In these times it’s easy to feel overwhelmed and unsure as to how best to support your health and the health of your family so l have come up with a list that l implement with my family and what l recommend in clinic.  

The food we eat is one of the most powerful tools we have to help prevent disease as well as build immune resilience (getting sick and recovering quickly).  Your immune system protects your body by defending against viruses and bacteria which can cause inflammation in the body, resulting in illness and disease. A healthy body certainly begins with a healthy immune system.

There are many ways to heal, nourish and boost your immune system. ALL fruit and vegetables support a healthy digestive and immune system, however some are more immune supportive than others.


When we get infections, it’s NOT the virus/bacteria etc that makes us feel sick. It’s our own immune response with increased free radicals and oxidative stress that make us feel so awful. Each different colour of food provides different antioxidant power to mop up those free radicals, and help us feel better faster – so be sure to eat a rainbow every day. If your kids aren’t the biggest vegetable eaters yet, give them their antioxidant dose with a smoothie packed with fruits AND veggies, use that smoothie to make jelly with grass-fed gelatine or icy poles, sneak grated or pureed vegetables into your spaghetti sauce, soups or whatever other way you can think of – be creative!


Within 30 minutes of eating simple sugars (like glucose, refined sugar, and fructose), the ability of your white blood cells (called macrophages) to “eat up” viruses and bacteria that are trying to invade DECREASES by 50%! And that effect lasts for at least 5 hours. Keeping blood sugar levels healthy has been shown to improve immune system activity.  


These include coconut oil, raw garlic, thyme, oregano, ginger, cinnamon, turmeric, kimchi and other fermented foods, walnut, pomegranate, green tea, apple cider vinegar, and medicinal mushrooms (shiitake, maitake, reishi, cordyceps, turkey tail).  

Increase bone broth consumption as it will support digestion, with over 70% of our immune system based in our digestive system in the form of GALT (gut associated lymphoid tissue).  It contains the amino acids arginine (essential for immune system and liver function), glutamine (which helps with metabolism), and glycine (which aids in glutathione production and also quality of sleep). 

Bone marrow that liquefies over time as your soup simmers is especially beneficial to the immune system. This marrow will contain lipids, especially alkylglycerols, which are vital for the production of white blood cells.


Moderate exercise can boost the production of macrophages, the kind of white blood cells that “eat” bacteria and viruses. However, intense exercise can actually temporarily decrease immune function and increase oxidative stress – so don’t overdo it!


An increase in sleep actually increases not only the number of white blood cells but also their ability to fight viral  infections more efficiently.  On the other hand, loss of sleep even for a few hours at night, increases inflammation within the body, which makes us more susceptible to catching infections and having more severe symptoms. So prioritise sleep.  

If you’ve seen me as a patient you’ll know l’m a big advocate of blue blockers (my favourite brand is baxter blue, my entire family has a pair). These are great for those of us who look at screens after the sun sets.  You see, the amount of light that comes from the screen is about the equivalent of the midday sun so it sends the message to the body to stop production of melatonin- the sleep hormone which helps regulate the body’s internal clock, signalling that it is time to go to sleep.  Studies are also showing that Melatonin is a great adjunctive treatment for co-vid 19  as it may lower the risk of the entrance of the SARS-CoV-2 virus into cells, reduce uncontrolled hyper-inflammation and the activation of immune cells, limit the damage of tissues and multiorgan failure due to the action of free radicals, and reduce ventilator-induced lung injury and the risk of disability resulting from fibrotic changes within the lungs. This means that looking at screens can make it harder to get to sleep.  SO if you are watching a screen after the sun sets be sure to get you and your loved ones a pair to help with sleep.  


Goodness knows for many of us our stress levels are CRAZY high at the moment. Learning how to manage our stress in a healthy way is one of the most important ways we can strengthen our immune system and build emotional and cellular resilience as high levels of cortisol will suppress our immune system.  Our immune system doesn’t know the difference between physical or emotional stress – they both create inflammation. Psychological stress is associated with a decrease in the ability of our white blood cells to kill germs, and  an increase in inflammatory cytokines such as IL-1, IL-6, and TNF-alpha, that may make us feel even sicker.  

My favourite way to help reduce stress is by working with the vagus nerve. If you’ve had a consultation with me then you have probably heard me talk about the many benefits of deep belly breathing.  I bang on about this miraculous nerve to anyone that will listen. 

