Vitamin D and COVID: Looking for Magic, Finding Issues

One of the biggest surprises in this COVID-19 pandemic has been intense interest in vitamin D. Earlier this month, readers swarmed around an item we wrote about it. Now, a month later, the interest persists. Some people seem to be looking for magic for COVID from vitamin D. Others are finding issues. We advise sensible caution.

An Expression of Concern

The latest twist in this tale is an “expression of concern” from PLOS ONE about an article the journal had published. In that article, authors proclaimed that adequate vitamin D could reduce the risk of bad outcomes in COVID patients.

However, their study was merely observational. True enough, the authors observed a reduced risk. But they didn’t produce evidence that vitamin D caused that reduced risk. Correlation versus causality rears its ugly head again.

Gideon Meyerowitz-Katz wrote a thorough critique on Twitter, concluding that the study results were “wildly unimpressive.”

On top of all that, PLOS found an issue of undisclosed competing interests. Thus the article now has a big red box on top of it listing all these concerns. The journal is “following up on this case with high priority in light of the public health implications of the article’s results.”

Now Another Study

Despite this kerfuffle, vitamin D keeps coming at us. In the Journal of Clinical Endocrinology and Metabolism this week, José Hernández et al published another observational study of vitamin D and COVID patients this week. It was a small and interesting case-control study of 216 patients hospitalized with COVID-19. The authors matched them to 197 population-based controls.

In their analysis, Hernández et al found lower vitamin D levels in the hospitalized COVID patients, compared to the control group. But in the COVID group, they found no relationship between disease severity and vitamin D – either serum concentrations or supplementation.

Forget the Magic

In the Hernández paper, we find a very sensible conclusion:

“Probably, the best approach should be to identify and treat vitamin D deficiency, especially in high-risk individuals.”

Meanwhile, we’ll need good randomized controlled trials to better define the value of vitamin D for dealing with future waves of this virus. Not magic. Just good clinical science.

Click here for the paper in PLOS ONE, complete with the expression of concern, and here for the Hernández paper. For the critique by Meyerowitz-Katz, click here. Also, Retraction Watch has an excellent write-up on the PLOS kerfuffle here. Finally, Perry Wilson does a fine job here, reviewing a long history of false hopes for magic from vitamin D.

The Magic Circle, painting by John William Waterhouse / WikiArt

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October 30, 2020

10 Responses to “Vitamin D and COVID: Looking for Magic, Finding Issues”

  1. October 30, 2020 at 7:20 am, Nigel Hinchliffe said:

    There has been a pilot RCT in Spain in which hospitalised Covid patients administered with oral Vit D had reduced severity of disease – Entrenas Castillo et al.

    • October 30, 2020 at 9:54 am, Ted said:

      Indeed. I wrote about it here. As the authors of this study say, “larger trials with groups properly matched will be required to show a definitive answer.”

  2. October 30, 2020 at 11:03 pm, Susan said:

    A word of caution, I took vitamin D supplements as suggested by my chiropractor. I am not vitamin D deficient. After about 1 month of taking the supplement, I became anxious, agitated, and nauseous. Please only take under a physician’s direction. Vitamin D supplements are fat soluble and build up in your system.

  3. October 30, 2020 at 11:24 pm, Jo Crowley said:

    I grew up with constant respiratory infections, I could get the flu 3 times in 1 season. I was diagnosed with Vitamin D Deficiency (severe) a couple of years ago. Ever since I haven’t had a single cold, flu or sinus infection. I did get bronchitis for 6 months, but I had my dosage of Vitamin D lowered and skipped my flu shot. Back on track.

  4. October 31, 2020 at 12:16 am, Diana Lee said:

    If a person is low on Vitamin D, taking it just before or while they have COVID probably won’t show any result in making the virus less strong in their system. Low Vitamin D levels take awhile to build back up in a person’s system. I would imagine one would already have had to be taking the Vitamin for a period of time before they acquired the virus to have good results. JMO.

  5. October 31, 2020 at 7:46 am, Ursula C Thime said:

    Medicare offers one wellness visit to our Primary Dr.
    Older people in my circle are many times low on vitamin D.
    As myself.
    My Dr took the time to advise about the benefits of vitamin D Common sense cures more than running after a panacea.

  6. October 31, 2020 at 11:40 am, Naomi Nunez said:

    I have been taking vitamin D now for about a month..Vitamin D. 1000 mgs. is it safe. Im 65 years old with secondaries issues. Im a diabetic..high blood pressue. High cholesteral and C. O. P. it safe for me to take Vitamin D…my doctor gives me Vitamin 12 shots monthly and I do take a daily vitamin

    • October 31, 2020 at 2:34 pm, Ted said:

      For medical advice, Naomi, your doctor is definitely the best source.

  7. October 31, 2020 at 6:53 pm, Shaunn said:

    I am on D-3 supplements prescribed by my pain physician. Must take quarterly blood tests.

    By all means have your doctors test you! I am doing much better with my arthritis because of the D-3.

    Just don’t prescribe for yourself! I have lost dear ones who poisoned themselves from OTC supplements their physicians were unaware of. Don’t mess with body chemistry. Everyone processes nutrients differently.

  8. November 02, 2020 at 6:53 am, Mary-Jo said:

    Vit D is a fat-soluble vitamin which can be stored, potentially toxic if MEGAdoses, therapeutic doses of supplements are NOT needed. So, because it seems to be getting a lot of attention recently, it is not advisable for people to go out and get large dose supplements and take them WITHOUT first having a blood test for vitamin D levels. Labs defer, but generally 30-80 ng/mL, even 25-50 ng/mL should enable good function for an optimal immune system and its role in bone formation and strengthening, and for children, growth and development, especially of bones and teeth. B/c I worked many years with hospitalized patients, mainly as a pediatric RD, vit D was always something I had MDs check for my patients as institutionalized people (indoors a lot) and people living in darker climates are most at risk for deficiency, as well as people with obesity, renal disease, liver dysfunction. But, ALWAYS first check blood levels, and depending on that, supplement, accordingly. I take 25 micrograms daily b/c I live in a northern country