7b7ba720a5cd43c74a0ef99a16adb
3450 · March 13, 2012 at 2:40 PM

People that ignore the govt's advice about avoiding high fat foods (like red meat), are likely to ignore ALL of the govt's advice about healthy choices. So, someone that eats lots of red meat is also probably more likely to: not exercise, smoke, drink to excess, eat fast food, and in general live an unhealthy lifestyle. In this case, red meat isn't the root cause, it's a symptom of a bigger problem: a person that doesn't take care of themselves.

4781cf8ae1bfcb558dfb056af17bea94
4359 · March 13, 2012 at 3:38 AM

I like your answer. Basically, it's a self-fulfilling fuck up of massive proportions. For 50 years, the government, the American Heart Association, and Big Agriculture, Big Pharma, and the Big Crap Food industries have been selling Americans on the story that saturated fat and red meat will kill them. It is no longer possible to control for confounding effects because the whole damn data set is confounded.

B4661e44912c6f7c5eb26f36d15dd604
120 · March 13, 2012 at 11:34 PM

However the simple existence of these correlations is not enough to invalidate the findings of this study. Personally I want this study to be wrong but I don't know enough about statistics to really assess it's potential weak points.

34cf7065a6c94062c711eb16c0f6adc3
843 · March 13, 2012 at 10:32 AM

Some even funnier points. People with heart disease and diabetes had low cholesterol completely diametrically opposite to what the medical establishment would have us believe. People eating high meat (or whatever was put into the meat box), were also eating a lot of vegetables. Funny they didn't say that vegetables were bad for us :-).

3b0b95dfc6dc5c18e535945f4aab0866
2387 · March 14, 2012 at 2:42 AM

Attenuate means "to weaken, diminish" as in how it affects a correlation. They clearly say the correlation was attenuated between red meat and CVD MORTALITY when accounting for saturated fat and cholesterol. And for another weakness in the study check out Roger C's response below, he shows how they essentially faked a rising correlation with mortality as meat servings increased...

3b0b95dfc6dc5c18e535945f4aab0866
2387 · March 14, 2012 at 11:50 AM

@stephen, did you read Roger C's posting further down? Yes my words were harsh, but basically he showed how they created a rising trend with meat usage when the only time there was elevated meat consumption was in the last quintile, which by the way, is where the associations were strong with smoking, alcohol, lack of exercise, high calorie, etc... and while the study may have adjusted for most of those, we don't know if it merely adjusted individually or for the cumulative effect, and I suspect it wasn't the latter. At least the study does mention the correlation to those as well...

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120 · March 13, 2012 at 11:32 PM

I don't understand how you come to the conclusion you do in your second paragraph the attenuation they mention suggests not that saturated fat and cholesterol are protective but that they are responsible for part of the CVD risk that is seen in high meat consumers. They do point out a number of correlations between red meat consumption and other unhealthy habits but they make an effort to adjust for many of these factors.One could suggest that their adjustments aren't going to be good enough, or that there are important factors they haven't adjusted for(quality of meat cooking practices)...

3b0b95dfc6dc5c18e535945f4aab0866
2387 · March 14, 2012 at 11:46 AM

@antipirate,@elrajajo Ok I may be wrong on that, despite seeing attenuate used in other contexts in other papers that implied differently. After I read through some more I may re-edit appropriately

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15226 · March 13, 2012 at 3:41 AM

great points you brought up!

121a16aded2bed8dca492d3c9662ef4c
1317 · March 14, 2012 at 8:57 AM

Study author Hu pointed out that the risk was highest in people who ate processed meats. The nitrites increase diabetes risk and, once they form nitrosamines, the cancer risk also. I think it's inaccurate and unfair to suggest that study "faked its results." If there is anything that worries me about some paleo adherents, it's the tendency towards the same kind of confirmation bias they accuse others of having. Our goal should be to find the truth, not to make ourselves feel good about our choices at any cost.

3b0b95dfc6dc5c18e535945f4aab0866
2387 · March 15, 2012 at 1:38 PM

Lots of good followup now from Denise... http://www.marksdailyapple.com/will-eating-red-meat-kill-you/

47988c83c354dff62a93b5d13f5d1c3d
10 · March 14, 2012 at 10:38 AM

@wildwabbit - I'm no expert either but I do think you've got it wrong on this attenuation thing. It seems they are saying that of the increased risk of cvd, a portion may be due to sat fat and cholesterol, after adjusting for this then the total increased risk is attenuated. This doesn't mean that sat fat and cholesterol are protective but that they are independently a risk factor which after adjusting for still leaves the risk of some other element of the meat. Any statisticians in the house?

