More study needed on vitamin D, COVID-19
A simple vitamin could prove helpful in the fight against COVID-19, one Instagram post claims.
“Vitamin D insufficiency- an easily correctable indicator of metabolic dysfunction-may account for the majority of COVID-19 deaths and yet the mainstream messaging remains fear-based and hysteria promoting. Surprised?” reads a Nov. 30 tweet written by Paul Saladino, M.D., and shared on his Instagram page, a post that has been deleted.
A screenshot of the alleged study, “Vitamin D Insufficiency May Account for Almost Nine of Ten COVID-19 Deaths,” is provided at the end of the tweet.
In his Instagram post, Saladino – a San Diegobased psychiatrist and advocate of the restrictive meat-based “Carnivore” diet – acknowledged that anyone reading the study may infer vitamin D supplementation “is all that is needed to improve COVID outcomes.” He expresses skepticism at the thought, but also recommended that individuals worried about the virus “optimize BOTH their 25-OH D levels (above 30ng/ml at least) and their metabolic health,” the latter through his prescribed diet.
In an email to USA TODAY, Saladino said that neither his post, nor his other Instagram content, should be considered medical advice.
What is vitamin D?
Vitamin D is among the small number of vitamins that are fat-soluble and important for growth, reproduction and overall health. The vitamin, also known as “calciferol,” helps with intestinal calcium absorption, ensuring bone health, as well as maintaining adequate levels of phosphorous, a mineral assisting in muscle contraction and nerve signaling, among many other crucial physiological functions.
Deficiencies in vitamin D typically lead to osteoporosis, muscle weakness, multiple sclerosis and possibly diseases like cancer, diabetes and cardiovascular disease. Numerous studies also suggest vitamin D may play a role in immune function, autoimmune diseases like rheumatoid arthritis, and infectious disease.
What does the study say?
What Saladino cites in his tweet is a comment to an observational study published in the journal Nutrients in September.
The original study by a University of Heidelberg, Germany, research group looked at vitamin D status among 185 patients diagnosed with COVID-19 and treated at the university’s hospital. The group also looked at levels of interleukin 6, a molecule with diverse physiological functions, one of which is regulating the body’s inflammatory response to infection.
The study observed that vitamin D-deficient patients had a “higher hospitalized rate and required more (intensive) oxygen therapy and (invasive mechanical ventilation).” Vitamin D deficiency appeared to be associated with a “6-fold higher hazard of severe disease” and an “~15-fold higher risk of death,” when adjusted for age, gender and comorbidities.
A comment on the study, from Drs. Hermann Brenner and Ben Schöttker of Heidelberg’s Division of Clinical Epidemiology and Ageing Research, translated the study’s findings to a larger scale.
“These results imply that 87% of COVID-19 deaths may be statistically attributed to vitamin D deficiency and could potentially be avoided by eliminating vitamin D insufficiency,” they wrote in November.
In a follow-up, Drs. Aleksandar Radujkovic and Uta Merle advised the findings should be extrapolated carefully. “As already pointed out and discussed, the results of observational studies always need to be interpreted with caution, since they are vulnerable to bias and unknown confounders,” they write.
It is worth noting that a November randomized controlled trial out of the University of São Paulo in Brazil – yet to be peer-reviewed – found vitamin D supplementation did not appear to improve outcomes for patients hospitalized with severe COVID-19.
Vitamin D generally safe, but caution advised
Vitamin D deficiency is prevalent across the world and is emerging as a more common condition.
While it is easily treated with supplementation – considered generally safe – too much vitamin D can lead to toxicity, known as hypervitaminosis D. Symptoms of toxicity include a range of gastrointestinal symptoms such as nausea, vomiting, stomach pain or diarrhea. Excessive vitamin D intake can result in kidney injury and bone loss.
Our ruling: Missing context
We rate this claim MISSING CONTEXT because without additional context it might be misleading. A University of Heidelberg study did find vitamin D deficiency associated with increased COVID-19 mortality, even when adjusted for age, gender and comorbidities. However, as the researchers themselves note, a limitation to the study is it being observational; it proves association but not causation. Inferring the benefit of vitamin D supplementation should be regarded cautiously until more studies, particularly randomized controlled trials, are done. Unsupervised and/or excessive vitamin D intake can lead to toxicity.