Vitamin C
For decades, Vitamin C has been used to help prevent the common cold. Among other functions, this vitamin can help maintain healthy skin that provides a barrier to germs and other harmful invaders. In addition, some — but not all — studies suggest it may improve the function of certain white blood cells that fight infection.
In addition, there is conflicting evidence about the potential mortality benefits of high dose Vitamin C for patients with sepsis, the most severe form of systemic infections.
While it’s unclear whether taking a Vitamin C supplement is beneficial for COVID-19, for most people there’s no harm in taking up to 2,000 mg per day (the upper limit set by the National Academy of Medicine).
For smokers and high-risk individuals, it’s definitely worth considering. Vitamin C is water-soluble, so your body will excrete whatever you don’t need into your urine. However, at very high doses, Vitamin C may cause diarrhea or increase the risk of kidney stones (especially in men), so be sure not to exceed 2,000 mg daily.