Babies belly breathe naturally. But somewhere along the way, we started to “suck in our gut” and breathe with our shoulders, and forgot this simple tool to activate our parasympathetic (rest and digest) nervous system and step out of sympathetic (fight/flight/freeze) dominance.  In this moment check in to see how you are breathing- are you shoulders moving up and down with every breath, or are they staying still and allowing your belly to fully expand with nourishing breath?

Practice together – it’s a great way to start your day, and an awesome way to end your day as you snuggle and drift off to sleep.

Belly breathing is easy to do and very relaxing. Try this basic exercise anytime you need to relax or relieve stress.

Sit or lie flat in a comfortable position.

Put one hand on your belly just below your ribs and the other hand on your chest.

Take a deep breath in through your nose, and let your belly push your hand out. Your chest should not move.

Breathe out through pursed lips as if you were whistling. Feel the hand on your belly go in, and use it to push all the air out.

Do this breathing 3 to 10 times. Take your time with each breath.

Notice how you feel at the end of the exercise


Alcohol can severely depress neutrophils, interfering with phagocytes and correct functioning to destroy bacteria and tumour cells. SO try filtered water or mineral water instead. Try raspberries, mint, lemon or blueberries for a powerful antioxidant addition.


Gratitude really is good for our immune system! Practicing a loving kindness meditation not only helps us feel good, studies show that it may actually increase the number and effectiveness of our white blood cells to fight infections. 

Food as Medicine for CO-VID 19

Food really is medicine, and there are specific nutrients that are particularly important to support our immune systems through the COVID-19 pandemic. Below are the top nutrients based on research that are the best way to support your immune system during these times.  


Zinc deficiency is known to increase susceptibility to many infections.   

Studies have shown that administration of a zinc supplement has a potential to enhance antiviral immunity, both innate and humoral, and to restore depleted immune cell function or to improve normal immune cell function.  Zinc has been found to protect or stabilise the cell membrane which could contribute to blocking SARS-CoV-1 entry into the cell.   Zinc and zinc-ionophores (compounds that increase zinc uptake into cells) have been found to inhibit SARS-CoV replication in vitro – that means that it has the potential to prevent the virus from multiplying and wreaking havoc in our bodies.

The current circulating SARS-CoV-2 virus looks very similar to SARS-CoV, so optimising our zinc levels may theoretically have the potential to slow down SARS-CoV-2 replication as well. Zinc has also been found to inhibit replication of other viruses such as influenza virus, rhinovirus (a common cold virus) and coxsackievirus (the hand-foot-mouth disease virus). One reason that chloroquine and hydroxychloroquine may be beneficial is that they are both zinc ionophores, and can help increase intracellular levels of zinc.

One study found zinc supplementation reduced the cold duration by 40%.  Given that zinc deficiency is one of the most common nutrient deficiencies in children and adults, ensuring optimal zinc levels is an important part of any immune support protocol. 

Zinc is associated with multiple enzymes of the immune system and of cells in general. It acts at the primary level of haematopoiesis and in differentiation into immune cells. It is essential to the processes of immune activation and exhibits specific immune responses to immune assault by bacterial, viruses and parasites. 

Food Sources of Zinc

Beef, chicken, shellfish, pumpkin seeds, sesame seeds, chickpeas, cashews, lentils and quinoa.

Potential Zinc Dosages:
The following dosages are based on the Tolerable Upper Intake Levels reported by the NIH  (National Institute of Health) however there are times that l use much higher doses in clinic.

  • 0-1 year: 4-5 mg daily
  • 1-3 years: 5-10 mg daily
  • 4-12 years 10-25 mg daily
  • 13-18 years: 25-35 mg daily
  • 19+ years 25-40 mg daily.


Glutathione is our “master antioxidant,” and is naturally produced in our livers. Glutathione reduces oxidative stress and free radical production, which is vital when we’re fighting infections of any sort.  Glutathione increases natural killer cell activity (our first line of defence against viral or bacterial infections), and also supports our immune response to viruses, bacteria and parasites.  Glutathione and it’s precursor N-acetylcysteine (NAC) have been shown to inhibit viral replication, and depletion of glutathione (for instance by using paracetamol or ibuprofen to reduce fevers) has been found to prolong the duration of viral infections, worsen severity of symptoms, and increase viral shedding from the nasopharynx.  

Glutathione is present in sulfur-rich, cruciferous vegetables. It’s also interesting to know that having bath in magnesium sulphate (Epsom salts) can increase your glutathione levels while also boosting magnesium to promote calm during these stressful times.

