Practical Nutrition Strategies for COVID-19

Happy July friends! My, so much has happened since I last blogged in April. It has been hard to even keep up. I’ve been trying to write this post about nutrition and Covid-19 for weeks now, and I think it’s even more timely now that the economy is opening up and our risk for exposure is going to increase.

This month I wanted to share some nutritional insights from recent research on Covid-19 and practical steps you can take to bolster your health as you start to venture back out into the world. Let’s face it. The likelihood that we come in contact with this virus at some point over the next year is high, so let’s give our bodies all the support we can.

I’m going to warn you this post is long. I really want to share all the new findings and insights being published almost every day. However, if you lose interest, skim down to the end where I share a recap of the helpful nutrients, supplements, and lifestyle changes you can make.

Nutrition Strategies for COVID 19

There’s SO much research going on right now. While we may not “see” it, labs across the world are in a flurry to try and figure out how to combat this virulent virus. As of the day I am publishing this, there have now been 12.9 million confirmed cases in the world and 571,000 deaths. Of those cases, over 3 million are in the US alone and we share 137,000 of the deaths. Sadly we know this will continue to increase.

It is encouraging that most are taking the proper precautions and for the most part taking this seriously. The truth of the matter is, though, that this virus is going to be with us for a long time coming. I personally don’t see how we can keep the economy closed forever. The social and emotional impacts start to outweigh the risks of the virus. At the same time, we need to stay vigilant.

Certainly we see that we have very vulnerable populations in this pandemic and those that skate by without barely a symptom. The magic question is, how do we get less of the former and more of the latter? A slew of recent research has come out to try and give clues as to why some have such dramatic symptoms that lead to death (the “cytokine” storm that is frequently referenced) and why others never need to venture even close to a hospital for treatment.

The answer may lie in a variety of health dimensions: nutritional status, overall immune function, possibly genetics, the relationship with various co-morbidities, and even where you live in the world. All of these might help explain your particular risk factors. I am going to run through several nutritional aspects, explicitly referencing current research, to help elucidate some factors that might help YOU be as prepared as you can against a virus we likely all have to face at some point in the coming years.

General Nutrition

General nutrition status is a good place to start. It is well documented that malnutrition is a contributor to immunodeficiency. When an infection occurs, the malnourished person quickly exhausts their nutrient supply and the immune system is weakened. It cannot fight at full strength. Our immune systems are dependent upon a variety of micronutrients to function. While ALL nutrients are in some way important for overall immune health, the micronutrients with the strongest evidence for direct immune support, particularly against Covid-19, include Vitamin C, D and Zinc. Antioxidants such as selenium and glutathione have been shown to have relevance, and even the hormone melatonin may be vitally useful.1,2 Let’s take a look at each of these.

Vitamin C

Many in the medical community have been looking at Vitamin C and its impact with Covid. It is an important cofactor for numerous physiological reactions in the body. It has already been shown to play an important role in fighting flu viruses, especially when given in the early stages of infection.3 Results have been mixed in its effectiveness for use against the common cold, however there is some evidence that it may shorten the duration. Evidence has also indicated that those with inadequate Vitamin C intake are at greater risk for pneumonia and other severe respiratory infections.2 Given the relative safety of Vitamin C supplementation, even at higher doses, this would certainly be one to consider in an overall prevention strategy.

A slightly controversial topic is the use of IV Vitamin C therapy in Covid-19. One of the primary ways Covid-19 kills is by causing a cytokine storm in the lungs. This leads to Acute Respiratory Distress Syndrome (ARDS) whereby the body cannot get enough oxygen due to large amounts of free radicals and cytokines being produced (oxidative stress). The theory is that the administration of anti-oxidizing agents (Vitamin C in this case), would help alleviate the “storm” and reduce the progression of ARDS. Several cases have been documented where it has been effective.4 It appears that this level of administration should only be used in severe respiratory conditions that require hospitalization, so this is not something to consider prophylactically at home. If you or someone you love does contract Covid and is hospitalized, discussing intravenous Vitamin C with your health team might be advantageous.

