Diet and the value of “double-blind” study

090916The medical journal, BMJ, recently published a study that examined how diet affects heart health. The Minnesota Coronary Experiment was a “double-blind randomized controlled study” conducted between 1968-73.

When a study is “double blind,” it means both the investigator and the subjects being tested do not know whether the subject is in the test group or the control/placebo group. Double blind randomized studies are considered the most reliable of scientific inquiry methods.

The results of the study flies in the face of current thinking regarding saturated fats and the role they play on heart health.

Some of the study participants were assigned to a control diet that saw them receiving 18.5 percent of their calories from saturated fats and only 3.8 percent from unsaturated fats. The other participants were given an intervention diet that lowered the saturated fat intake to 9.2 percent and the unsaturated fat to 13.2 percent.

The results were unexpected. While the intervention diet patients had a significant drop in their total serum cholesterol compared to the patients on the control diet, the intervention diet patients did not have any decreased risk of death. And in fact, they actually had an increase in mortality rate and especially among those 65 years and older.

The results of this study emphasize the importance of having double-blind studies. This double-blind study was looking to prove that replacing saturated fats with unsaturated fats would reduce coronary heart disease and death by lowering serum cholesterol. Because a random group of people was used and neither the doctors or patients involved were aware of which diet was assigned, the results were profound and the hypothesis was debunked.*

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