Food Sources of Glutathione  

Garlic, broccoli, cauliflower, cabbage, brussel sprouts, kale, swiss chard, bok choy

Potential Glutathione Dosages

There are no clear guidelines for appropriate glutathione dosage for immune support. These dosages are based on what I typically recommend for patients in my practice. However, patients with chronic illness like asthma or autoimmunity may benefit from higher dosages.

  • 1-5 years: 50 mg daily
  • 6-12 years: 100 mg daily
  • 13-18 years: 200 mg daily
  • 19+ years: 250-500 mg daily

Oral glutathione has generally not been found to be well-absorbed, so liposomal glutathione or its precursor, N-acetycysteine (NAC) are preferred. Oral liposomal glutathione at doses of 500-1000mg daily have been found to increase blood glutathione levels and reduce oxidative stress within 1 week, and increase Natural Killer cell activity by up to 400% within 2 weeks! 


Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is a zinc ionophore and therefore facilitates the transport of zinc across the cell membrane.  It is known that zinc will slow down the replication of coronavirus through inhibition of enzyme RNA polymerase.  Quercetin may also prevent SARS-COV from entering cells in the first place.  Both Quercetin and EGCG (epigallocatechin-3-gallate) have been found to inhibit a specific enzyme that is critical for SARS-CoV replication.  In addition, Quercetin was found to protect against sepsis and improve survival by inhibiting the NF-kB pathway.

Quercetin has been shown to impair the binding of the viral spike protein to ACE2 receptors and also reduces pro-inflammatory signals associated with COVID-19.  Studies have also shown that it inhibits COVID-19 viral replication; evidence to suggest that it inhibits coagulation (clotting). 

Food Sources of Quercetin

Red onions (raw), apples, red grapes, kale, spinach, watercress, capers, cherries, green tea.

Potential Quercetin Dosages
Quercetin as a supplement is generally well-tolerated, and side effects are rare at doses of 500-1000mg/day.  When consumed in food, quercetin is safe for pregnant and breastfeeding women. However, there are no studies on safety of quercetin supplements during pregnancy or lactation so please consult with your healthcare provider before taking.

  • 2-4 years: 50 mg daily
  • 4-8 years: 50-100 mg daily
  • 8-12 years: 100-200 mg daily
  • 12-18 years: 200-400 mg daily
  • 19+ years:400-1000 mg daily


Vitamin C is one of our most important antioxidants that soaks up free radicals when we’re sick. Vitamin C plays a vital role in the production of white blood cells that help fight infection and disease.  Vitamin C can significantly reduce the incidence and severity of pneumonia, which is one of the major complications of COVID-19. 

Vitamin C 1.5 grams IV every 6 hours (6 grams total daily), given with hydrocortisone and thiamine has also been found to significantly decrease mortality and prevent progressive organ failure in patients with sepsis, a primary cause of death in patients with COVID-19. In fact, patients treated with the vitamin C protocol had an 8.5% death rate compared with 40.4% in the control group.

A few studies that were done in China using high dose IV vitamin C ongoing, with doses ranging from 10-24 grams per day. Preliminary results were reported to show a significant reduction in lung inflammation and duration of hospital stay.

Food Sources of Vitamin C

Berries, capsicum, broccoli, citrus, brussel sprouts, spinach, asparagus, tomatoes, papaya, mango

Potential Vitamin C Dosages

Vitamin C is water-soluble, which means you pee out any extra that you don’t need or use. Vitamin C has very low toxicity and even at high doses is very unlikely to be harmful, with the most common side effects being diarrhoea, nausea and abdominal cramps, unless you are taking a liposomal form which bypasses these absorption issues.  The following suggested dosages do not exceed the the Tolerable Upper Intake Levels reported by the NIH; however, higher doses are likely safe.

  • 1-5 years: 125-250 mg daily
  • 6-12 years: 250-500 mg daily
  • 13-18 years: 500-1000 mg daily
  • 19+ years: 500-1000+ mg daily

Vitamin A
Vitamin A plays a central role in immunity and deficiency causes broad immune alterations. Vitamin A is essential for the balance between tolerance to host tissues and response to pathogens. It is essential for epithelial membrane integrity.

Vitamin A is one of our most important antioxidants, along with vitamin C and glutathione, to mop up free radicals when we’re sick, and help us recover more quickly. As far back as 1928, vitamin A was known as the “anti-infective” vitamin (28).  In fact, in regions where vitamin A deficiency may be present, the World Health Organization (WHO) recommends a 2-day high-dose vitamin A protocol to treat measles (29). Vitamin A deficiency has been associated with increased risk for infections including influenza, and one study notes that vitamin A deficiency can be considered a nutritionally acquired immunodeficiency disease.

