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Essential steps to boost your natural defence

Magdalena Marvell is a Nutritional Practitioner and Founder of the Persea Clinic which helps support clients who want to optimise their health in areas such as gut health, hormonal balance, skin conditions, weight management, family nutrition.

Through these unprecedented times it’s especially important that we take care of our bodies to help build our natural defences. Staying strong and boosting our immunity may help us to reduce emotional and physical stress thus helping us to cope through these uncertain times.

The government has requested we socially distance, avoiding public spaces and working from home where possible. These restrictions have put a huge impact on our lives. Limited access to food (for some) can be especially challenging to maintain nutritional balance and wellbeing. Perhaps now is a good time to asses our waste habits in the kitchen and prove our resourceful nature by re-visiting freezers, larders, cupboards and gardens or experiment with home baking and preserving.

Supporting our innate immune system can potentially help us to fight off viral infections and also reduce its severity. Here is a short guide on how you can boost your immunity by using products found at home or simply adjusting our lifestyle habits:

Beta Glucans – Shown to have immune boosting properties are a group of complex carbohydrates found in foods such as: oats, barley fibre, shiitake mushrooms, algae, seaweed and bakers yeast. Research shows that beta glucans found in baker’s yeast are more potent than beta glucans found in mushrooms. Baker’s yeast improves the ability of white blood cells to detect and kill potential pathogens.

Once consumed the yeast is collected by Peyer’s Patches (small masses of lymphatic tissue) within the intestines and then transported by macrophages (cells located in the Payer’s patches) to the immune organs within the body. The macrophages break down the yeast into smaller particles which bind to the most plentiful immune cells in our bodies, neutrophils which then move rapidly to identify and defeat foreign pathogens. A study published by the Journal of the American College of Nutrition1 suggests that daily supplementation of the baker’s yeast may reduce upper respiratory tract symptoms and improve mental/physical energy levels in psychologically stressed people2.

This shows that bakers yeast beta-glucan has an ability to reduce the impact of stress on the immune and hence lowers our vulnerability to develop upper respiratory symptoms.

So if you come across any dry shiitake hiding at the back of your cupboards and perhaps a bag of barley then add them together to create an amazing stew, risotto or even a ramen type broth to help you to fight off potential infections!

S. Boulardii – The probiotic yeast is a non-pathogenic yeast which is antibiotic resistant and it influences the gut associated immune system. S. boulardii stimulates the release of immunoglobulins (antibodies produced by white cells) and cytokines (small proteins released by the certain cells of immune system) where it promotes the maturation of the immune system.

This suggests that S. boulardii is able to activate our innate immune system and reduce the adhesion of pathogens in the body. S. boulardii can attach to the pathogens and neutralise their toxins. It is also suggested that S. boulardii has anti-inflammatory properties. If you struggle to find baker’s yeast you can use probiotic S. boulardii as an alternative. S. boulardii has been used in bread baking as an alternative to baker’s yeast (S. Cerevisiae) and it makes a great sourdough starter! Probiotic yeast can also be found in traditional culture starters to make kefir (a fermented dairy drink)!3

S. boulardii yeast can be ingested alongside other probiotics and a study suggests that supplementing of specific probiotic strains (L. acidophilus NCFM® and B. lactis Bi-07) can significantly reduce incidents of fever, rhinorrhoea and cough in children age 3-54.

These beneficial bacteria are an integral part of our immune system and it is important that we keep them in healthy balance to help strengthen, modulate and regulate our immune responses against various pathogens. The probiotics support the immune system in the fight against the virus, they don’t however directly inhibit the virus15.

Any alteration in microbiota can increase the risk of infection. L. acidophilus strains of beneficial bacteria can be found in fermented dairy products such as Kefir, Aaron, Chobani, miso or tempeh. B. lactis is used as a starter culture and therefore can be found in buttermilk, cheese and cottage cheese. You can also experiment at home with your own probiotic culture starter to make kefir! (freeze dried cultures starter can be purchased online).

