“To D or not to D, that is the question.” — Dr. Victor Sierpina
Vitamin D is an essential regulator of human immune function and is thought to stimulate a human’s natural immune response, providing front-line protection against infectious agents by increasing the expression of the human proteins important in defense against respiratory tract pathogens.
It’s estimated as much as 40 percent of the U.S. population doesn’t get enough vitamin D and as many as 1 billion people worldwide have deficient levels. This could be a result of people spending less time outside in the sunlight, hampering the production of the active form of vitamin D.
There’s no international consensus on how much vitamin D someone should take daily. The Endocrine Society suggests adults should get 400 to 1000 IU daily for adequate intake. Many medical providers recommend from 4,000 IU to 10,000 IU, particularly for those found to be deficient and with certain medical conditions, such as osteoporosis.
In recent years, researchers have begun to study the impact of vitamin D supplements on respiratory infections. This topic has been debated and has yielded mixed results. A recent study from the British Medical Journal, with more than 11,000 participants, revealed, however, that vitamin D supplementation reduced the risk of respiratory disease overall.
More recently, researchers began to assess whether there was a correlation between people contracting the COVID-19 illness and those who are likely to have a vitamin D deficiency. Evidence suggests low vitamin D levels are associated with a higher risk of infection with COVID-19.
One study revealed Black individuals who had higher levels of vitamin D were less likely to test positive for COVID-19 compared to those who were just considered to only have “sufficient levels” of this essential vitamin. Another study of hospitalized patients from Spain who had contracted the COVID-19 illness found that over 80 percent of these hospitalized patients had a vitamin D deficiency.
Although these studies are yielding promising results, it’s important to consider that much of the available evidence only reveals a correlation — not causation between vitamin D deficiency and COVID-19 illness. There also are some studies that have found no association between COVID-19 and vitamin D levels.
Once a patient has contracted COVID-19, the benefit of vitamin D appears to lessen. In conclusion, whether one tests positive for COVID-19 or not, taking vitamin D would be beneficial with a dose of around 2,000 to 4,000 IU daily. In addition, it appears vitamin D is better at helping prevent COVID-19 infections rather than treating them after the onset of illness.