3 Best Supplements for Building Immune System Resilience

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Hello everyone Floyd Meyer here I am a Physician Assistant with a Master’s in public health, a degree in molecular biology, and I am currently working in physical medicine and rehabilitation. Today we are continuing our series on Resilience which is the ability to remain well, recover, or even thrive in the face of adversity.

Last week we discussed how important micronutrients are to improving your overall resilience specifically your immune resilience. This week we are going to dive a deeper into this topic and discuss specific supplements that can increase your immune resilience.

Now I want to point out that I am not your medical provider, this is not specific medical advice, and these recommendations should not take the place of standard medical care.

Now that we got that out of the way, as we discussed last week an article in the BMJ Nutrition, Prevention & Health stated that, “Consumption of a diet of diverse and varied plant-based and animal-based foods that is consistent with current healthy eating guidelines would be best to support the immune system. However, human trials suggest that the intakes of some micronutrients (vitamins C, D and E and zinc and selenium) needed to optimally support the immune system are in excess of intakes that can easily be achieved through diet alone and in this case supplementation might be considered.” (Calder, 2020)

So let’ discuss which of these supplements that I think can be safe and effective for improving immune resilience.

First up is Vitamin C. Most people already associate Vitamin C with the immune system. In general Vitamin C is thought of as an antioxidant meaning it neutralizes free radicals. The reason that Vitamin C is necessary for proper immune function is mostly due to this antioxidant property. When our immune cells encounter a virus or bacteria in the body they will release large quantities of reactive oxygen species or ROS. These ROS destroy the foreign invader, but they also damage the immune cell that released them. This is where Vitamin C comes in. If the immune cell has enough Vitamin C present they can release the ROS and the Vitamin C will prevent this self-harm from occurring.

The recommended dietary allowance, or RDA, for Vitamin C varies from person to person depending on a number of different factors, but according to the National Institute of Health Office of Dietary Supplements adults over the age of 19 are recommended to obtain at least 90mg daily of Vitamin C for men and 75mg for women to prevent deficiency. Of note they go on to say that “Individuals who smoke require 35 mg/day more Vitamin C than nonsmokers.” Which I think, is a very important point which highlights why when supplementing for immune resilience we may need significantly higher doses.

This caveat shows that when the body is put under stress, like if you are smoking cigarettes, will need more Vitamin C to combat the damage that is being accumulated. This same effect could be seen if someone is ill, or in our case if you were trying to be in the best position possible if the immune system does need to fend off a pathogen.

The Institute for Functional Medicine set their recommendation for Vitamin C at 1-3g or 1000-3000mg daily of Vitamin C in the presence of illness, or to optimize immune resilience for prevention. Per the data synthesized by Dr. Rhonda Patrick and her team on the bioavailability of Vitamin C, I believe that dividing your dose of Vitamin C throughout the day will ensure consistently higher plasma levels. So instead of taking 3g once daily, one could split this dose into 1-2g in the morning and then again in the evening. This would ensure significantly elevated Vitamin C plasma levels throughout the day. Then if symptoms of an infection become apparent the dose could be increased to 1-2g 3-4 times daily. Of note it has been shown that liposomal Vitamin C does provide slightly higher plasma levels than free Vitamin C supplements. (Łukawski et al., 2019)

Next up let’s get into Vitamin D. Vitamin D is an essential steroid hormone that is involved with calcium and phosphate absorption as well as regulation of over 1000 different genes.  Vitamin D can be obtained through the diet in low amounts and through sunshine hitting the skin. Unfortunately, despite its importance 70% of the United States adult population has insufficient levels of Vitamin D meaning levels less than 30 ng/mL. (Liu et al., 2018)

A comprehensive meta-analysis looking at 25 randomized controlled trials concluded that “Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall.” (Martineau et al., 2017)

An exciting recent randomized controlled pilot study looked specifically at how vitamin D supplementation affects the necessity of Intensive Care in patients hospitalized with COVID. They showed that among the 26 patients not treated with Vitamin D, 13 required ICU admission meaning 50%, while out of the 50 patients who were treated with Vitamin D only 1 patient required admission to the ICU! In this study they used high doses of Vitamin D. They administered just over 20,000 IU on day one and then another 10,000 IU on days 3, 7, and then weekly until discharge.

