This study is widely cited as the bedrock evidence that a vegetarian diet is superior to one with meat.
The Seventh-day Adventist study
These and other arguments against eating red meat dovetailed with Ancel Keys’s advice about cutting back on saturated fat and made his recommended diet seem that much more intuitive to a nation of responsible consumers. The result has been that since the 1970s, a bias against red meat has settled in, even in the scientific research community, and this bias can be seen in the way that experiments are performed and interpreted.
One of the more stark examples of prejudice in the field is the most famous study of vegetarians ever performed, involving 34,000 Seventh-day Adventist men and women who were followed by researchers throughout the 1960s and seventies. The Seventh-day Adventist Church prescribes a vegetarian diet that allows eggs and dairy but little meat or fish, and in 1978, investigators reported that the Seventh-day Adventist men on this diet had lower rates of all kinds of cancer (except prostate cancer, which was higher) than non-Adventist men, as well as fewer deaths from heart disease. Women, by contrast, saw no benefitV and an increased risk for endometrial cancer—in one of many examples of a contrary result on women that has gone unpublicized.
This study is widely cited as the bedrock evidence that a vegetarian diet is superior to one with meat. Yet again, it’s easy to see many problems with the study that make the findings less than reliable. For example, one cohort of the Seventh-day Adventist subjects were compared to a control group living at the opposite end of the country, in Connecticut, where environmental factors could not be assumed to be similar (indeed, coronary mortality was 38 percent higher on the East Coast than in the West, and this variance alone could have explained the different rates of heart disease observed). More important, however, was the fact that the Adventist men following the church’s vegetarian teachings were also very likely to be following other Seventh-day Adventist advice as well. They would probably have refrained from smoking and participated in the church’s social and religious community. They were also known to be better educated than the control group. All these variables are associated with better health and therefore make it impossible to say how much diet alone affected outcomes. (Moreover, the diet itself was assessed only once in twenty years, and then only for those subjects who chose to return a questionnaire, which creates a distortion, because people who participate tend to be healthier than those who can’t or don’t.)VI Even the study director acknowledged these problems.VII Finally, one glaring bias not mentioned in any of the papers on the study is that Loma Linda University, home of the Seventh-day Adventist study, is an institution run for and by Seventh-day Adventists.
The Seventh-day Adventist study, despite its obvious flaws, was one of the foundational pieces of evidence used as “proof” for the belief that red meat is unhealthy.