Nutrition Science and Everyday Application - beta v 0.1

TYPES OF RESEARCH STUDIES AND HOW TO INTERPRET THEM 95
analysis is a type of systematic review that goes one step further, combining the data from
multiple studies and using statistics to summarize it, as if creating a mega-study from many
smaller studies. 4
However, even systematic reviews and meta-analyses aren’t the final word on scientific
questions. For one thing, they’re only as good as the studies that they include. The Cochrane
Collaboration is an international consortium of researchers who conduct systematic reviews
in order to inform evidence-based healthcare, including nutrition, and their reviews are
among the most well-regarded and rigorous in science. For the most recent Cochrane review
of the Mediterranean diet and cardiovascular disease, two authors independently reviewed
studies published on this question. Based on their inclusion criteria, 30 RCTs with a total
of 12,461 participants were included in the final analysis. However, after evaluating and
combining the data, the authors concluded that “despite the large number of included trials,
there is still uncertainty regarding the effects of a Mediterranean‐style diet on cardiovascular
disease occurrence and risk factors in people both with and without cardiovascular disease
already.” Part of the reason for this uncertainty is that different trials found different results,
and the quality of the studies was low to moderate. Some had problems with their
randomization procedures, for example, and others were judged to have unreliable data.
That doesn’t make them useless, but it adds to the uncertainty about this question, and
uncertainty pushes the field forward towards more and better studies. The Cochrane review
authors noted that they found seven ongoing trials of the Mediterranean diet, so we can
hope that they’ll add more clarity to this question in the future. 5
Science is an ongoing process. It’s often a slow process, and it contains a lot of uncertainty,
but it’s our best method of building knowledge of how the world and human life works. Many
different types of studies can contribute to scientific knowledge. None are perfect—all have
limitations—and a single study is never the final word on a scientific question. Part of what
advances science is that researchers are constantly checking each other’s work, asking how
it can be improved and what new questions it raises.
Self-Check:
An interactive H5P element has been excluded from this version of the text. You can view it online here:
https://openoregon.pressbooks.pub/nutritionscience/?p=971#h5p-32