Why the Results of Double-Blind Studies are Suspect*

Double-blind, placebo-controlled studies are widely regarded by the scientific community as the “gold standard” for testing the efficacy of pharmaceuticals. In fact, the effectiveness of a potential medication is not considered to have been adequately demonstrated unless it is so tested. A double-blind study is so-called because neither the subjects nor the experimenters know to whom the actual drug or placebo** has been administered. The reason for this reciprocal concealment is that every scientific study requires a control group, which is treated the same in every respect as the experimental group except for receiving the active principal being tested. To offset the placebo effect, control-group members are given sugar pills, which have insignificant physiological effects. Those receiving the pharmaceutical, however, are likely to experience non-negligible side effects such as dry mouth, dizziness, headache, diarrhea, etc. Therefore, the placebo effect (recoveries arising just from subjects’ perceptions that their ailments are being treated) would be expected to be stronger for those receiving the pharmaceutical, flawing such a study.

For a study to be scientifically valid, the placebo should have all the effects of the pharmaceutical other than the “beneficial” one. Unfortunately, this modification, called balanced placebo design, is seldom used and very difficult or impossible to achieve. .

It would seem that drugs with a lot of side effects are more likely to do well in a double-blind, placebo-controlled study than those with milder side effects and may provide little or no benefit.

*From Robert Chuckrow, The Intelligent Dieter’s Guide, Rising Mist Publications, Briarcliff Manor, NY, 1997.

**A placebo is a pseudo medication, consisting of non-active principle, which, in scientific studies, is administered to a control group of subjects to distinguish the true effects of the active principle, given to another group of subjects, from spurious effects that may arise from spontaneous or psychosomatic recovery (the so-called placebo effect).

©Copyright 1997, 1013 by Robert Chuckrow

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