Part of the reason for these effects is due to Vitamin D interacting with the innate immune system increasing its antimicrobial and antiviral activity. (Martineau et al., 2017) The other aspect is a direct effect of Vitamin D on the renin-angiotensin system. (Vaidya et al., 2012) Vitamin D has been shown to increase ACE2 levels and decrease renin levels which has been proposed to be helpful in preventing severe lung disease like that seen in COVID infections.

Thankfully supplementation with Vitamin D is easy and affordable. The best way to supplement is to first get your Vitamin D levels checked with blood work. Most medical providers will order this for you along with your yearly labs, and/or you can pay cash to get them checked yourself.

Ideal Vitamin D levels are between 40-60 ng/mL. If you are low or presume that you have low levels due to living in a northern latitude and or spending most of your time indoors then supplementation may be necessary. Supplementation with Vitamin D3 at ranges between 2000-5000IU per day for a period of a few weeks to a few months have been shown to be effective at raising Vitamin D levels to the optimal range. Of note Vitamin D is a fat soluble vitamin and it is possible to take too much Vitamin D.

We also have the ability to produce our own Vitamin D through sun exposure. The amount produced is affected by multiple variables from age to body fat to latitude. Just recently multiple large organizations including the Endocrine Society, the American Association of Clinical Endocrinologists among others published a joint statement stating that, “One of the best sources of vitamin D is through 15-30 minutes of direct sunlight exposure on your skin daily (taking care to avoid sunburn).”

Through both regular safe sun exposure and supplementation you should be able to easily raise your Vitamin D levels to the ideal 40-60ng/mL improving your overall immune resilience.

Finally let’s discuss Zinc. Zinc is essential to optimal immune function, and it has been shown to specifically inhibit the reproduction of viruses and bacteria. Even mild Zinc deficiency can impair the immune system. Many people already know that Zinc is beneficial for the common cold in the form of Zinc lozenges.  In a meta-analysis posted in the Open Forum Infectious Diseases they showed that people supplementing with between 80 and 92mg/day in divided doses of Zinc Acetate lozenges starting at the onset of cold symptoms had a 3 fold increase in recovery rate from the common cold. Specifically they stated that “On the 5th day, 70% of the zinc patients had recovered compared with 27% of the placebo patients.” (Hemilä et al., 2017) Other studies looking at the effects of Zinc at doses less that 75mg/day have not been as successful.

There are safety concerns with Zinc supplementation. Specifically it leading to impairments in the absorption of other nutrients like copper and iron, as well as increasing prostate cancer risk in long term supplementation. For this reason, I would avoid daily supplementation. Instead it would be best to have some Zinc Acetate lozenges around for the first signs of a viral illness. Then at that time take between 80-90mg of Zinc daily in divided doses throughout the day ideally at times farther away from your meals as to prevent any decrease in absorption. This will ensure an optimally functioning immune system when you need it most. Of note Zinc Gluconate has also been shown to be effective for cold relief although slightly less than the Zinc Acetate according to the above mentioned meta-analysis.

So there you have it, my 3 favorite supplements to increase your immune resilience.

Vitamin C taken at doses of between 1-3g in divided throughout the day can be effective in raising plasma Vitamin C levels which can be helpful at the first sign of infection or taken preventatively.

Next having adequate Vitamin D levels, ideally between 40-60 ng/mL, has been shown to be protective against acute respiratory tract infection. This can be achieved through supplementation with between 2000-5000IU per day for 1-3 months with blood testing being recommended as it is fat soluble and possible to take too much.

Lastly, Zinc Acetate or Gluconate lozenges taken at the onset of cold symptoms had a 3 fold increase in recovery rate from the common cold. The doses shown to be effective were between 80-90 mg/day, and were taken in divided doses throughout the day. It can also be helpful to take a zinc ionophore like quercetin, curcumin, or EGCG (green tea extract) to get the zinc into your cells where you actually need it.

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It has never been more important to ensure optimal micronutrient status increasing your overall resilience. Unfortunately, Americans are known to be extremely deficient in a number of vitamins and minerals.

So make sure you are eating a lot of fruits and vegetables each day, eating a range of different colored vegetables, and supplementing appropriately.

