As a follow-up to Monday’s article about scientific studies,
why they are often contradictory and the need to understand how they are
structured to assess their credibility, I came across this excellent example in
my reading file.
Remember the key points from last time:
- Negative results, those that show something doesn’t work or there is no danger, often don’t get a lot of publicity – even if knowing that information could be important;
- Lack of funding for unexciting project leads to reduced efforts by researchers to replicate or validate previous studies;
- When studies are not replicated and validated the strength or their results is questionable, and they are likely to be overturned;
- Small sample sizes are prone to yield weakly supported results;
- Even with a larger sample, a one-time study may produce a statistical fluke rather than a real scientific finding;
- Finally, a lot of charlatans on TV and the Internet describe themselves as scientists and use scientific-sounding jargon to make a sale.
Now comes the example from Business Insider. The headline reads, “Scientists who found
gluten sensitivity evidence have now shown it doesn't exist.” The same people whose small study in 2011 concluded
that “gluten-containing diets can cause gastrointestinal distress in people
without celiac disease,” a condition they called non-celiac gluten sensitivity, went
back to question their own results. In
the follow-up study they tested thirty-seven self-identified gluten-sensitive
patients.
Here’s how it went.
The researchers provided every meal for twelve weeks. The meals cycled through high-gluten,
low-gluten, and no-gluten diets. Without
knowing which diet plan they were on at any given time, the participants reported
pain, bloating, nausea, and gas to a similar degree for each of the diets. The researchers could find “absolutely no
specific response to gluten” and were forced to rethink their original (2011)
conclusions. The participants “expected
to feel worse on the study diets, so they did. They were also likely more
attentive to their intestinal distress, since they had to monitor it for the
study.”
Does that matter to the food industry? – Of course not! As long as 30 percent of people want to eat
less gluten and gluten-free products produce $15 billion in sales, why should
they care? The good news is for the 1
percent who actually has celiac disease.
They don’t have to search so hard for gluten-free food. The other 29 percent with a problem that’s
all in their head puts pressure on the manufacturers to make sure the labels
are big and bold, regardless of the science.
This is the drawback to the labeling argument that regardless
of the science everyone has a right to know what they are eating and should be
able to make an informed choice. If that
informed choice is based on faulty assumptions, superstition and scientific
advice from Facebook friends, it is a drain on society. When resources are spent to satisfy fantasy
fears, they cannot be used to better purposes.
By the way, the example comes from August 2015 showing the truth in the first bullet point above that studies showing no danger get far less publicity.
By the way, the example comes from August 2015 showing the truth in the first bullet point above that studies showing no danger get far less publicity.
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