SARS-CoV-2/COVID-19 has increased interest in supporting immunity and preventing transmission of contagious viruses. There has been a tremendous amount of information put forward to the consumer as methods to do so. Some of this information is vetted and from reliable sources but much of it is not. I would like to offer a non-biased, research-based viewpoint on supplements for immunity and demonstrate some inexpensive over the counter options for you to consider with your health team.
First, two comments on supplements:
The following supplements work through many specific and complex pathways but in general fit into one or more of 3 groups. Some will give the immune system the building blocks it needs to be as strong as possible while others will help to upregulate immune function. Many of those listed below are targeted at minimizing the inflammatory effect after an infection has started. These are important because the severity of a viral illness may be influenced by the inflammatory response your body has to it. In combination, supplementation will help you reduce the chances of contracting a virus and if you do get sick decrease the severity of the illness.
Vitamin C: There are numerous studies supporting Vitamin C for immune support. This is a great review of the literature from 2017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5409678/
While not all research agrees there are several studies that demonstrate fewer viral infections and shortened illness duration with supplementation. Doses in the studies ranged from as little as 50mg to 15,000mg. Most immune supplements provide 1,000mg daily and some advocates recommend closer to 5,000mg. There is no risk of overdosing for vitamin C and any leftover your body will excrete in your urine.
Vitamin D: Truly a hormone in function, Vitamin D plays a role in many body functions including immunity. In this randomized trial, Vitamin D supplementation of 1,200iu daily significantly reduced the likelihood of contracting influenza. This study also demonstrates the relationship of vitamin D deficiency and poor survival with sepsis as well as the mechanism for vitamin D to help prevent infection of droplet spread viruses like the flu and SARS-CoV-2/COVID-19. Recommended doses vary and this is one vitamin that you can take too much of. If possible, you should have your blood level verified prior to long term supplementation. In the short term it is likely safe to add 1,000 to 5,000iu daily unless you have kidney disease or any other medical issue that supplementation would interfere with. Check with your health care team if you have any concerns. Make sure your supplement also has vitamin K to aid in absorption.
Vitamin A: An important companion to vitamin D, this vitamin improves immune function as well. This study demonstrates the mechanism that allows these two to support the immune system together. Supplements need to include sources from both beta-carotene and palmitate. These are frequently found in a good quality multivitamin.
Zinc: Zinc is a well-known modulator of immune function. It will prevent RNA viruses like SARS-CoV-2 and Influenza from replicating. Taken in the form of a lozenge it can help to prevent infections from taking hold but taking an oral form should increase blood levels and help the immune system to fight an infection once established. Doses of 15-50mg daily are recommended in the literature.
Quercetin: This new player to the supplement field has shown promise specifically on SARS-CoV-2 and COVID-19 infections. These studies are not yet published but I hear rumors of promising results. There are studies demonstrating the dominant antioxidant effect and potential for cancer treatment.
Glutathione: Called the “Master Antioxidant” because it is very effective at reducing reactive oxygen species. Oral supplementation has been shown to increase markers of immune function. Liposomal formulations appear to have better bioavailability.
N-Acetylcysteine: A supplement with many medical uses NAC is the precursor for the amino acid L-cysteine as well as Glutathione. Supplementing NAC can increase Glutathione by 30%. It is a powerful antioxidant that is used to help limit the cytokine response to respiratory infections. There are numerous mechanisms proposed for how this supplement may help limit the extent of an infection.
Curcumin: The biologically active compound found in turmeric is a well-known anti-inflammatory. It has been used as a spice for thousands of years likely for this reason. The mechanism have been clearly elucidated and can be found here. Curcumin can be found in supplements in combined “anti-inflammatory” formulations or by itself. 500mg seems to be a common dose but I did not find any literature to support dosing in my search.
Oleuropein (Olive Leaf Polyphenol): is yet another healthy item from the Mediterranean. This supplement helps to reduce inflammation and may increase production of white blood cells when necessary to fight infection. One mechanism of action is clarified here. This supplement can be found as an oil that can be added to salad or blended beverage to decrease severity of symptoms and help your immune system fight an infection should one occur.
There are many more suggestions we could review but the above items have evidence to support their use and are inexpensive to add to your daily regimen. Please remember to ask your physician before adding any supplements and that the above information is for general knowledge only and no individual recommendations or patient relationships are formed.