December 2020



    Studies underway around the world are examining if the ’sunshine vitamin’ is useful in preventing or treating COVID-19.

    Can vitamin D help reduce the risk of catching coronavirus and even aid in treating patients with the virus?  Evidence from studies using vitamin D to prevent or treat COVID isn’t conclusive, but some findings are promising.  Dozens of studies now under way are looking into possible links between vitamin-D deficiency and coronavirus.  One, published in JAMA in September, used data from 489 patients in Chicago.  The data showed the risk of testing positive for the disease was 1.77 times higher for people with a deficiency compared to those with adequate levels of vitamin D.  Medical and nutrition agencies in the U.S., European Union and the U.K. have recommended that adults supplement diets with vitamin D, particularly in the winter.   Recommendations range from 1,000-4,000 IUs per day.  Some vitamin D, although not much, is available in the diet; another natural source is sunlight, but for most locations this is true only in the summer months. 

    Studies like the ones described above suggest low vitamin D levels are associated with a greater risk of catching COVID but they don’t demonstrate that it is the cause of that greater risk.  A pilot study in Spain goes further, suggesting the nutrient may help treat COVID.  There, patients hospitalized with COVID were treated with a high dose of a derivative of vitamin D that is easily absorbed through the gut.  Of 50 patients who received vitamin D, two entered intensive care and none died.  Of 26 in the control group 13 entered intensive care and 2 died.   The two groups were chosen at random, but those treated were on average slightly healthier although also older.  Because this study is small it is inconclusive.  But it does encourage efforts to seek a definitive answer using large, randomized control trials: the industry gold standard.   Until there is proof, few doctors will say vitamin D shields against COVID.  But nearly 80% of Americans suffer from vitamin D deficiency, which intensifies in winter, and those who are deficient would benefit from taking supplements to help bolster the body’s immune system.

    Vitamin D does support the immune system.  The debate surrounds how much of a role vitamin D plays in protecting individuals from COVID or influenza via that immune boosting.  Vitamin D deficiency is associated with many COVID risk factors.  It is rife among black, Hispanic and South Asian people, who are also more susceptible to the new coronavirus and suffer worse outcomes than whites.  A lack of vitamin D is also linked in many studies with a host of conditions such as hypertension and diabetes. These chronic conditions increase the chances of getting COVID and of suffering more serious symptoms and death. 

    Vitamin D is a prohormone that, after processing by the liver and kidneys, is converted into a hormone that acts in different ways on cells in the immune system.  Among other things, it helps avoid bone disorders such as rickets in children and osteoporosis in adults.   Some foods, such as oily fish, have vitamin D, but most diets don’t contain enough to avoid deficiencies.  While sunlight synthesized through the skin is the primary natural source of vitamin D, it must be ultra-violet with a high wavelength (290-310 nanometers).  Light of that wavelength doesn’t penetrate the atmosphere in northern latitudes in winter.  So, the recommendation remains to supplement.  Check with your doctor or registered dietitian about the right amount of vitamin D for you.

    Stephen Fidler; excerpted from The Wall Street Journal