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2387 · March 14, 2012 at 11:52 AM

@stephen, did you read Roger C's posting further down? Basically he showed how they created a rising trend of mortality with meat usage when the only time there was elevated mortality consumption was in the last quintile, which by the way, is where the associations were strong with smoking, alcohol, lack of exercise, high calorie, etc... and while the study may have adjusted for most of those, we don't know if it merely adjusted individually or for the cumulative effect, and I suspect it wasn't the latter. At least the study does mention the correlation to those as well...

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17949 · March 13, 2012 at 5:15 AM

Well just really quickly my take:

The relative risk was small, in epidemiology this is hardly anything to talk about. But controlling for saturated fat is an interesting bit. Thanks for that.

Cooking tempature and technique matters. They didn't control for it. Just an example of health effects (well not effects because it's epidemiology...associations) of overcooking, in Australia there was no association between any red meat and colon cancer risk, however baking it was associated with a substantial reduction in risk compared with other techniques http://www.ncbi.nlm.nih.gov/pubmed/21364608 Pretty important if we're talking about meat. I think that the toxins formed from high heat cooking can potentially oxidize cholesterol in the bloodstream, and can definitely cause systemic inflammation.

In a subset of the population heme iron can accumulate and cause all sorts of oxidative stress. That is a subset. In general it is damaging but it isn't really when there is sufficient vitamin e from food sources and other antioxidants. Context, right? The general population is deficient in many nutrients, especially vitamin e, probably more for the people eating the most red meat. Those who tend to store too much iron should either cut down on their red meat intake, increase their antioxidants, or give blood. Probably all of those. The rest of us...eh attend to your iron and antioxidant levels as you see fit. Lower isn't necessarily better. Tannins in coffee or tea and calcium also inhibit the absorption. Actually there's lots one can do. Chlorophyll in the same meal can protect the GI tract, but general antioxidant intake is probably sufficient. Meat + vegetables + calcium is my policy.

There are factors that can't be controlled for. Red meat is very calming and satisfying. People who eat more of it might be more stressed out and seeking it as a remedy.

Etc etc. Given the cooking thing from the evidence I have seen where cooking technique greatly attenuates or even reverses an association with cancers, I can't see this being good evidence for anything. Not knocking the authors, though, they have provided a good study that should be taken for what it actually shows.

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17949 · March 13, 2012 at 11:31 PM

You are definitely right and I didn't say that in the post but I definitely knew it. And because epidemiology is riddled with confounding factors I can't say that it necessarily had to do with grass-fed, but I consider that study to be grounds for the hypothesis that CLA or something else in grass-fed beef is protective.

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120 · March 14, 2012 at 12:18 AM

Yeah the fact that this study didn't have the data to consider Cooking tempature and technique is one of it's weaker points imo

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24538 · March 13, 2012 at 8:23 PM

"in Australia there was no association between any red meat and colon cancer risk"--This seems like an important difference because 20 years ago, grass finished beef was unheard of in the States, but I'm pretty sure, in Australia cattle has always been finished on pasture.

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17949 · March 14, 2012 at 4:30 AM

It's not so much a weak point as a death knell. Epidemiology is very iffy already and if researchers don't even take well-known confounding factors into account when they can then they are dishonest. If they decide to do a study like this when they know that they can't they are still dishonest. If they decide to try and base policy off of epidemiology they are probably lacking creatine in their brains and need more red meat.

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160 · March 13, 2012 at 2:27 PM

Here are the key takeaways, direct from the published article:

ASSESSMENT OF MEAT CONSUMPTION

In 1980, a 61-item FFQ was administered to the NHS participants to collect information about their usual intake of foods and beverages in the previous year. In 1984, 1986, 1990, 1994, 1998, 2002, and 2006, similar but expanded FFQs with 131 to 166 items were sent to these participants to update their diet. Using the expanded FFQ used in the NHS, dietary data were collected in 1986, 1990, 1994, 1998, 2002, and 2006 from the HPFS participants

So they based the study off of surveys given every four years.

