Dr. Lee, the Healthy Professor

Review of Harvard Red Meat and Increased Mortality Study

Written by L. Lee Coyne | Views 3963

Harvard School of Public Health suggests that a steady diet of red meat increases the odds of dying prematurely.

A report in Harvard Health Publications on March 12 2012 from the Harvard School of Public Health suggests that a steady diet of red meat increases the odds of dying prematurely. The Study urges moderation in red meat intake.

The study linking red meat and mortality lit up the media in more ways than one. Hundreds of media outlets carried reports about the study. Headline writers had a field day, with entries like “Red meat death study,” “Will red meat kill you?” and “Singing the blues about red meat.”

The warning from the study, done by researchers at the Harvard School of Public Health, sounded ominous. Every extra daily serving of unprocessed red meat (steak, hamburger, pork, etc.) increased the risk of dying prematurely by 13%. Processed red meat (hot dogs, sausage, bacon, and the like) upped the risk by 20%. The results were published in The Archives of Internal Medicine.

I did respond to this item when it hit my Facebook page and was going to leave it at that. However I have received too many questions about the report to just let it pass.
Here is:
a. my facebook response
b. a few highlights featuring my critical review of the study, and
c. links to several blogs that have reviewed this topic far more extensively than I.

My quick response and exchange on facebook:

L. Lee Coyne: Another epidemiological study declaring "guilt by association" no suggested mechanisms for why meat might cause cancer or any other ailments responsible for premature death. Too many uncontrolled variables in the study - like methods of preparation, sources of the meat (organic?), condiments, characteristics of the participants or other dietary components. March 14 at 3:38pm

John Barendrecht wrote: So red meat kills Americans but not Japanese? March 14 at 4:36pm.

I was a little distress by the following comment by Joe McCleery of England (I think) - I believe he is a Harvard Graduate

Joe McCleery: Dear Lee and John, did you read the article? It clearly states: "Because this was the largest, longest study to date on the connection between eating red meat and survival, the findings are worth paying attention to. But they aren’t the last word on the topic, and the numbers need to be put into perspective."March 14 at 4:43pm.

His comment and the Harvard Health letter comments about "largest and longest study" is puzzling. Large and long does not make it a good study particularly if the design is faulty and if you realize the study was not designed to test this hypothesis. In fact the study was not designed to test any hypothesis - it was and is merely a data gathering fest.

My response was:
L. Lee Coyne: Yes I read the study and it does not deserve the widespread scare tactic attention it has received. ".. increased risk from red meat MAY come from the saturated fat, cholesterol, and iron it delivers." - not very scientific and wrought with some outdated assumptions. "...cooking red meat at high temperature COULD also contribute."- another definitive scientific statement...." ... Cutting back on meat can also help the health of the planet." open for serious debate-- how does shipping fresh produce all over the world help the planet? Comparing meat to pasta is a meaningless nutrition discussion. March 14 at 5:07pm.

And even Dr. Skerrett partially agreed with me

Harvard Health Publications Lee -- I agree that the study didn't warrant the "scare tactic attention" it got. That's why I tried to put the risk numbers in perspective. But the evidence is trending toward the health hazards of too much red meat in the diet. PJ Skerrett (Senior editor, Harvard Health) March 15 at 3:58am ·

Joe McCleery While I can understand your frustration with the limitations of science in the context of practical and ethical constraints (e.g., inability to randomly assign people to different eating patterns), and especially your frustration with media presentations on health research, I can not understand your anger seemingly directed at scientists who are doing the best they can to further our understanding of healthy eating and living habits, Lee. Take it for what it is, and get over it.

My response again to Dr. McCleery was that the scientists responsible are tending to extrapolate the significance of the data by suggesting without supporting evidence a plant based diet. That is misleading and counter productive and I will not merely "get over it".

Highlights of my critique.
1. A month ago, a Japanese study of more than 51,000 men and women followed for 16 years found no connection between moderate meat consumption (up to three ounces a day) and premature death. Last year, a study by different researchers from the Harvard School of Public Health found no connection between eating unprocessed red meat and the development of heart disease and diabetes, though there was a strong connection with eating processed red meat.
2. The study was a Red meat and mortality -- that means deaths from all causes. The Abstract used the phrase "documented 23 926 deaths (including 5910 CVD and 9464 cancer deaths). That means there were 8,552 deaths from causes other than heart disease and cancer.
3. Even the authors stated "its relationship with mortality remains uncertain."
4. This is an epidemiological study also known as Observational studies – or prospective or cohort studies. For a great critique of these studies I defer you to a great blog on the subject by Dr. Michael Eades (author of the book Protein Power). Observational studies are useful tools for scientists to create hypotheses that need to be tested with appropriate clinical and experimental studies. We should never make decisions based exclusively on data collection and suppositions.
5. Fundamental to the results is the fact that Correlation does not mean Causation.
6. The study was not actually a study - they picked the data out of two studies a. the Health Professionals Follow-up Study (1986-2008) (abbreviated to HPFS) involving 49,934 men and the Nurses’ Health Study (1980-2008) (abbreviated to NHS) involving 92,468 women. After excluding people with cardiovascular disease (CVD) or cancer at the start of the study and excluding people whose dietary responses were incomplete, this article proceeded to review data from 37,698 men in the HPFS and 83,644 women in the NHS. Diet was assessed by validated food frequency questionnaires and updated every 4 years.
7. Food frequency questionnaires have a checkered and often questioned history.
8. The numbers indicating difference in mortality rate are very small. So small, I doubt they could be declared significant.
9. There is also a potential conflict of interest issue as one of the authors Dr. Walter Willett is a known vegetarian who speaks at vegetarian conferences. Also one of the "peer" reviewers was Dr. Dean Ornish, a high profile proponent of vegetarian eating.

There are several outstanding critiques of this study by some very qualified people so I am going to defer to their reviews.
Please read them they are comprehensive and illuminating.

Dr. Jonny Bowden Denis Minger Gary Taubes Zoe Harcombe


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