• Dr. Anthony Fauci, a leading US expert in infectious disease, said in a recent interview that he took vitamin D and C supplements to keep a healthy immune system.
  • There's good science behind his recommendation, with plenty of evidence that being deficient in either nutrient can make you more susceptible to infection. 
  • Fauci said most other immune-boosting claims, however, are useless. There's little evidence other supplements make much difference in preventing illness. 
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The leading infectious-disease expert Dr. Anthony Fauci recommends taking your vitamins now that school has started and flu season is nearing.

Fauci, the director of the National Institute of Allergy and Infectious Diseases, gave an Instagram Live interview with the actress Jennifer Garner on Thursday in which he specifically suggested taking vitamin D and C supplements and said he took them himself.

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

There's a large body of research supporting Fauci's recommendations. Studies suggest vitamin D and C are your best bet for supplementing immune health. However, many of the other products sold for this purpose are useless or worse.

There's evidence to support supplementing vitamin D and C for immune health

Extensive evidence has linked vitamin D deficiency to greater risk of infection, particularly from respiratory diseases like COVID-19.

That's led many researchers to investigate the use of vitamin D supplements to help prevent or lessen the effects of the coronavirus. While the findings are somewhat contentious, since researchers don't fully understand if vitamin D supplements can cause better health outcomes, studies have consistently linked vitamin D deficiency to greater risk of severe infection.

And many people are deficient in vitamin D, especially while sheltering indoors during the pandemic or in darker winter months, since our bodies naturally produce the nutrient in response to sunlight.

People with darker skin may be particularly susceptible, since melanin can slow the process of producing vitamin D. As a result, there's evidence certain people could benefit from supplementing it. 

Similarly, vitamin C is a well-documented antioxidant, and getting enough of it is crucial for a healthy immune system. It hasn't been shown to prevent disease, but there's some evidence it may make it easier for people to recover from illnesses such as the common cold. 

However, neither of these supplements is a cure-all, and too much of either can have serious side effects.

Fauci still recommends masks, social distancing, and hand hygiene as the best practices for keeping yourself and others safe. 

Most other supplements claiming to boost your immune system aren't science-based

Aside from vitamin D and C, there's little evidence that pills, powders, plants, or potions can make a significant difference in warding off illness. 

Garner asked if concerned parents could help boost children's immune systems by giving them more spinach, elderberry, or other supplements.

"The answer, to the dismay of many, is no," Fauci said.

Despite this, many products claim to boost your immune system. These are at best a waste of money and at worst can have harmful side effects.

Colloidal silver, for instance, is commonly touted to cure or prevent disease, but there's no evidence it works, and it can interfere with common medications, cause kidney damage, and even permanently turn your skin blue-gray. 

Chlorine dioxide, advertised as "miracle mineral solution," is even more dangerous. Chemically speaking, the product is industrial bleach, and drinking it can cause liver failure, extremely low blood pressure, and other toxic effects. 

More innocuously, many herbal remedies or vitamins are expensive, and there's no evidence they provide benefits to otherwise-healthy people.

As such, Fauci recommends ditching any other immune-boosting products, and science is on his side.

"Forget about them," he said. "Any of the other concoctions and herbs I would not do."