Vitamin D

Vitamin D has long been thought to be supportive against viral attack. It serves many useful purposes, including helping to maintain tight junctions in the lungs, enhancing both parts of the immune system (innate and adaptive immunity), and increasing the expression of genes responsible for producing potent antioxidants such as glutathione.5

More specifically, Vitamin D appears to increase anti-microbial peptides in the body, reduce the over-production of pro-inflammatory cytokines (which can reduce the progression to a cytokine storm), and increase the expression of anti-inflammatory cytokines.5

This is likely why there is evidence Vitamin D deficiency increases the risk for developing respiratory disease and is associated with the hyper responsiveness of airways. A deficiency is also linked to increasing the risk for influenza and other viral respiratory infections.6

These attributes have caused researchers to postulate that adequate vitamin D status could be highly beneficial in preventing deaths from Covid-19. But what dose? What blood levels are we looking for?

It is still too early to tell. One observational study noted that serum levels above 38 ng/mL were ideal for reducing the risk for respiratory infections. Others have suggested 30 ng/mL as adequate, while others have mentioned upwards of 40-60 mg/mL as the target.7

In practical terms it is hard to translate that into recommended supplement doses. It depends on the level of deficiency and one’s ability to absorb in the gut. My typical recommendation for most people is 2,000IU/day. If deficiency is found, I often increase that to 5,000IU per day for a couple months, then gradually reduce. In cases of severe deficiency, doctors have administered upwards of 50,000IU weekly, and in the research there were cases of over 100,000IU’s being recommended.2 This is obviously only in clinical settings. Definitely discuss with your doctor to find the right dosage that, with time, should get your serum levels at minimum above 30, and ideally in the 40-60 range.

*Since starting to write this article I noticed a lot of new research and theories being proposed for Vitamin D and Covid-19. Definitely one to keep your eye on!


Most of us already think of zinc when it comes to immune health, especially during cold and flu season. Just about every immune boosting remedy out there incudes zinc as part of their formulation, and with good reason. Zinc is critical to numerous enzymatic reactions that support the function of the immune system. Specifically it helps increase the number of circulating immune cells and decreases pro-inflammatory mediators.2 In regards to the common cold, it is believed that zinc helps inhibit viral replication and attachment to the mucous membranes of the nasal passages, decreasing its spread and shortening the duration of the illness.7 Some studies have shown zinc supplementation beneficial in children, decreasing the risk for morbidity related to diarrhea and respiratory illness.1

Researchers have recently theorized that zinc might be immensely beneficial in the fight against Covid-19. While data is lacking given the newness of this virus, the knowledge that zinc deficiency increases susceptibility to disease, along with the numerous anti-viral roles zinc plays, have caused speculation that zinc may be preventative of Covid as well as supportive in improving symptoms and outcomes. The elderly are particularly at risk for zinc deficiency and might be one reason why this population has been hit especially hard.

The RDA for zinc is 8mg/day for women and 11mg/day for men. Make sure to be getting dietary sources of zinc where possible. Good food sources include meats and organ meats, shellfish, nuts, beans, eggs, and whole grains. Supplements can be a consideration, especially for those not consuming the aforementioned foods and for those who may not be absorbing nutrients efficiently.


Selenium is not usually one that first comes to mind for immune health and support. Surprisingly, there is a lot of curiosity and research going into this important antioxidant and its potential role in reducing morbidity from Covid-19. Several studies have shown that selenium deficiency increases ones susceptibility to viral infections.9 Older adults tend to be at greater risk for deficiency, again potentially indicating why this population has been the most at risk. As a potent antioxidant, selenium helps tamper down inflammation from infections and reduces oxidative stress, which can exacerbate respiratory conditions.10

Selenium is derived from the soil and thus found in a variety of foods. Some of the highest sources include nuts and seeds (especially Brazil nuts!), seafood, meats, eggs and leafy greens. The RDA for adults is 55 mcg per day, which is easily achievable if eating a balanced diet. There are supplement options, however be aware there is the risk of selenium toxicity in high doses.


