Nutrition Science and Everyday Application - beta v 0.1

TYPES OF RESEARCH STUDIES AND HOW TO INTERPRET THEM 93
the drinks, but the athlete believed that the Super Duper Sports Drink was going to help him
run faster, so he did. This improvement is due to the placebo effect. Ironically, a study similar
to this example was published in 2015, demonstrating the power of the placebo effect on
athletic performance. 3
Figure 2.4. An example of the placebo effect
Blinding is a technique to prevent bias in intervention studies. In a study without blinding,
the subject and the researchers both know what treatment the subject is receiving. This can
lead to bias if the subject or researcher have expectations about the treatment working, so
these types of trials are used less frequently. It’s best if a study is double-blind, meaning that
neither the researcher nor the subject know what treatment the subject is receiving.
It’s relatively simple to double-blind a study where subjects are receiving a placebo or
treatment pill, because they could be formulated to look and taste the same. In a single-
blind study, either the researcher or the subject knows what treatment they’re receiving, but
not both. Studies of diets—such as the Mediterranean diet example—often can’t be doubleblinded
because the study subjects know whether or not they’re eating a lot of olive oil and
nuts. However, the researchers who are checking participants’ blood pressure or evaluating
their medical records could be blinded to their treatment group, reducing the chance of bias.
Like all studies, RCTs and other intervention studies do have some limitations. They can be
difficult to carry on for long periods of time and require that participants remain compliant
with the intervention. They’re also costly and often have smaller sample sizes. Furthermore,
it is unethical to study certain interventions. (An example of an unethical intervention would
be to advise one group of pregnant mothers to drink alcohol to determine its effects
on pregnancy outcomes, because we know that alcohol consumption during pregnancy
damages the developing fetus.)