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Published on January 05, 2021

Can Vitamin D help you prevent COVID-19?

Vitamin D Impact

A vitamin once thought to have a supporting role is now in the spotlight.

Vitamin D, although long recognized for working with calcium to improve bone health, may also play a role in how well our bodies fight off COVID-19, among other diseases and conditions.

An analysis published in the journal Nature in November concluded that among 154 COVID-19 patients, those with a Vitamin D deficiency had worse symptoms and a more intense inflammatory response to the virus.

“This all translates to increase (sic) morbidity and mortality in COVID-19 patients who are deficient in vitamin D,” the report read, and the authors went on to recommend Vitamin D supplements for those at risk for COVID-19.

And, a report published on Medium last month listed two more studies indicating that those with Vitamin D deficiency were more likely to test positive or be hospitalized for COVID. 

That’s in addition to other benefits of Vitamin D, according to the National Institutes of Health and others, such as:

  • It helps the body to absorb the calcium from foods and supplements needed for building strong bones. This helps to prevent brittle bones, a condition known as rickets in children or osteomalacia in adults, and helps to guard against osteoporosis;
  • It helps the nerves carry information between the brain and other body parts;
  • It helps in maintaining cognition and brain health;
  • It plays a role in muscle development and helps guard against falls;
  • It may play a role in preventing diabetes and hypertension, and promoting ocular health;
  • It boosts the immune system, helping in the fight against viruses and bacterial infections.

“They are testing Vitamin D on a lot of different conditions; it might be underappreciated,” said Nicole Clark, a registered dietician with Cape Cod Hospital.

Vitamin D is a fat-soluble vitamin found in foods, either naturally or as an additive, and is also available as a dietary supplement, said Clark. (Fat-soluble means that unlike water-soluble vitamins, vitamin D can be stored in the liver or fatty tissues.) Sunshine also stimulates our bodies to produce it: Ultraviolet rays from sunlight strike our skin and trigger vitamin D synthesis.

But recent research has found widespread Vitamin D deficiencies worldwide, partly due to diet and the fact that many of us don’t get the necessary 20 minutes a day of sunlight that our bodies would require, or we use sunscreens that block UV rays.

A simple blood test can determine if your Vitamin D is where it needs to be. So, how much do you need?

It partly depends on age, Clark said. The NIH recommends 400 IU (International Units) for birth to 12 months and 600 IU for ages 1 to 70. It recommends those over 70 and pregnant women get a daily dose of 800 IU daily.

The best way to get Vitamin D and other nutrients is from food, Clark said.

“Nutrients have interactions in food that are not able to be replicated in supplements,” she said. That said, a supplement may be required, especially for those who can’t get enough from their diet --vegans and the elderly, for example -- or are less likely to be outside.

The most common source of Vitamin D is fortified foods such as milk, nondairy milks and orange juice. But while a cup of milk has 115 to 124 IU, that’s only about a quarter of the recommended daily dose, Clark said. The most efficient food source is fatty fish like trout (645 IU in 3 ounces), salmon (about 400 IU depending on type) or tuna in olive oil (229), she said.

This latest awareness of Vitamin D is good news, Clark said.

“There’s a lot of ongoing research about whether Vitamin D can help. … It’s more common to routinely check people, especially older people who might not eat a lot of dairy foods.”