Food Sources of Vitamin A

Fatty fish* (salmon, mackerel, tuna), liver, sweet potato, butternut squash, kale, spinach, carrots, red peppers

*It’s VERY important to buy wild caught salmon, NOT farmed.  The best tuna is skipjack as opposed to yellowfin as the larger the fish, the higher the amounts of heavy metals that they contain. Limit fish consumption to twice a week.  

Potential Vitamin A Doses

Vitamin A is a fat-soluble vitamin, which means that it can get stored in your fat and potentially build up to toxic levels. Vitamin A toxicity is uncommon even at higher doses, and is generally seen only with long-term consumption of vitamin A over 25,000-33,000IU (8,000-10,000 mcg RAE) per day.

There is NO evidence that consumption of vitamin A from B-carotene in food sources increases the risk of birth defects – so eat all the carrots (and other orange vegetables)  you want! However, if you would like to take additional vitamin A supplements in the form of retinyl palmitate, please consult with your doctor first.

The following dosages are based on the Recommended Daily Allowances and Upper Tolerable Intake level of vitamin A per the Nutrient Reference Values for Australia and New Zealand:

  • 0-3 years: 1,000-2,000 IU/day 
  • 4-8 years: 1,500-3,000 IU/day
  • 9-13 years: 3,000-5,000 IU/day
  • 14+ years: 5,000-10,000 IU/day

*If you are pregnant, please note that consumption of excess preformed retinol (such as retinyl palmitate and retinyl acetate found in supplements) is known to cause birth defects. No increase in vitamin A-associated birth defects has been seen at doses of preformed vitamin A from supplements below 10,000IU/day (3,000 mcg RAE/day)


Also known as “the sunshine vitamin” because our bodies naturally produce it when we expose our skin to the sun.  Studies have shown that people supplemented with adequate levels of vitamin D3 during the cold and flu season had significantly lower rates of infection.  With this knowledge it’s no wonder during winter when we have less exposure to the sun and therefore lower vitamin D levels that we are more likely to experience coughs/colds/influenza.

For optimal health l like to see vitamin D at above 100nmol/L which is a far cry from the reference ranges of anything above 50nmol/L being classified as ‘within range’.  Remember that we are looking for optimal health NOT merely the absence of disease.  

A 2017 meta-analysis published in the British medical Journal showed that taking vitamin D supplements daily could help prevent colds and flu, especially in those people who were deficient in vitamin D.   A separate more recent study found that vitamin D supplementation can decrease viral respiratory infection by 70% in people who are vitamin D deficient.

One study of 489 patients who had a vitamin D level measured in the year before COVID-19 testing, the relative risk of testing positive for COVID-19 was 1.77 times greater for patients with likely deficient vitamin D status compared with patients with likely sufficient vitamin D status, a difference that was statistically significant.

Vitamin D has too many immune benefits to mention all of them here. Vitamin D3 increases our body’s production of cathelicidin, an antimicrobial compound, to help fight viral and bacterial infections. Vitamin D deficiency may also be one of the risk factors for sepsis.  Vitamin D has been called a “pro-survival molecule.” In this review of the literature on vitamin D and immunity, the authors conclude that:

“vitamin D not only helps the immune system to be dampened during an excessive or chronic reaction (anti-inflammatory potential) but also to rapidly reach its completion or exhaustion, helping innate cells to kill bacteria or viruses. In this sense, vitamin D maintains its pivotal role as a pro-survival molecule.”

For the moment, knowing that the vast majority of people are vitamin D deficient or insufficient, and knowing how protective vitamin D is for optimal immune system functioning, I continue to believe that vitamin D3 supplementation is an important part of a pandemic immune support protocol. 

Food Sources of Vitamin D

Sunlight (not a food) fatty fish (salmon*, mackerel, tuna*), liver, eggs, dairy, mushrooms

Potential Vitamin D Doses

The Vitamin D Council recommends a daily maintenance dosage of Vitamin D3 of 1000IU per 11kg of body weight, up to 5000IU daily. Given that most children and adults are deficient or insufficient in Vitamin D3, ideally blood levels would be measured to know what dosage is needed to first get to optimal levels and then be able to maintain those levels. In my clinical experience, the ideal 25-OH Vitamin D blood level for optimal immune health is between 100  nmol/L.

Vitamin D toxicity can result in abnormal calcium levels and bone loss, kidney stones, and heart calcifications. However, vitamin D toxicity is very unlikely to occur at adult dosages of 10,000IU per day or less.

