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Issue #59 (September 2019)

From the Editor

Volume 1

NERD has undergone a few changes over the course of its almost five-year lifespan. And over the course of the next several months, we’ll be slowly phasing in a few more.

Since we’re all about the evidence at Examine.com, we’ve spent several months polling and interviewing NERD subscribers to learn more about what you’d like out of NERD so we can cater to your needs. One of the main takeaways we heard is that, while most of you appreciate NERD’s rigor, sometimes it can be hard to keep up with the deep-dive reviews.

Over the next few months, we’ll be rolling out some changes to make NERD easier to use, consume, and understand. In this volume, we’re taking the first step toward helping you keep up and get something out of each article by introducing a new section to our deep-dive articles called “Quick takes”.

The goal of this section is to give you a very quick overview of the study and its main takeaways in an easy-to-read bulleted list. We put it right at the start of each article so you can get an idea of what the study’s about before reading the full review. We hope this will help you retain more information if you read the full review, and at least get the gist of what the study says if you don’t.

We’ll still be keeping our older summary section, “What should I know?”, at the end of each review, since these two summaries serve different functions. The “What should I know?” section is more narrative and has more information than “Quick takes” does. Also, since it’s at the end of the review, it’s more useful for reinforcing what you took in while reading the full review.

On the other hand, “Quick takes” is right up front and allows you to get the basics of the article without having to scroll through the deep-dive review in order to get to the summary. I also suspect that sandwiching each deep-dive review with two different types of summaries will help readers who consume the full review digest the article’s contents a little better.

We’ve also standardized each “Quick takes” section so that they’ll be easy to compare and you’ll know what information to expect from each quick take.

The format of the section isn’t set in stone, though. So if you have any suggestions for improvement, let us know! You can always send us feedback through either our contact page or let us know on the private NERD Facebook forum.

Keep an eye out for more changes in the months ahead!

Gregory Lopez, MA, PharmD
Editor-in-chief, Nutrition Examination Research Digest


Volume 2

Over the past few months, I’ve chatted a bit about supplement safety. I’ve noted that we don’t tend to cover much research about supplement safety in our deep dives, not because supplement safety’s not important, but because there’s little high quality research in the form of randomized controlled trials that focuses on safety. Since NERD deep dives tend to focus on the kind of research that’s most reliable when it comes to establishing causality, and randomized controlled trials are the best way to infer causality, we tend not to cover the topic much there.

This volume is an exception, though: we actually get to cover a randomized control trial that may have some safety implications, to both our surprise as well as the surprise of the researchers who conducted the study.

The researchers set out to examine how escalating doses of vitamin D supplementation affected bone strength and density over three years in people without osteoporosis, as measured by a method that’s more sensitive than the more commonly-used dual X-ray absorptiometry (DXA). The researchers sensibly hypothesized that increasing doses of vitamin D would lead to increased bone density and strength over time. That’s not what happened, though.

Instead, they found that bone quality tended to decrease over time regardless of whether people were treated with vitamin D or not, and regardless of dose. While this goes against their hypothesis, it’s not completely unexpected; there’s recent evidence[1][2] to suggest that vitamin D supplementation may not be helpful for bone health except in cases of vitamin D deficiency. The people in the study we cover in this volume were not vitamin D deficient, though, so the lack of an effect isn’t terribly shocking.

What’s more surprising is that the authors actually saw a negative dose-response relationship between vitamin D and bone mineral density. In other words, it appeared that the bone quality of people who took higher doses of vitamin D actually worsened over the course of the study.

The usual caveats about population should be kept in mind when thinking about these results. However, there’s a more interesting caveat that the authors of the study mention that I’d like to emphasize. They clearly state that these results need to be replicated before saying with any certainty that increasing vitamin D dose actually harms bone mineral density in this population.

The reason the authors give for this is interesting: it’s because the study actually went in the opposite direction of their hypothesis. In other words, it was surprising. While the study at hand is evidence in favor of the hypothesis that higher vitamin D dosing could negatively impact bone density, when you get evidence that goes against somewhat strong expectations, it’s good practice to repeat the experiment. That’s because properly taking evidence into account should nudge beliefs in one direction or another, but needn’t change your mind wholesale.

In other words, it’s not a problem to acknowledge evidence for something you don’t yet believe, especially when the results are surprising.

Gregory Lopez, MA, PharmD
Editor-in-chief, Nutrition Examination Research Digest

See other articles in Issue #59 (September 2019) of Study Deep Dives.