Below is a research summary circulated on a mailing list for medical practitioners. It arrived under the heading: "Red meat is bad for you —and bad for everyone else". Further below is the journal abstract (summary) concerned -- from a very respectable medical journal. The whole thing is, however, one big confidence trick and will achieve nothing other than frightening people off perfectly harmless food that they would otherwise enjoy. The entire report is a scientific, statistical and ethical nothing. Let me tell you very quickly why.
For a start, the "hazard ratios" (relative risks) reported are negligible -- at 1.2, 1.3 etc. The Federal Reference Manual on Scientific Evidence, Second Edition says (p. 384): "the threshold for concluding that an agent was more likely than not the cause of an individual's disease is a relative risk greater than 2.0."
OK. So who cares about a silly old Federal Reference Manual on Scientific Evidence? But it gets worse. The findings are reported in terms of upper and lower quintiles. In other words they threw away three fifths of the information that they had in order to arrive at their reported conclusions. That is quite simply dishonest and unethical. NO categorization of such data for analytical purposes is now ethically defensible. In pre-computer days, when all calculations had to be performed by hand, doing so could in some cases be justified but with the advent of computers there is NO reason why regression techniques that include ALL the data cannot be used. I note that before I had access to computers, I analysed the data from my first ever piece of research (in 1966) using a regressional technique. Even at that early stage I did not contemplate throwing away any of my data in the course of analysing it.
Had the whole of the data been analysed using a regressional technique, there is no doubt the the resultant correlation between meat consumption and disease would have been derisorily small and maybe even of negative sign, indicating that red meat eating is NOT a cause of cancer, heart disease etc. It is certainly not "bad for you —and bad for everyone else". The authors would of course be aware of that but have nonetheless chosen to present their data in a way that makes mountains out of pimples, which seems to me quite simply unethical.
So how did such a piece of utter crap get published in a medical journal? More particularly, why is such crap ROUTINELY published in medical journals? I am afraid that it is a sad outcome of the "publish or perish" regime that prevails in academe. Researchers need to get papers published in order to be promoted. So a well-meaning consensus has emerged among journal editors that they will accept extreme quintile reports out of solidarity with their colleagues. Otherwise they would have to reject more than half of what they currently publish. That the practice routinely results in the public being deceived is of no account. It is an utter disgrace but I doubt if I will live to see it stopped. An ethical vacuum prevails where the public would normally expect the highest ethical standards.
The emailed circular from DocAlert Messages below:
Further evidence of a link between red meat and poor health has emerged from a large cohort of older US adults. Men and women in the top fifth of red meat intake had a significantly higher risk of death over 10 years than men and women in the bottom fifth (hazard ratio for men 1.31, 95% CI 1.27 to 1.35; for women 1.36, 1.30 to 1.43). The authors also found a link between death and a high intake of processed meat such as bacon, ham, and sausage.
The 545 653 adults were between 50 and 71 when they filled in a detailed food frequency questionnaire in 1995. By 2005, more than 71 000 had died. These large numbers mean the authors were able to estimate with some precision the risks associated with eating red and processed meats for both men and women. The analyses were fully adjusted for other lifestyle factors likely to influence lifespan, especially smoking.
These data add to other observational studies that suggest we should all eat less red and processed meats. Not least because the increasing consumption of meat in many countries is putting a strain on global supplies of water, energy, and food in general, says a linked comment (p 543). It is costlier in all these precious resources to grow meat to eat than to grow vegetables and grains instead.
Journal abstract below:
Meat Intake and Mortality: A Prospective Study of Over Half a Million People
By Rashmi Sinha et al.
Background: High intakes of red or processed meat may increase the risk of mortality. Our objective was to determine the relations of red, white, and processed meat intakes to risk for total and cause-specific mortality.
Methods: The study population included the National Institutes of Health–AARP (formerly known as the American Association of Retired Persons) Diet and Health Study cohort of half a million people aged 50 to 71 years at baseline. Meat intake was estimated from a food frequency questionnaire administered at baseline. Cox proportional hazards regression models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) within quintiles of meat intake. The covariates included in the models were age, education, marital status, family history of cancer (yes/no) (cancer mortality only), race, body mass index, 31-level smoking history, physical activity, energy intake, alcohol intake, vitamin supplement use, fruit consumption, vegetable consumption, and menopausal hormone therapy among women. Main outcome measures included total mortality and deaths due to cancer, cardiovascular disease, injuries and sudden deaths, and all other causes.
Results: There were 47 976 male deaths and 23 276 female deaths during 10 years of follow-up. Men and women in the highest vs lowest quintile of red (HR, 1.31 [95% CI, 1.27-1.35], and HR, 1.36 [95% CI, 1.30-1.43], respectively) and processed meat (HR, 1.16 [95% CI, 1.12-1.20], and HR, 1.25 [95% CI, 1.20-1.31], respectively) intakes had elevated risks for overall mortality. Regarding cause-specific mortality, men and women had elevated risks for cancer mortality for red (HR, 1.22 [95% CI, 1.16-1.29], and HR, 1.20 [95% CI, 1.12-1.30], respectively) and processed meat (HR, 1.12 [95% CI, 1.06-1.19], and HR, 1.11 [95% CI 1.04-1.19], respectively) intakes. Furthermore, cardiovascular disease risk was elevated for men and women in the highest quintile of red (HR, 1.27 [95% CI, 1.20-1.35], and HR, 1.50 [95% CI, 1.37-1.65], respectively) and processed meat (HR, 1.09 [95% CI, 1.03-1.15], and HR, 1.38 [95% CI, 1.26-1.51], respectively) intakes. When comparing the highest with the lowest quintile of white meat intake, there was an inverse association for total mortality and cancer mortality, as well as all other deaths for both men and women.
Conclusion: Red and processed meat intakes were associated with modest increases in total mortality, cancer mortality, and cardiovascular disease mortality.
Arch Intern Med (2009) Vol. 169 No. 6. 562-571
In addition to the statistical and ethical failures that I have detailed above, there are of course other large problems with the interpretation of the study. The first or second thing you learn in Statistics 101 is that "correlation is not causation". The authors above were cautious NOT to make causative inferences from their data but that message got lost downstream. Even well-informed people reading the report DID assume a causative relationship. They assumed that red meat eating CAUSED heart disease etc. But NO epidemiological study enables causative inferences. There could easily be third or fourth factors producing the observed association.
Just to give a top-of-the head example of how that could have played out: Given the weak associations reported, maybe a substantial proportion of those who ate little or no meat were Seventh Day Adventists. Adventists are an exceptionally healthy group who encourage vegetarianism. So WHY are they exceptionally healthy? Nobody really knows but it seems likely that the strong social and psychological support that they get from their heavy church involvement reduces stress and thus also reduces stress-related disease. And heart disease is partly a stress-related disease. So even if we accept as proper the statistical jiggery pokery reported above we may be basing our conclusions entirely on the doings of Seventh Day Adventists -- which is not of much relevance to the rest of society.
Posted by John Ray. For a daily critique of Leftist activities, see DISSECTING LEFTISM. To keep up with attacks on free speech see TONGUE-TIED. Also, don't forget your daily roundup of pro-environment but anti-Greenie news and commentary at GREENIE WATCH . Email me (John Ray) here
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