The Magic Lantern

Magical Measures from BMJ to Prevent COVID-19

Call us quaint. But we believe medical journals should publish research grounded in facts and evidence. Not speculation. Especially in the midst of a pandemic that has taken the lives of more than three million people around the world. BMJ, though, has a different approach. This week the BMJ group has a paper promoting magical measures to prevent COVID-19. In BMJ Nutrition, Prevention & Health, the following headline appeared:

Modest effects of dietary supplements during the COVID-19 pandemic:
insights from 445 850 users of the COVID-19 Symptom Study app

The sensationalism worked, even if the study didn’t match the headline. This publication of dubious value placed in the top five percent of all research outputs scored by Altimetric. That score means the publication got a lot of traction in news and social media.

A Meaningless Correlation

Let’s start with what these researchers actually found. They fished through data from nearly half a million users of an app they’re selling for wellness. They offer no documentation of a pre-specified protocol for this analysis. If they had one, they did not specify it in their paper or publish it.

Researchers compared self-reported results of COVID-19 tests to self-reports of dietary supplement use. They hunted for correlations. For vitamin C, garlic, and zinc they came up empty. They couldn’t find a correlation between a using those supplements and getting a positive test for COVID-19. But they scored on probiotics, omega-3 fatty acids, multivitamins, and vitamin D. They found modestly lower infection risk – in the range of 10 percent – for people taking those supplements.

This finding is meaningless. To begin with, it’s a small difference. Such a small difference pales in comparison to the prevention effect of things that really work. Masks cut the risk by 65 percent. Social distance can reduce risk by 75 percent. Vaccines are up to 95 percent effective in preventing infections.

On top of that is the problem of confounding. The authors of this study adjusted their analysis for age, sex, BMI, and health status. But they did not have data on behaviors like social distancing, hand washing, or sanitizing. They had incomplete data on mask wearing.

So bottom line, a 10 percent difference in the risk of infection for people who conscientiously took these supplements might easily be the result in different behaviors among these conscientious individuals.

We grant that you can find much of this disqualifying information by reading the details of this paper. But that does not justify publishing such a misleading topline.

Marketing Gold for Dietary Supplements

This publication is a marketing gold mine for dietary supplements. All over the world, people are having a tough time with measures that actually do reduce infection risks. Vaccine supplies are still too limited for many people. Some people are afraid of the vaccine. Wearing a mask and keeping your distance from other people is a real drag.

So magical measures for preventing COVID-19 are really appealing right now. We are haunted by people saying they have no plans to get a vaccine: “I just say take some vitamins.”

No wonder this dubious paper is a public relations triumph. It is also a triumph of medical misinformation. BMJ should be ashamed for publishing such misleading information.

Click here for the study and here for a thread by epidemiologist Darren Dahly explaining some of the flaws in this paper.

The Magic Lantern, painting by Ferdinand du Puigaudeau / WikiArt

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April 22, 2021