Preventing coronavirus: Are supplements the answer?

With COVID-19 spreading globally and claiming the lives of thousands, millions are worried about the rising risk of infection.

We know that there is no existing vaccine that can prevent us from the new coronavirus.

Without any available medicine, many are wondering -- are vitamins and supplements the secret key to boosting their immune system?

There's currently no available evidence that adding supplements to your diet will help protect you from the virus or speed recovery.

Our ability to fight infection is dependent on our bodies' intricately layered system of physical, biochemical, and cell-specific barriers.

This extends from our external protection, like skin and hair, to the microscopic immune cells and proteins that directly attack harmful microbes.

Many micronutrients are vital to each aspect of the immune system, including vitamins A, B6, B12, C, D, and E, as well as folate, zinc, iron, copper, selenium, and magnesium.

“All cells within the body require nutrients that in turn have an impact on a person’s immune system,” said registered dietitian and nutritionist Maya Feller.

If these vitamins and minerals are our building blocks that fight disease, wouldn’t more of these create bigger, stronger barriers against germ invaders?

While deficiencies in micronutrients can result in increased risk of infections, the reverse might not be true.

So before you hit your local health shop and spend your hard-earned cash, consider the available facts.

What you should know

Despite more than three quarters of the population consuming supplements, most people with healthy eating habits obtain all of their necessary vitamins and minerals through their diet.

Chances are, you’re already meeting your recommended daily intake (RDI) of micronutrients as defined by the National Institutes of Health.

“Nutrition from vegetables, whole fruits, whole grains, and lean proteins provide the body with an abundance of macro- and micronutrients that are essential for optimal health,” said Feller. Utilizing a “food-first approach,” Feller notes that “cells only take up what’s needed and then the rest is excreted -- resulting in expensive urine.”

But this isn’t true for everyone. Deficiencies tend to be more common among those who smoke, get insufficient sleep, follow a restricted diet, or have underlying health conditions.

If you live in certain extreme environments, weather can also impact micronutrient status. Dark winter months can result in decreased vitamin D, while sweating in extreme heat can lead to a loss of magnesium, zinc, and iron.

It might make sense, then, that at least a daily multivitamin would allay any fears of deficiencies and make sure our immune warriors are well-equipped for battle.

However, multiple studies have shown that taking a multivitamin daily does not significantly prevent infections, even in elderly patients in long-term care facilities -- a population that would be more likely to have nutritional deficiencies.

Dr. Thomas Sandora, pediatric infectious diseases physician and hospital epidemiologist at Boston Children’s Hospital, does not routinely recommend any over-the-counter supplements or foods for the prevention of infections.

“Data from randomized trials about the impact of vitamins and minerals on infection rates are mixed,” he said. “While some studies have shown a benefit in some individuals (for example, vitamin D to prevent respiratory infections), the benefit may be dependent on the dose and also on individual factors (such as baseline levels of vitamin D, with those who are deficient at baseline experiencing the most benefit).”

Still, particular micronutrients have been the focus of countless studies, starting with the discovery of vitamin C as the cause of scurvy, a centuries-old disease first seen in sailors with terrible diets.

“There is compelling research looking at vitamin C and zinc reducing the duration and severity of the common cold,” Feller said, but added that “I would not counsel anyone that the aforementioned supplements can produce a cure or prevent a virus.”

What about foods?

Certain foods have also been suggested to fight infections, including garlic.

A fairly recent review of multiple studies suggests that garlic may increase the activity of certain immune cells, but there is not enough scientific data to support its use as a supplement.

There is even less evidence to support the use of other traditional supplements like elderberry or oil of oregano.

Natural vs. organic

If you’re still determined to stay true to your go-to over-the-counter remedies, remember labeling something as “natural” or “organic” is not the same as labeling it “safe.”

While the FDA regulates the safety, efficacy, and manufacturing of prescription drugs, the same regulations do not apply to supplements.

Worse still, some supplements can interfere with prescription medications and have harmful side effects when taken in excess quantities, such as an increased risk of kidney stones with too much vitamin C intake.

“On the whole supplementation should be individualized, meaning there is no one size that fits all,” said Feller.

Where does this leave us?

Per Sandora, “A few general tips that are useful include eating a healthy diet, trying to practice good sleep hygiene, and finding ways to manage stress, which if present over longer periods of time can weaken the immune system’s ability to fight infection.”

But if you’d rather stick to your multivitamin regimen, at least wash and dry your hands before you pop your daily pills.

Chloë E. Nunneley, MD is a pediatric resident physician at Boston Children’s Hospital & Boston Medical Center and a contributor to the ABC News Medical Unit.