Now, take a look at the charts included with the study that show cases of mortality against red meat consumption (grouped by quintiles of consumption):

http://archinte.ama-assn.org/cgi/content-nw/full/archinternmed.2011.2287v1/IOI110027T2 http://archinte.ama-assn.org/cgi/content-nw/full/archinternmed.2011.2287v1/IOI110027T3 http://archinte.ama-assn.org/cgi/content-nw/full/archinternmed.2011.2287v1/IOI110027T4

Notice anything?

The trend for cases of mortality is actually flat (or slightly negative!) for quintiles 1 through 4. It's only Q5 which establishes the trend line for being positive! Now why do the hazard ratios keep going up in each quintile?

We estimated the associations of substituting 1 serving of an alternative food for red meat with mortality by including both as continuous variables in the same multivariate model, which also contained nondietary covariates and total energy intake. The difference in their ?? coefficients and in their own variances and covariance were used to estimate the hazard ratios (HRs) and 95% CIs for the substitution associations.

They determined the hazard ratios from the fitted line, which as we saw above, only has a trend because of the last quintile! It is pretty misleading the way the data is presented!

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2387 · March 14, 2012 at 12:24 PM

Here is a blog that does an in depth analysis that concurs: http://www.zoeharcombe.com/2012/03/red-meat-mortality-the-usual-bad-science/

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120 · March 14, 2012 at 12:13 AM

Currently those links lead to tables, and just looking at the all cause mortality under their multivariate model the mortality seems to increase across all 5 quintiles. I can't find that negative trend.

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56616 · March 13, 2012 at 7:34 PM

++ I use FFQs for my own self-tracking and they are pretty damn unreliable. Sometimes I'll forget to fill them out for a few days and at that point that data is useless. What are the odds if I can remember whether or not I ate grains three days ago? They were asked once a YEAR.

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220 · March 13, 2012 at 3:30 PM

Nice job. It's a fairly nice J curve. Highest risk is in 1st and 5th quintiles.

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2387 · March 13, 2012 at 6:31 PM

Very astute find! This study reeks more of rotten red meat the more people look into it!

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2387 · March 15, 2012 at 1:55 PM

And from denise: http://www.marksdailyapple.com/will-eating-red-meat-kill-you/

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160 · March 14, 2012 at 1:08 AM

The tables are the intended source. Look at the lines for "Cases/person-years, No." The negative/flat trend is there for Q1-Q4. They then fit the model including Q5 which, when including, defines the upward trend. Then they take the coefficients from that fitted model and retroactively apply those to the four quintiles, which is why it looks like there's an increasing hazard.

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120 · March 16, 2012 at 5:34 PM

I did a sample calculation for unprocessed meat all cause mortality in the health professional follow-up study. and Q2-4 were lower than Q1, however they didn't establish their hazard ratio based on the raw data. The hazard ratios are based on the Adjusted models which do trend upwards. To say they're basing their trend on a outlier is an unfair criticism. Their adjusted model however probably isn't as comprehensive as they'd like to think it is. So the study is probably still flawed.

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160 · March 17, 2012 at 2:44 PM

There's no such thing as a model that trends upwards. The raw data is the raw data, and a model estimates coefficients. The "trend" of a model is the coefficient, and that coefficient is calculated by fitting the whole set of data, so to say that the adjusted model does trend upwards is proving my point that the only reason the adjusted model trends upwards is because of the inclusion of the fifth quartile. It's disingenuous for them to present the hazard ratios in the way that they have. It appears that each quartile has that risk, but it's just a manipulation of a single number coefficient.

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3651 · March 13, 2012 at 12:30 AM

Basically what they figured out is that a lot of people have a crap diet and they don't know what to blame it on, so pick one...

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4029 · March 13, 2012 at 1:02 AM

They also noted that overcooking the meat could be a confounder. Seems like hamburger (on a bun?) is counted as red meat.

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18635 · March 13, 2012 at 1:43 AM

In the end it has no relevant actionable points at this time, but in the future perhaps in conjunction with some other studies the data it provided may be evaluated in a different light and enhance our knowledge base. Or not.....

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100 · March 13, 2012 at 12:44 AM

Well no not exactly, they also found the mortality rate was decreased when a frequency of red meat was decreased and replaced with an alternate protein source, though they admit they were unable to examine the relationship between lean vs fatty meats.

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4875 · March 13, 2012 at 3:27 AM

I seem to be agreeing with you repeatedly today DFH. Quit makin' so much sense. :)

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3651 · March 13, 2012 at 1:03 AM

The problem is still the people in studies like that don't eat well anyway, so it's all a train wreck study.

