Most people are aware that vitamin C may be helpful to combat the common cold and other respiratory tract infections. But there has been controversy over the years about how effective vitamin C really is in this regard. A great review paper on this subject was published in the Journal of Global Antimicrobial Resistance in 2020. The researchers looked at all the studies involving vitamin C and respiratory tract infections. They explain the multitude of ways that vitamin C supports the body’s immune system and helps to create barriers to viral and other infections in the respiratory tract.

What stands out in the research is the dosage of vitamin C that has been shown to be effective to fight existing respiratory tract infections, including pneumonia. They cite well-designed studies showing that the daily dosage of vitamin C required to shorten the duration of the common cold and/or battle other respiratory infections, including pneumonia, is a 3,000 – 4,000 mg per day. Because immune cells require lots of vitamin C to muster an attack against infectious viruses and bacteria, our immune cells need access to extra vitamin C when we are fighting these infections. Not only do this higher dosage of vitamin C shorten the duration of these infections, including shortening hospital stays, but it has been shown to greatly reduce the risk of life-threatening sepsis and the cytokine storm that can occur if these infections become more severe. Dosages in this range (3-4 gm per day) have also shortened the requirement for corticosteroid drugs, antibiotics and anti-viral drugs.

The key is not to take more than 500 mg of vitamin C at one time, as after that your body’s absorption capacity becomes limited. To raise your vitamin C blood level into the desirable range to fight infections (when using vitamin C supplements) you should take 500 mg, 4-6 x daily with a 2-4-hour interval between each 500 mg dose. The researchers mention that other immune supportive nutrients can also be helpful, such as selenium, zinc, vitamin E, CoQ10, alpha Lipoic acid, N-acetylcysteine, glutathione, L-carnitine. There is also very impressive research showing the important immune-modulating effects of medicinal mushrooms, like reishi, shiitake, cordyceps, turkey tail etc. But on the subject of vitamin C the research strongly supports taking 500 mg, every 2-4 waking hours, when fighting a respiratory tract infection. At the very least this daily dosage of 3,000 – 4,000 mg of vitamin is a good adjunct to other medical treatments to help fight the infection and reduce risk of complications.

I have included the vitamin C review paper in the text below.

Reference:

Haang B.X. et al. Possible application of high-dose vitamin C in the prevention and therapy of coronavirus infection. Journal of Global Antimicrobial Resistance. 2020, 23: 256-262. https://www.sciencedirect.com/science/article/pii/S2213716520302587

Eat Smart, Live Well, Look Great,
Dr. Meschino