Glutathione is another potent antioxidant. In fact it is known as our “master” antioxidant. It is a powerhouse in reducing the oxidative stress resulting from infections and general inflammation. It also helps regenerate other antioxidants such as Vitamins E and C. Several studies have already shown that adequate glutathione levels improve the immune system’s ability to respond to viral infections. There is also evidence that glutathione itself inhibits viral replication at certain points of the viral life cycle and subsequently appears to help decrease overall viral load and risk for a cytokine storm in the lungs.11

Interestingly, many ties have been drawn between glutathione deficiency and poor outcomes in Covid-19. First, endogenous glutathione production tends to decrease with age, leading to deficiency in many older people. Also, those with co-morbidities tend to have lower glutathione levels as their glutathione is rapidly being used to deal with the oxidative stress from those other conditions. Smoking results in low glutathione levels as well. Men, who have been noted to have a higher risk of death from Covid-19 than women, in general tend to have lower glutathione levels than the opposite sex. Poor diet may also play a role in glutathione status.11,12

Because the majority of our glutathione is endogenously produced, providing our bodies with the right cofactors is one of the most important steps in ensuring adequate production. A well-balanced diet is the best course of action, specifically one that provides sulfur compounds (garlic, onions, broccoli, cauliflower, leafy greens, leeks), selenium rich foods (as already discussed), and cysteine rich foods (meats, grains, seeds, eggs, dairy).13

The use of supplemental glutathione has had mixed reviews. Many research papers have reported it to be poorly absorbed and not effective at raising levels. Others have shown it to have some effect, but only in high doses, and a few studies noted that sublingual and intravenous were better absorbed than oral supplementation. Liposomal forms might also be a better method. The research seems to indicate that if taken in supplemental form, dosages above 500mg appear to be the most effective.

N-acetylcysteine (NAC) supplementation is another consideration in raising glutathione levels. As the main precursor to glutathione and as a supplement that is typically much better absorbed, it may help raise levels more quickly than oral glutathione and potentially even better than diet, especially if there are gene polymorphisms that are inhibiting the endogenous production of glutathione. In fact, NAC has already been noted as safe and effective for helping to prevent viral respiratory infections.12

Clearly we need much more research in this area and specifically around effective supplementation. In the meantime, general healthy diet, reducing stressors, and improving overall health status to the best of our ability is so far our best support for enhancing glutathione levels in the body.


This one might sound surprising. Melatonin, really? Isn’t that a hormone for sleep? Indeed. But it also has other important roles including controlling inflammation, reducing oxidative stress and modulating the immune system. Who knew?

First off, we know melatonin is important for our circadian rhythm, aka the sleep-wake cycle. Poor sleep, which in some may be related to dysregulation in melatonin production, down-regulates our immune system.14 When melatonin is functioning at normal levels it enhances immune function by increasing the proliferation of various types of immune cells. Chronic sleep deprivation, therefore, may be particularly harmful in Covid-19 cases, and correcting melatonin levels may be important not only in improving sleep, which improves immune function, but also as a direct actor in immune regulation.15 

Melatonin also has strong anti-inflammatory effects. It is known to down regulate enzymes that promote ongoing inflammation and can even suppress the production of inflammatory mediators that are involved in ARDS. It appears to have a down-regulating effect on pro-inflammatory cytokines and helps increase the production of specific anti-inflammatory ones. Studies have even shown, at least in the mouse model, that increased levels of melatonin can reduce the ability of macrophages and neutrophils to overwhelm the lungs, thereby reducing the risk for a cytokine storm.16 

Melatonin also appears to reduce oxidative damage resulting from the inflammatory process by up-regulating anti-oxidative enzymes (superoxide dismutase, glutathione peroxidase, reductase and catalase). It may also act directly as a free-radical scavenger itself and thereby be protective against the negative effects of widespread inflammation. In fact, melatonin can bind up to 10 free radicals per molecule whereas Vitamins E and C can bind just one!16

