The Vitamin D Question

Why has New York City been slammed so hard by COVID-19? There are almost as many theories as lights gone dark on Broadway. But one obvious factor does not seem to draw the same blame as our crowds, our subways, our leadership or our location at the crossroads of the world.

Which is odd, since New York doctors all know about it. Vitamin D deficiency is, well, epidemic among New Yorkers. And in just the past few days three separate studies, from the US, the UK and Indonesia, have reported a strong correlation between death rates from COVID-19 and vitamin D deficiency.

“Our analysis shows that it might be as high as cutting the mortality rate in half,” Professor Vadim Backman of Northwestern University said of the correlation between vitamin D deficiency and COVID-19 deaths found in ten countries, including the United States. “It will not prevent a patient from contracting the virus, but it may reduce complications and prevent death in those who are infected.”

The strong correlation does not prove causation, of course, and the researchers recommended further studies. But health professionals say there is no reason to wait to reduce the prevalence of vitamin D deficiency, which has been well known for years.

“Vitamin D is typically much lower in New Yorkers,” said Dr. Eric Ascher, who has offices in Chelsea and on East 76th Street, around the corner from Lenox Hill Hospital Northwell Health, where he is affiliated. “Buildings are so high, everybody’s working indoors.”

Vitamin D deficiency is so prevalent here that Ascher says, “I’m more shocked when a patient has a normal vitamin D level.” Ascher says he regularly prescribes vitamin D supplements and urges patients to consume dairy products and get more sun.

Public Health Actions

A vitamin deficiency may seem trivial against the dramatic risks of a crowded 2 train or a presidential news conference. But this illustrates a larger conversation that is only barely getting started.

Hopes for an end to the lockdown have rested heavily on a scientific or medical breakthrough. A vaccine or effective treatment will be welcome. But increasingly experts are pointing to the importance of basic public health actions. They say these can both reduce the spread of the coronavirus, through testing, tracing and sanitary measures, and the severity of COVID-19, by reducing conditions that make patients more vulnerable.

“We are only as healthy as our most challenged residents,” said Dr. Oxiris Barbot, New York City’s Commissioner of Health and Mental Hygiene. “It is inevitable that we are going to have a second wave and so we need to not only prepare for that but really look toward seeing this as an opportunity to re-imagine what it means to live in a world where we support people’s total health.”

This involves everything from improving overcrowded housing to alleviating concentrations of chronic disease in communities of color, she said.

Several chronic conditions that exacerbate Covid-19 are well known, including diabetes and heart disease. But vitamin D deficiency may be just as significant, according to the new research. D deficiency is particularly severe among African Americans and Hispanics. They also are suffering higher deaths rates from COVID-19.

It has been nine years since public health professors Kimberly Forrest, a biostatistician, and Wendy Stuhldreher, a nutrition epidemiologist, both professors of public health at Slippery Rock Uiniversity, part of the University of Pennsylvania, analyzed government data and concluded that 40 percent of Americans were deficient in Vitamin D, a figure still cited as authoritative.

“This entire pandemic has been very interesting to me,” Stuhldreher wrote by email.

“What role Vitamin D played or might play in the epidemic is not determined. However, vitamin D does have a role with keeping the immune system healthy. I have wondered why California had such different death rates than New York. Was it sunshine related for several reasons? UV light killing the virus? Increased exposure to sunlight, all allowing people to have a higher blood level of Vitamin D? Who knows.”

Immune Overreaction

A conclusive study would require analyzing blood of COVID-19 patients for D deficiency, an approach that so far only appears to have been taken in the study in Indonesia.

The study in Indonesia looked at 780 confirmed cases of Covid 19 since March 2, when the pandemic reached there. Of the 380 patients who died, all but 16 were found to have inadequate Vitamin D. Conversely, of the 400 who lived all but 28 had normal vitamin D.

When the authors statistically adjusted the results for age, gender and other preexisting medical conditions, they concluded that Vitamin D deficient patients were 19 times more likely to die.

There are no studies yet of Vitamin D and COVID-19 in New York City, a health department spokesman said. But in addition to the report from Backman, who is the Walter Dill Scott Professor of Biomedical Engineering at Northwestern’s McCormick School of Engineering, a similar correlation was found in a study of 20 European countries. In particular, “Vitamin D levels are severely low in the aging population especially in Spain, Italy and Switzerland. This is also the most vulnerable group of the population in relation to COVID-19,” according to the report lead by Dr. Cristian Ilie, Research & Innovation Director at The Queen Elizabeth Hospital Foundation Trust.

Vitamin D is usually associated with healthy bones. But it also has been shown to play a crucial role in regulating our immune system. A furious overreaction of the immune system, called a cytokine storm, is a key factor in COVID-19 deaths, according to a paper released on May 13 by a team of experts at Zunyi Medical University in China.

“Vitamin D supplementation reduces the risk of respiratory infection, regulates cytokine production and can limit the risk of other viruses such as influenza,” Dr. Tom Frieden, former director of the Centers for Disease Control, wrote a few weeks ago, even before some of the new research became available. “This is especially important for people who are Vitamin D deficient – and, surprisingly, that might include more than 40 percent of US adults.”

"Anything we can do to strengthen our resistance is a step in the right direction," Frieden added. "We can do lots of things to improve our resistance to infection. These include getting regular physical activity, getting enough sleep, stopping smoking and other tobacco use, and, for people living with diabetes, getting it under control. Taking a multivitamin that includes Vitamin D, or a Vitamin D supplement, probably can’t hurt, and it might help."