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3391 · March 13, 2012 at 8:07 PM

EDIT TO ADD: I've just written a comprehensive response here: Always Be Skeptical Of Nutrition Headlines: Or, What "Red Meat Consumption and Mortality" (Pan et.al.) Really Tells Us

(It incorporates, and credits, a couple of the responses from this page.)

Original answer:

Everyone calm down and take a deep breath. Now, note that the data used is from the Nurses' Health Study. Chris Masterjohn covered this a while ago, last time this data was mined:

"Will Eating Meat Make Us Die Younger?"
http://blog.cholesterol-and-health.com/2009/03/will-eating-meat-make-us-die-younger.html

"Focusing on the second questionnaire, we found that butter, whole milk, eggs, processed meat, and cold breakfast cereal were underestimated by 10 to 30% on the questionnaire. In contrast, a number of fruits and vegetables, yoghurt and fish were overestimated by at least 50%. These findings for specific foods suggest that participants over-reported consumption of foods often considered desirable or healthy, such as fruit and vegetables, and underestimated foods considered less desirable."

In other words, the already-proven inaccuracy of the data set is far greater than the negative effect claimed for red meat.

JS

(Also, Roger C's statistical analysis is good.)

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3391 · March 14, 2012 at 12:47 AM

Performing controlled studies is expensive. Torturing an existing data set until it produces the correlations you want is cheap and easy. Just play with the set of covariates you "adjust" for until the desired correlation reaches statistical significance.

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120 · March 14, 2012 at 12:24 AM

Yeah this is a major concern with this kind of study particularly if lots of studies keep mining the same data set (like the Nurses' Health Study) What we need is new data.

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24523 · March 14, 2012 at 2:50 PM

Excellent articles by you and Chris. Controlled studies in nutrition are hard enough for individual nutrients, and nearly impossible for some foods. Adherence is low, nutrient interactions exist, the time course until health effects is too long, etc etc. Therefore, there is a significant portion of academic who simply "do not believe" in nutritional epidemiology.

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24523 · March 14, 2012 at 2:51 PM

Excellent articles by you and Chris. Controlled studies in nutrition are hard enough for individual nutrients, and nearly impossible for some foods. Adherence is low, nutrient interactions exist, the time course until health effects is too long, etc etc. Therefore, there is a significant portion of academics who simply "do not believe" in nutritional epidemiology.

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2387 · March 14, 2012 at 5:44 PM

@J.Stanton, great article. FYI in my response above, some have questioned whether I interpretered the "attentuation" correctly, as others read it opposite of how I read it, they say that if the study did adjustments for sat.fat and cholesterol, and then following that the mortality was attenuated, it means (from the point of view of the study) that sat fat and cholesterol CAUSED increased mortality. My take, the study made it a hard statement to interpret :)

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605 · March 13, 2012 at 3:54 PM

The answer is the same every single time this issue comes up. These studies are worthless because correlation does not prove causation. There are way too many variables involved in human health to simply compare meat consumption to CVD events and expect a scientific outcome.

For example, when you go to a fast food restaurant the majority of the calories you get are carbs. The soda is carbs, the fries are carbs, and the bun is carbs. The only meat is the small little patty they give you, which, depending on the chain, can be as small as 1/8th a pound. Unless you're eating a steak, chances are your meat is accompanied by a large amount of carbs, which contribute to heart disease.

There is also the fact that people who are trying to be healthy and do things such as stop smoking, minimize alcohol, avoid candies and sodas, exercise more, get proper sleep, etc, in addition to eating less meat because that's what they're told they need to do to be healthy. These kinds of studies do not even make an attempt to try and isolate for these extremely influential variables, which makes their conclusions pretty worthless towards practical application.

Has anyone ever seen a study that shows a high meat/low carb diet to result in higher CVD events than a low meat/high carb diet? No? Exactly.

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21405 · March 13, 2012 at 12:12 PM

I heard about this watching the news this morning (I'm in a hotel, which means it's the only time I bother with watching the news).

On CNN, the two anchor mavens were harping about how they LOVE eating red meat and bacon... how it was some kind of forbidden fruit and they try to resist the temptation to eat it - then they segue to another newswoman who apparently eats bacon every morning, and they were making cracks about how thin she was, but how she's gonna die.