If this resonated with you please share with your friends and family and subscribe and follow for more of this content. The time for action is now. Again this is Floyd Meyer. Have a great day!


American Society for Bone and Mineral Research (ASBMR), Endocrine Society, American Association of              Clinical Endocrinologists (AACE), European Calcified Tissue Society (ECTS), the National        Osteoporosis Foundation (NOF), and the International Osteoporosis Foundation (IOF). (2020,       July 9). Joint guidance on vitamin D in the era of COVID-19 [Press release]. Retrieved from https://www.endocrine.org/news-and-advocacy/news-room/2020/joint-guidance-on-vitamin-d

Castillo, M. E., Costa, L. M., Barrios, J. M., Díaz, J. F., Miranda, J. L., Bouillon, R., & Gomez, J. M. (2020).          “Effect of Calcifediol Treatment and best Available Therapy versus best Available Therapy on       Intensive Care Unit Admission and Mortality Among Patients Hospitalized for COVID-19: A Pilot              Randomized Clinical study”. The Journal of Steroid Biochemistry and Molecular Biology, 105751.        doi:10.1016/j.jsbmb.2020.105751

Calder PC. Nutrition, immunity and COVID-19. BMJ Nutrition, Prevention & Health 2020;0. doi:10.1136/       bmjnph-2020-000085

FoundMyFitness Topic – Vitamin C. (n.d.). Retrieved July 21, 2020, from              https://www.foundmyfitness.com/topics/vitamin-c

FoundMyFitness Topic – Zinc. (n.d.). Retrieved July 21, 2020, from              https://www.foundmyfitness.com/topics/zinc

Hemilä, H., Fitzgerald, J. T., Petrus, E. J., & Prasad, A. (2017). Zinc Acetate Lozenges May Improve the         Recovery Rate of Common Cold Patients: An Individual Patient Data Meta-Analysis. Open Forum       Infectious Diseases, 4(2). doi:10.1093/ofid/ofx059 

Holick, M. F., & Chen, T. C. (2008). Vitamin D deficiency: a worldwide problem with health        consequences. The American Journal of Clinical Nutrition, 87(4), 1080S      1086S. doi:10.1093/ajcn/87.4.1080s 

Liu, X., Baylin, A., & Levy, P. D. (2018). Vitamin D deficiency and insufficiency among US adults:           prevalence, predictors and clinical implications. British Journal of Nutrition, 119(08), 928              936. doi:10.1017/s0007114518000491 

Łukawski, M., Dałek, P., Borowik, T., Foryś, A., Langner, M., Witkiewicz, W., & Przybyło, M. (2019). New            oral liposomal vitamin C formulation: properties and bioavailability. Journal of Liposome         Research, 1–8. doi:10.1080/08982104.2019.1630642 

Martineau, A. R., Jolliffe, D. A., Hooper, R. L., Greenberg, L., Aloia, J. F., Bergman, P., … Camargo, C. A.  (2017). Vitamin D supplementation to prevent acute respiratory tract infections: systematic      review and meta-analysis of individual participant data. BMJ, i6583. doi:10.1136/bmj.i6583

How to get vitamin D from sunlight. (n.d.). Retrieved July 24, 2020, from              https://www.nhs.uk/livewell/healthy-body/how-to-get-vitamin-d-from-sunlight/

Office of Dietary Supplements – Vitamin C. (n.d.). Retrieved July 21, 2020, from     https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/

The Functional Medicine Approach to COVID-19: Virus-Specific Nutraceutical and Botanical Agents.    (n.d.). Retrieved July 24, 2020, from https://www.ifm.org/news-insights/the-functional        medicine-approach-to-covid-19-virus-specific-nutraceutical-and-botanical-agents/

Vaidya, A., & Williams, J. S. (2012). The relationship between vitamin D and the renin-angiotensin    system in the pathophysiology of hypertension, kidney disease, and diabetes. Metabolism,         61(4), 450-458. doi:10.1016/j.metabol.2011.09.007

Vitamin D may reduce susceptibility to COVID-19-associated lung injury. (n.d.). Retrieved July 24, 2020,   from https://www.foundmyfitness.com/episodes/vitamin-d-covid-19


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