Dr. Fauci Recommended Vitamin D and C To Boost Your Immune System

Can some supplements protect against or fight unwanted bacteria and viruses?

When Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, says something about health, people listen. And in a 2020 interview on Instagram with Jennifer Garner, Dr. Fauci talked about specific supplements that may help keep your immune system working robustly.

"If you're deficient in vitamin D, that does have an impact on your susceptibility to infection," said Dr. Fauci. "I would not mind recommending—and I do it myself—taking vitamin D supplements." 

But that's not all: Dr. Fauci also recommended another vitamin. "The other vitamin that people take is vitamin C because it's a good antioxidant. So, if people want to take a gram or so of vitamin C, that would be fine," added Dr. Fauci.

But when Garner asked whether spinach, elderberry, or other supplements could boost your immune system, Dr. Fauci gave his honest opinion: "The answer, to the dismay of many, is no."

So, what vitamins and nutrients boost your immune system? Should you be taking vitamin D and C supplements? Here's what you need to know. 

Can Vitamin D Help Boost Your Immune System?

Dr. Fauci isn't shooting from the cuff here. 

"There is clear evidence that vitamin D does help fight off respiratory infections," Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security, told Health

Vitamin D, also known as calciferol, is a fat-soluble vitamin that's naturally present in a few foods, like:

  • Fatty fish
  • Beef liver
  • Cheese
  • Egg yolks

Your body also produces vitamin D when the sun's ultraviolet (UV) rays hit your skin.

Vitamin D can do many different things in your body, including:

  • Strengthen your bones
  • Reduce inflammation
  • Help with immune function

Vitamin D can be helpful as a supplement. According to Dr. Adalja, some people are deficient in vitamin D. In fact, about 18% of people have inadequate levels of vitamin D. And nearly 5% of people are vitamin D deficient.

As for vitamin D's ability to boost your immune system, some evidence suggests that supplementation protects against respiratory tract infections. A daily dose is the most effective.

In 2017, a study published in the BMJ found that people who took weekly or daily vitamin D supplements were less likely to develop respiratory tract infections than those who didn't. And the most deficient in vitamin D had the most significant benefit.

Can Vitamin C Help Boost Your Immune System?

Dr. Adalja said that the link between vitamin C and immune function is less clear for people who aren't deficient in the vitamin. But Dr. Adalja added, "it doesn't hurt." Still, there is some research to support taking vitamin C supplements, too. 

Vitamin C, also known as L-ascorbic acid, is a water-soluble vitamin and antioxidant that’s naturally present in some foods, like:

  • Oranges
  • Strawberries
  • Broccoli
  • Tomatoes

In 2013, one study published in the Cochrane Database of Systematic Reviews found that people who took vitamin C supplements during a cold reduced the infection by 8% in adults and 14% in children. According to the researchers, those data translated to about a day less of dealing with a cold.

Other evidence suggests that vitamin C supplements may help if you exercise. The 2013 review also examined marathon runners, skiers, and soldiers who took vitamin C supplements. The researchers found that taking 250 milligrams to one gram of vitamin C daily reduced the risk of developing a cold by 50%.

Should You Take Vitamin D and C Supplements?

It’s hard to make a blanket statement that everyone should take a particular supplement. Still, Richard Watkins, MD, professor of internal medicine at the Northeast Ohio Medical University, told Health that those supplements are generally suitable for people. 

Dr. Watkins added that it’s reasonable for people to take vitamins D and C “in normal amounts” to try to boost their immune systems.

The National Institutes of Health recommends that most healthy adults strive to get 15 micrograms of vitamin D a day. In contrast, healthy women should strive to take 75 milligrams of vitamin C, while men should aim for 90 milligrams daily.

If you’re interested in taking a new supplement, it’s a good idea to consult your healthcare provider. Vitamin D and C supplements may interact with medications.

Vitamin D interacts with some statins, steroids, diuretics, and weight-loss medicines. And vitamin C also interacts with some statins, iron supplements, as well as chemotherapy and radiation. Vitamin C increases the rate of iron absorption. While the daily recommended value of vitamin C is not enough to create iron toxicity, it could be possible.

But, experts generally say adding vitamin D and C supplements could be an excellent boost for your immune system.

A Quick Review

Dr. Fauci recommended taking vitamin D and C supplements to support your immune system. But it's important to remember that while getting the daily recommended values of those vitamins is essential, supplements will not necessarily prevent an incoming illness.

Instead, some evidence suggests that vitamins and nutrients play essential roles in reducing the time of a cold. So, next time you're bundled up in bed, sniffling and coughing, you might consider employing vitamins D and C to help kick that nasty bug. 

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