Her response was "yeah, Sanjay (Dr. Sanjay Gupta, I'm assuming) keeps harassing me about my morning bacon intake but I just ignore him." I wanted to high-five her through the TV.

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449 · March 14, 2012 at 1:43 AM

had to laugh...the ONLY time i watch the talking heads is when I'm traveling for work.

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1443 · March 13, 2012 at 3:32 AM

I agree with everyone here. When a person is eating grain fed hamburger with a lot of artificial fillers in it, then chowing it down with coke, then going out to take a smoke.. there are way too many factors to pin down as the root cause.

Correlation not causation

Medium avatar
10234 · March 13, 2012 at 3:58 PM

On an N=1 level you're better off working on reducing your own risk factors. If you have high A1C, blood sugar, weight or waistline, or blood pressure, changing these correlators can affect your personal causation. Eliminating red meat is way down the list of useful action steps.

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37187 · March 13, 2012 at 3:43 PM

Primo Health Coach beat me to it above, but Chris Kresser tweeted that link and Robb Wolf indicatedhe's going to do a post about it.

I commented last night that you could read the study to say red meat causes smoking, drinking and avoidance of exercise.

I do happen to believe that intake of vegetables and fruit is very healthy, but meat is the foundation of my diet and that's not going to change.

It seemed every "news" site trumpeted this stupid study yesterday and I am disheartened by how many people--including young adults whose health could be affected for decades--will read those articles and take them for gospel.

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30 · March 13, 2012 at 8:34 PM

The study shouldn't be dismissed, but the most telling thing is Table 1. Table 1

Just look at how unhealthy lifestyles the 5th quintile compared to the 1st. They are gluttons, who aren't active, smoke more, eat more crap, etc. Big shock that they are 20% more likely to die of disease in 20 years than their healthy lifestyle co-workers.

Others have mentioned that the worst quintile has lower cholesterol which is interesting, but also they have roughly the same BMI, but eat a lot more calories than their counter part and are less active. A little confusing there...

In the womens' study, the 5th ate almost twice as much food as the first, were much less active and yet had roughly the same BMI. Therefore, either 1) the fifth quintile must be full of tall people or people with really high resting metabolism, or 2) the first quintile must be full of women that underestimate what they eat. There is clearly something strange here.

If it's 1), then it's already been shown that eating more calories leads to higher rate of mortality--they presumably controlled for that. Also, it's been shown that tall people don't live as long as short people--don't think they controlled for that--5 or 6 years less IIRC. If it's 2), well, that's the problem with the survey studies in the first place--people can't recall accurately or lie sometimes.

According to their results people that say they eat less red meat have lower rates of CVD and cancer. Concluding from this data, that people can lower their risk by eating less red meat is equivalent telling people to lie about their red meat intake to lower their risk. Since, as so many have said, there is no causality shown here only correlation. Perhaps you don't have to forgo the steak, just tell everyone it's chicken ;)

EDIT: sorry to keep adding to this, but I think it's worth mentioning that using the same data (as poor as it may be), this study found that increased carbs are a culprit in CVD. I wonder what the finding would be if they controlled carbs as a confounder, which it doesn't look like they did. Also, as many have suggested it could be a synergy of variables in the western diet that leads to disease and not a single gunman.

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941 · March 13, 2012 at 7:50 PM

My take from reading the NPR article is that variety is king. They say to reduce intake of processed meats. Duh! they also say that eating a variety of protein sources is healthier. Well that goes back to the "eat fish twice a week" rule that most of us learned as kids.

Several people have pointed out cooking techniques as a contributing factor. One other problem is they did not separate whole foods from conventional. The nutrient profiles and fat profiles of pastured animals, raised without hormone injections or antibiotics to make them bigger, are different from those of animals raised in feed lots. If red meat was so bad, then how did the Lakota live longer, healthier lives than white men 200 years ago when their diet was primarily red meat?

Medium avatar
10234 · March 14, 2012 at 10:44 PM

Duh if you're cognizant of processed meat risk. Otherwise "lady put down that hotdog."

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606 · March 14, 2012 at 12:56 AM

It seems few people here are open to the possibility that there is a real effect here. Sure there may be many methodological problems and flawed interpretation of data, which are easy to trot out if you don't like the findings of this study. But let's not be too quick to dismiss. Paleo peops ate red meat but they lived in a completely different world; the meat was different, the environment was different, and they were mostly healthy.

