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Issue #24 (October 2016)

From the Editor

Volume 1

So apparently there’s a presidential election next month. Have you heard about this?

Just kidding. I don’t spend 24 hours a day buried under nutrition research (only 22 or so). When I emerge out of my pile of p-values, and observe comments about the presidential election, there’s always one thing I’m most surprised by. And no, it doesn’t have to do with either candidate.

Everybody has a strong opinion on extremely complex policy issues. All 242 million adults in the US, along with many younger people as well. How is that possible? Does everyone know the secret to peace in the Middle East? And everyone also knows the key to sustainable economic growth while not up-ending the job situation of millions of citizens?

The armchair quarterback has a more insidious relative, the armchair politician. And the armchair politician has a second-cousin as well, the armchair nutritionist.

You see, some issues only have a handful of variables involved. If you want to buy a quality new car, you can peruse online reviews, try out the car for yourself, and ask people you know who are into automobiles. So there aren’t that many (any?) people who proclaim that Geo is the greatest car maker of all time, because the variables all point to the same answer: false.

But for every nutrition and diet related issue, there is someone on both sides, who staunchly opposes any view that conflicts with their own. A large number of people avoid animal products because they’re sure of the unhealthiness of eating meat or drinking milk. Some people are low-carb evangelists, and they’ll tell anyone willing to listen that they’d be healthier if they cut out a large chunk of their carb intake. These strong positions don’t just apply to animal products and carbs though, there are also people with strong positions on either side of GMOs, saturated fat, and pretty much everything else you can imagine.

People who read research all day long tend to not have extremely strong views on any particular issue. And that’s because of three distinct reasons. First, there is decent research on both sides of many controversial issues. Second, research is an ongoing process, given that our whole field is based on the scientific method (which is iterative by nature). Third, “published research” does not equal “fact”. Much of the published literature has important methodological flaws. And due to the controlled nature of research, it won’t ever capture the full spectrum of human effects, especially given the relative lack of funding for certain topics.

I’ll take back the first sentence of the last paragraph. I do have a strong view on nutrition research. And that is this: there are more unknowns than knowns, and anybody who pretends otherwise is automatically suspect.

Kamal Patel,
Editor-in-chief, Nutrition Examination Research Digest

Volume 2

You probably already knew this, but nutrition science is complicated. It doesn’t lend itself to three paragraph clickbait articles very well.

But if you google topics like GMOs or vitamin D, you’ll likely stumble across a few clickbait articles that start with the premise that GMOs are harmful (or not harmful at all), as well as abundant articles of the format “vitamin D is great for bla bla bla condition!”.

While you don’t need a graduate degree in nutrition to understand the basics of nutrition issues, there are a few principles that can greatly, greatly improve the quality of discussion on these topics:

1) “Randomized trial” does not equal “truth”

When some people find out about the magic of pubmed, they use pubmed links like weapons. Oh, you don’t like low-carb diets? PEW PEW PEW! I’ll throw a bunch of study links at you. Unfortunately, that’s not the way that argumentation works. The study is a conduit of knowledge, not knowledge in and of itself. So a link to a study is only a link to potentially relevant knowledge. Or in some cases, potentially irrelevant or misleading knowledge.

For example, studies funded by soda manufacturers are much more likely to show neutral results for sugary or diet drinks. Studies funded by nonprofit entities are more likely to find harm. I highly doubt that the non-profit entities have a secret agenda to destroy any for-profit entity. Using Occam’s razor, the simplest explanation is that the company-funded studies have been designed or reported in such a way as to emphasize the good while de-emphasizing (or even sometimes ignoring!) the bad.

2) Studies don’t exist in a vacuum

Imagine that you’re a researcher who published a couple really cool studies on vitamin D and blood pressure, a few years ago. And suddenly, a study comes out that finds the opposite of what your studies found. It doesn’t matter what the study methods were in your study, compared to their study. Their study is newer, and has at least temporarily relegated your study to the dustbin, in the eyes of the media and public.

So that means reading the full text of a study isn’t enough. You also have to know about other relevant studies, and know how to compare the details of these studies (biostatistics, patient characteristics, etc).

3) You don’t need a study for everything

This cannot be repeated enough. Let’s say that you have a friend who feels crappy whenever they drink lemonade. It doesn’t make any sense, and there’s been no studies … it must be psychosomatic.

Wrong. Humans are so sure of their limited cognitive abilities that they’ll disregard anything that doesn’t fit into their predefined mold. If someone reliably feels crappy whenever they drink lemonade, that’s a very valuable observation, and the starting point for further thought. It’s not something that has to be backed up by a study, because who the heck is going to fund a study on lemonade side effects?

Kamal Patel,
Editor-in-chief, Nutrition Examination Research Digest

See other articles in Issue #24 (October 2016) of Study Deep Dives.