 Interestingly, we have seen that the people most at risk for Covid-19, namely the elderly and those with underlying health conditions, are those that tend to have the lowest melatonin levels. Those who so far appear to be at the least risk, including children and young, healthy adults, tend to have the highest levels. Pregnant women also have higher levels of melatonin and so far do not appear to be at any increased risk over non-pregnant, healthy adults.17 

If one does decide to supplement with melatonin, what dosage is ideal? Some researchers suggest as little as 500mg per day would provide benefit in terms of reducing the risk for a cytokine storm in viral respiratory diseases.15 Often people utilizing melatonin for sleep use higher doses. Anywhere from 1 – 10g per day appears to be safe and well tolerated, however starting on the lower end is always recommended. In terms of safety, there are few issues with toxicity reported, even in doses well above 10g per day, although it is always important to discuss supplement use with a doctor before adding to your regimen.

Other nutrients and considerations

Other nutrients that deserve a quick mention include Vitamin A, Vitamin E, the B vitamins and magnesium. All of these, and frankly many others as well, provide more of what is required for the immune system to function. Deficiencies in any of these areas may have an effect on how we are able to cope with and respond to infections, as many of these interact in a synergistic way. This is why a healthy diet is paramount, especially now.

We already mentioned co-morbidities, but obviously the more health issues one has will tax the immune system and lessen its ability to respond to a new infecting agent. Obviously this isn’t something one can change overnight, but working towards that with diet and other lifestyle changes would certainly help. Other factors that can dampen the immune response include chronic stress, environmental pollutants, lack of physical activity, genetic polymorphisms that affect synthesis of important compounds inside the body, and clearly poor sleep.

While certainly this virus is nothing to mess with and all necessary precautions should be taken as recommended by our health officials, there is actually a lot of control we DO have in how our immune system functions and how we can best confront an infection should it occur. See the cheat sheet below for some ideas to implement this summer before colder weather returns and infection levels start to rise even more.

REMEMBER: Always discuss supplement use with your doctor or trusted health professional as there may be interactions with other medications/supplements or it may simply not be best for your health at this point in time.


Nutritional Recommendations for Enhancing Immunity:

Healthy Diet! Always number one. Seek professional advice if you need help finding the right diet for you. Mediterranean style or anti-inflammatory style diets are good ones to check out for guidance.

Vitamin C

Supplement: Around 500mg per day during cold and flu season

Dietary sources: citrus fruits, red & green peppers, broccoli, strawberries, cantaloupe, kiwi

Vitamin D

Supplement: 1,000-2,000 IU/day

Dietary sources: Fatty fish (salmon, tuna, mackerel, sardines), fish liver oil, enriched food products

*Have your vitamin D levels checked at your next physician visit


Supplement: 10-30 mg per day

Dietary sources: meats and organ meats, shellfish, nuts, beans, eggs, and whole grains


Supplement: 50-100mcg per day

Dietary sources: Nuts and seeds (especially Brazil nuts!), seafood, meats, eggs, dairy products, and leafy greens


Supplement: 500mg or more per day

Dietary sources: A well balanced diet to provide the necessary cofactors! Specifically sulfur compounds (garlic, onions, broccoli, cauliflower, leafy greens, leeks), selenium rich foods (see above), and cysteine rich foods (meats, grains, seeds, eggs, dairy).


Supplement: Only take if needed, but especially if you tend to have poor sleep. Anywhere from 500mg per day up to several grams per day.

Other Nutrients and Lifestyle Factors

*A general multivitamin may be beneficial, especially during times at greater risk for cold/flu. Personally my favorite to recommend is Pure Encapsulations ONE which contains most of the nutrients already listed (apart from glutathione and melatonin).

*Reduce stress, as much as you are able. Stress negatively effects our immune function. Try deep breathing, yoga or other exercises, talking with friends or a  therapist, or even a nice long bath. Whatever chills you out, do that.

*Exercise! Make sure to move your body. Get your heart rate up and work those muscles. It helps reduce that pesky stress we just talked about and can give a boost to your immune system.

Wishing you the BEST of health in the coming months. We will get through this!



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