So, yeah, keep an open mind. It's completely plausible that any amount of farm industry red meat eaten in a modern environment can make you sick in the long-term.

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218 · March 17, 2012 at 11:52 AM

By "eaten in a modern environment" are you referring to the meat itself, or the way it is processed and turned into just one more ingredient in the SAD? Factory farmed red meat (when it's not turned into hamburger) in a whole food diet is still different to (and healthier than) processed meat products with a mainstream grain/soy/vege-oil diet.

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606 · March 22, 2012 at 12:40 AM

I agree with your point although by "healthier than" you probably mean "less unhealthy" (?). By "modern environment", I mean "polluted environment".

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20 · March 13, 2012 at 11:16 AM

Red meat could just be a marker for a not optimal diet. Yet several articles found that replacing processed meat, such as spam, but not unprocessed red meat is already helpful. What is even better is replacement of red meat by fish or poultry and the best choice seems to be replacing all animal protein by protein from plant sources.

Diabetes Care. 2011 May;34(5):1150-6. Epub 2011 Apr 4. Diet-quality scores and the risk of type 2 diabetes in men. CONCLUSIONS: Several diet-quality scores were associated with a lower risk of type 2 diabetes and reflect a common dietary pattern characterized by high intakes of plant-based foods such as whole grains; moderate alcohol; and low intakes of red and processed meat, sodium, sugar-sweetened beverages, and trans fat. High-quality diets may yield the greatest reduction in diabetes cases when followed by those with a high BMI. PMID: 21464460

Diabetes Metab. 2010 Dec;36(6 Pt 1):484-90. Long-term animal-protein consumption is associated with an increased prevalence of diabetes among the elderly: the Mediterranean Islands (MEDIS) study. CONCLUSION: Animal-protein consumption was associated with a higher prevalence of diabetes among the elderly, whereas protein intakes, especially from plant sources, within the recommended range appear to confer considerable protection. This suggests that reducing or controlling the burden of diabetes through dietary means in the elderly should include monitoring their daily protein intake. Copyright ?? 2010 Elsevier Masson SAS. All rights reserved. PMID: 20888279

Am J Clin Nutr. 2012 Mar;95(3):752-8. Epub 2012 Jan 25. Associations of processed meat and unprocessed red meat intake with incident diabetes: the Strong Heart Family Study. CONCLUSION: The consumption of processed meat, such as spam, but not unprocessed red meat, was associated with higher risk of diabetes in AIs, a rural population at high risk of diabetes and with limited access to healthy foods. PMID: 22277554

Stroke. 2012 Mar;43(3):637-44. Epub 2011 Dec 29. Dietary protein sources and the risk of stroke in men and women. CONCLUSIONS: These data suggest that stroke risk may be reduced by replacing red meat with other dietary sources of protein. PMID: 22207512

Am J Clin Nutr. 2011 Oct;94(4):1088-96. Epub 2011 Aug 10. Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. We estimated that substitutions of one serving of nuts, low-fat dairy, and whole grains per day for one serving of red meat per day were associated with a 16-35% lower risk of T2D. CONCLUSION: Our results suggest that red meat consumption, particularly processed red meat, is associated with an increased risk of T2D. PMID: 21831992

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3651 · March 13, 2012 at 12:05 PM

Those are all good examples of why studies are dangerous.

Medium avatar
10234 · March 14, 2012 at 10:24 PM

Red meat is undeniably a cause of increased colorectal cancer. Even paleos have to agree that what is sold in the supermarkets and restaurants - from country ham to breakfast sausage to charred beef from the grill - contains a b!ttload of carcinogens.

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218 · March 17, 2012 at 11:45 AM

Undeniably? sorry, no. Red meat is not the same as animal-based-processed-meat-products.

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606 · March 13, 2012 at 9:11 AM

Here???s a scary ???what if???. What if the association is real but the underlying cause is actually the chemicals which are added to meat (antibiotic and drug residues). I don???t think that???s mentioned in the study as a possible confounder.

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15226 · March 13, 2012 at 4:26 AM

very interesting that in both studies the people who had the most consumption had the lowest occurrence of high cholesterol!

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78422 · March 13, 2012 at 3:42 AM

I don't really get how they blame iron. I read this and they found that changing from Red meat to other protein decreased mortality. However switching to chicken improved it by 14% while grains and dairy only 10% (this is from memory sorry if I get it wrong). The issue is that if iron is a problem then we should expect to see Red meat --> Chicken --> Grains --> Dairy. I think the conclusion that it is the iron isn't supported by the data. Also, didn't they find that the higher the cholestrol and fat the less of a problem it was, rather than the greater?

