Researchers in Spain have discovered that 82% of hospitalized patients with Covid-19 were vitamin D deficient in a new study published today. They studied vitamin D levels in 216 patients admitted to the hospital for Covid-19 treatment in March this year, finding that 8 in 10 patients were considered clinically deficient.
The work published today in The Journal of Clinical Endocrinology & Metabolism also looked at a control group of 197 people who lived in the same geographical area and were similar to the Covid-19 patient group in age and sex. Among these people, 47% were vitamin D deficient.
However, it is important to point out that the conclusions of this study are correlative, not causative – meaning that it can’t be concluded that vitamin D deficiency was directly responsible for a higher chance of being hospitalized with Covid-19. There is however other evidence suggesting that vitamin D might be beneficial in protecting hospitalized individuals from adverse outcomes.
Vitamin D is essential for bone health, but is also thought to have beneficial effects on the immune system too with some evidence that having sufficient vitamin D may give some protection against respiratory tract infections.
Vitamin D deficiency is common, with one study from 2011 estimating that 41.6% of U.S. adults are deficient. However, this number varies greatly depending on race with 82.1% of Black Americans being deficient and 69.2% of Hispanic Americans. Vitamin D can be produced naturally by exposure to sunlight and found in some foods, including oily fish, eggs and fortified milk and plant-based milk substitutes.
Last month, a study from researchers in Boston found that patients over 40 were over 50% less likely to die from the infection if they had sufficient levels of vitamin D. However, the more recent study from Spain wasn’t able to conclude any link between vitamin D deficiency and severity of disease. So the information regarding any benefit of vitamin D for Covid-19 is still a bit inconclusive.
In certain parts of the world, especially where sunlight hours are limited during winter, vitamin D supplementation is routinely recommended by physicians. So, should everyone start taking vitamin D now even if it isn’t clear whether it might help with Covid-19? Well, not necessarily. It is important to note that too much vitamin D can be toxic and it can also interact with certain medications. So, if in any doubt, check with your doctor about whether it is recommended and safe to take vitamin D supplements.