Long-time readers know that my “go-to” sources for natural medicines (herbs, vitamins, and supplements) are ConsumerLab.com and Natural Medicines(TM). ConsumerLab has posted about coronavirus and vitamin C:
Vitamin C is vital to the function of leukocytes (white blood cells that help to fight infections) and overall immune system health. Vitamin C is also important for iron absorption, and being deficient in iron can make you more vulnerable to infections in general.
However, even for viruses like colds, the evidence that vitamin C supplements can help is modest at best: Taking high-dose vitamin C (e.g., 500 mg twice daily) before getting a cold may slightly reduce the severity and duration of a cold, but, there is inconclusive evidence as to whether taking vitamin C will help after cold symptoms develop.
Note that the normal, recommended daily intake of vitamin C for adults from the diet and/or supplements is 75 to 120 mg. You can get about 80 to 90 mg from a cup of orange juice or sliced orange, or even more from a cup of sweet peppers, tomato juice, or cut kiwi fruit.
There is no evidence that taking a vitamin C supplement, even at high doses, can protect people from infection from coronaviruses.
Nevertheless, this strategy is being promoted on various websites and in videos on YouTube.
For example, one video recommended taking a daily dose of 5,000 mg of vitamin C. It has since been removed for violating YouTube’s community guidelines (likely as part of an effort by YouTube, Facebook, Twitter, and other social media sites to eliminate misinformation about COVID-19 online, although new posts and promotions for fake coronavirus cures and scams seem to appear daily).
Extremely high doses of vitamin C, 12,000 mg given intravenously twice a day, are currently being tested in COVID-19 patients in China who have developed severe pneumonia (ARDS), are in an ICU, and on a ventilator, but the benefit of this approach has yet to be proven.
This is based upon a review of several studies performed PRIOR to the emergence of COVID-19 that found that a dose of 1,000 to 6,000 mg of vitamin C daily (intravenously or by mouth) shortened the time on ventilation by about 25% for people who required ventilation for over 10 hours, but it appeared to be less helpful for those on ventilators for shorter periods (Hemila J Intens Care 2020).
People sometimes assume there is no harm in taking large doses because vitamin C is water-soluble (i.e. excess vitamin C is excreted from the body), but this is not the case.
In addition to causing gastric distress and diarrhea, high doses of vitamin C over the long-term may increase the risk of cataracts.
High-dose vitamin C can also reduce the effectiveness of certain medications and interfere with certain blood tests.
There are many vitamin C supplements on the market. ConsumerLab has tested many of these and has found several to contain almost 50% more vitamin C than listed on the label (potentially increasing the risk of adverse effects).
ConsumerLab has published its Top Picks in its Vitamin C Supplements Review, which contains additional information about using vitamin C, its benefits, dosing, and potential side effects.
Of course, the most important thing you can do to avoid infection with coronavirus is to prevent exposure by following the latest recommendations of the CDC and World Health Organization and take steps to stay healthy, including getting adequate sleep, keeping up with your daily exercise, and eating a healthy nutritious diet.
© Copyright WLL, INC. 2020. This blog provides a wide variety of general health information only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment from your regular physician. If you are concerned about your health, take what you learn from this blog and meet with your personal doctor to discuss your concerns.