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12702 · March 13, 2012 at 9:51 PM

This of course assumes that the the researchers accounted for any possible difference in all those foods that could possibly affect mortality. There are obviously confounding factors, but a basic trend is there. I'm not even trying to argue it's correct, I'm just saying I understand how they came to that conclusion

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78422 · March 14, 2012 at 12:57 AM

I'm guessing that I'm not alone in being frustrated with these articles. This is epidemiology. This is used to form hypotheses so we can investigate. They have no business telling the public to stay away from red meat based on such a small bit of data.

Medium avatar
10234 · March 13, 2012 at 4:05 PM

@mascott Col. Sanders outlived Dr. Atkins by 25%. Same fatty diets, same overweight appearance in old age. Advantage chicken.

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78422 · March 13, 2012 at 5:15 PM

Mscott - If Iron=risk for mortality than we should expect to see that the lower the iron the better. 400kcal of chicken has 1mg less iron than a steak. Milk, grains and legumes are largely free of free-iron. Yet they don't help a corresponding amount. So barely reducing iron = better results than lowering it drastically? No.

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12702 · March 13, 2012 at 6:31 AM

How are their results inconsistent with what they're saying? Chicken has less heme iron and resulted in a 14% improvement in mortality.

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12702 · March 13, 2012 at 9:51 PM

This of course assumes that the the researchers accounted for any possible difference in all those foods that could possibly affect mortality. There are obviously confounding factors, but a basic trend is there. I'm not even trying to argue it's correct, I'm just saying understand how they came to that conclusion.

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120 · March 14, 2012 at 12:27 AM

I don't think they're offering iron as the main factor correlated with all cause mortality, it's just one possible explanation for PART of the correlation that they suggest exists with red meat

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12702 · March 14, 2012 at 3:05 AM

I'm with you in being frustrated, though it seems to me it's largely the media who are suggesting the study is "proof" of red meat being deadly. As far as I know the researchers were simply reporting a statistical association.

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980 · March 14, 2012 at 12:06 PM

For many years now CW has said that meat, especially red meat is unhealthy. This alone would lead to this result. Health conscious people would be less likely to eat red meat and more likely to live a healthy lifestyle. And not just "healthy" in those factors that were controlled for, but in many small ways that are almost unmeasureable.

Just look at the original large, observational study of estrogen replacement that showed how it improved health, and then when a controlled study was conducted it showed a strong negative effect. Public perception of the health of an item causes a very strong effect in the outcome of large observational studies.

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110 · March 13, 2012 at 3:41 PM

https://www.facebook.com/ObesityPPMLLC

This is a case of correlation being confused for causation.

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0
2024 · March 13, 2012 at 12:51 AM

No answers, but I too am curious about this. I can see the flaws in a lot of studies, but I'm not well-versed enough in science to be able to see them in this. Or rather, I don't really understand how one adjusts for the many variables and is able to then "swap out" proteins to see what the results are. And because I just.do.not.understand that, I don't really know how to assess the study.

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4875 · March 13, 2012 at 3:26 AM

I seem to be agreeing with you repeatedly today DFH. Quit talkin' so much sense. :)

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3651 · March 13, 2012 at 1:11 AM

Studies are bad for you. Red meat is fine. :)

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100 · March 13, 2012 at 1:06 AM

Well from my understanding, the study was correlational not experimental in design, so they compared groups who ate predominately red meat and groups who ate red meat and other protein sources, and found a statistically-significant decrease in their mortality rates. However the covariables listed with the high-red-meat-consumers (what I find to be potential confonds) were not listed with the moderate-red-meat-eaters, making the findings more questionable to me, I think.

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1528 · March 13, 2012 at 1:18 AM

Well, too much iron can be inflammatory; this is well-known. So that's the iron-heart attack correlation (http://www.cdc.gov/ncbddd/hemochromatosis/pdf/IronOverload.pdf). Still, can't prove nuttin' with this kinds of studies. Smokers tend to eat a lot of meat and drink too much booze - gosh - do you think people who smoke have an unhealthy lifestyle? Like, astonishing! Who knew??????

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4359 · March 13, 2012 at 3:31 AM

It is not well known that dietary iron is inflammatory because it is not true.

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