  • 0-1 year: 400 IU daily
  • 1-6 years: 1,000 IU daily
  • 7-12 years: 2,000-3,000 IU daily
  • 13-18 years: 3,000-4,000 IU daily
  • 19+ years: 5,000 IU daily


Probiotics, the “good” bugs in our gut have been found to help us maintain a healthy immune response; support our brain for optimal mood, focus, and attention by producing over 90% of our neurotransmitters, serotonin and dopamine; help with detoxification, and even produce their own antimicrobial and anticancer compounds. Studies of the immune benefits of probiotics are vast.  Research suggests that a flourishing network of gut bacteria can help your immune cells differentiate between normal, healthy cells and harmful invader organism.

The health of your gut and that of your immune system is intricately interconnected. 

Probiotics are found in fermented foods.  Fermented foods pack a bigger probiotic “punch” than any probiotic supplement you can take. In fact, kimchi was found to kill the H1N1 influenza virus.  Even small amounts of fermented foods are potent so even if you only have 1/2 a teaspoon to begin with it is still very beneficial.  Fermented foods and probiotics may bolster your immune system by helping it decipher between friend and foe and then target the harmful pathogens (foe).

Food Sources of Probiotics

Fermented foods such as kefir, yoghourt, sauerkraut, tempeh, kombucha, miso, natto and kimchi are important dietary sources of probiotics.   

Potential Probiotic Dosages

Suggested probiotic doses vary widely depending on the specific health concerns that are being addressed.  One study showed a dramatic reduction in fever and upper respiratory symptoms in children who took a probiotic with a specific combination of Lactobacillus and Bifidobacterium daily throughout the cold and flu season.  In addition, I also recommend a “broad-spectrum” probiotic with as many different probiotic strains as possible.  By 2 years of age a child’s microbiome is very similar to an adults hence they can be taking the same as other members of the family.  These are the typical probiotic dosages I use in clinic

  • < 2 years ~ 10-20 billion cfu mixed flora
  • > 2 years ~ 20-50 billion cfu mixed flora


The best food source of the omega-3 essential fatty acids, eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA), is fatty fish. Vegetarian sources of omega-3 fatty acids, like flaxseeds, contain alpha-linolenic acid (ALA) which must be converted to EPA and DHA via the enzyme delta-6-desaturase. Unfortunately, this conversion is not very efficient in most people. So unless you’re a strict vegetarian, I prefer wild-caught, sustainable, fatty fish as a primary source of omega-3 essential fatty acids.

Like vitamin D, the immune benefits of omega-3 essential fatty acids (aka fish oil) are too numerous to list. Omega-3 essential fatty acids reduce inflammation, support healthy immune response, optimise brain and cognitive function, support positive mood, benefit attention and focus, and even gives us healthy skin and hair. Who doesn’t want all of that? Omega-3 essential fatty acids are not just a part of my pandemic immune support plan, they are a part of my family’s year-round plan to stay as healthy and happy as possible.

Food Sources of Omega 3 Essential Fatty Acids 

Fatty fish (salmon*, mackerel, tuna*, anchovies, caviar, chia seeds, hemp seeds, flaxseeds, English walnuts

*It’s VERY important to buy wild caught salmon, NOT farmed.  The best tuna is skipjack as opposed to yellowfin as the larger the fish, the higher the amounts of heavy metals that they contain. Limit fish consumption to twice a week.  

Potential Omega-3 EFA Dosages

Fish oil supplements are, in general, very well-tolerated. If you get “fish burps,” try freezing your fish oil capsule before eating. High doses may cause nausea and loose stools, and occasionally easy bruising or bleeding.  The quality of fish oil is very important as quality is not equal across all brands.  Although there are Australian standards in place the levels of heavy metals allowed is too high from my clinician point of view so please ensure you are purchasing a practitioner only brand of fish oil.  

The dosages I prescribe vary widely, depending on what an individual is presenting with e.g  those with asthma ADHD, autism or anxiety are more likely to be prescribed a much higher dose.  The following potential doses for immune response are based on a combined EPA + DHA dose:

  • 0-1 years: 50-100mg daily
  • 1-5 years: 100-500mg daily
  • 6-12 years: 500-1,000mg daily
  • 13-18 years: 1,000mg daily
  • 19+ years: 1000mg+ daily



Ruth Griffiths

Ruth has had a lifelong interest in and passion for nature, natural medicine, and the human experience. She began her studies in Health Science, Aromatherapy, Remedial Therapies, including Manual Lymphatic Drainage, in Melbourne over 25 years ago. On completion of these studies, Ruth operated a clinic for 8 years in the Grampians region, specializing in […]

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