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Issue #73 (November 2020)

From the Editor

As the days grow shorter and colder in the Northern Hemisphere, we’ve decided to cover a handful of seasonally relevant studies in this issue of NERD. One examines how useful honey is for symptoms of upper respiratory tract infection. (Short answer: maaaayybe, kind of?) Two others that I want to focus on here involve the sunshine vitamin: vitamin D.

Vitamin D’s effects are wide-ranging, given the ubiquity of the vitamin D receptor throughout the body. But just because vitamin D is essential doesn’t necessarily mean that supplementing it is useful for everyone. Indeed, many trials looking at the effects of vitamin D supplementation haven’t yielded very promising results. There are a few exceptions, though. One signal that’s been popping out through the noise has been vitamin D’s effect on cancer mortality.

While the current evidence doesn’t strongly support the idea that vitamin D supplementation can prevent getting cancer in the general population, there’s been growing evidence that supplementation can reduce the risk of dying from cancer. We covered this topic in NERD last year by looking at a meta-analysis examining cancer risk and mortality in general. In this issue of NERD, we narrow the focus a bit and review a meta-analysis specifically about vitamin D supplementation’s effect on colorectal cancer. The results are promising: supplementation seems to lower the risk of dying from colorectal cancer in those who already have cancer, with the data hinting at (but not strongly suggesting) a dose-response effect.

Couple this analysis with a hot-off-the-presses secondary analysis of the VITAL trial suggesting that vitamin D supplementation can reduce the risk of advanced cancer, and we’re starting to see the outlines of a possible mechanism emerging: vitamin D supplementation could reduce the risk of dying from cancer by reducing the risk of advanced, more deadly cancer. This hypothesis is far from certain, but given how big of a deal cancer is, I find these findings to be among some of the more exciting ones in the world of supplement research. I’ll be keeping an eye on how things go.

We also cover another vitamin D study in this issue that looks quite promising on its face: the effect of vitamin D supplementation on one of the most common types of vertigo. But while the effect was significant and the study was both large and had a pretty long duration, there are enough problems with the study that makes me doubt how reliable the reported results are. Read on to see if you agree with my take!

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

See other articles in Issue #73 (November 2020) of Study Deep Dives.