Eat the rainbow – Although many of us associate this phrase with repeatedly trying to convince our children to eat a variety of fruit and veg, we sometimes forget that actually our immune system very much relies on it!

Colourful vegetables and fruits contain potent vitamins and minerals to help fight off infections. Vitamin C contributes to immune defence by supporting the innate and adaptive immune system. Vitamin C has an ability to accumulate in neutrophils (white blood cells) and control the cellular functions within the innate and adaptive immune system including microbial elimination. It also takes part in the removal and clearance of dead cells from sites of infection hence decreasing potential tissue damage. A prophylactic intake of 100–200 mg/day dietary vitC may reduce the chances of developing infection5. Research shows that people who regularly intake vitC have had milder symptoms of common colds. A higher dose is recommended to support the metabolic demands while an infection is already established (we lose vitC while we are fighting an infection). Elderly and individuals with vitC deficiency may have increased needs for vitC intake5.

It is recommended to incorporate fruits and vegetables rich in vitC regularly to avoid a shortage of vitC in the body. Foods rich in vitC include: green and red bell peppers, broccoli, Brussel sprouts, kale, papaya, strawberries and good old spuds! Try the classic Hungarian dish Lecsó made of a few very simple ingredients such as tomatoes, yellow and red peppers which are all rich in vitamin C!

Various plant pigments (flavonoids) found in colourful fruits and vegetables have antioxidant and safeguarding properties for the immune system. Rutin found in buckwheat, Japanese pagoda tree, green tea, figs and Eucalyptus, helps to strengthen and improve flexibility of our arteries and capillaries and supports the absorption of vitamin C in the body. Eating a couple of figs or a buckwheat noodle salad can help replenish your daily intake of Rutin.

Vitamin B12 – plays an essential role in our immunity by helping to increase the number of T lymphocytes (white blood cells) which are responsible for the optimal functioning of our immune system6.
B12 is mainly found in animal products such as lean meat, organ meats, fish (trout, salmon), eggs and dairy. B12 can also be found in green leafy vegetables7.

The National Institute of Health suggests that clams and beef liver have the highest amount of vitB128.

People who suffer from gastrointestinal issues (such as celiac disease), vegans or those over 50 are more likely to have vitB12 deficiency. If you are within that group, talk to your medical advisor or doctor about potential supplementation. It is recommended that vitB12 supplementation is taken with food to allow better absorption. Alcohol consumption can deplete B12 stores in the liver or make it more difficult to utilise it9.

Vitamin D – is able to regulate the innate and adaptive immune system in the fight against bacterial, viral and fungal infections. Studies suggest that a deficiency of vitD can be linked to increased susceptibility of infection. VitD is produced in the epidermal layer of our skin after exposure to sunlight.

Factors such as the season, latitude, skin pigment or sunscreen can influence how much vitD we synthesise in a day. Cholesterol in our body helps support the conversion of skin pigment melanin into vitD3 the most active form of vitamin D, which is then metabolised in our liver and kidneys and transported to our blood stream.

Great food sources of vitD are oily fish such as: salmon or mackerel, egg yolks, smaller amounts are also found in beef liver and fortified foods such as milk and dairy products. If you are unable to soak in the sun’s rays then supplementing with vitD3 can be a good way to ensure that we have a sufficient amount (make sure you consult with your health practitioner to discuss the appropriate dose for your needs).

Glutathione – a powerful antioxidant which has the ability to reduce oxidative damage and also contains anti-inflammatory properties.
Glutathione protects our immune cells from oxidative stress through its antioxidant properties and supports the optimal functioning of lymphocytes (white blood cells). It also inhibits inflammation in sites of pulmonary (lung) infection10.

Studies report that glutathione replenishment can be effective in antiviral treatment11. Glutatione is found in every cell of our body however due to chronic disease, prolonged stress and infections, its levels may become depleted. It is important we keep it topped up by eating sulphur rich vegetables such as cruciferous vegetables (broccolis, bok choi, kale, cabbage, Brussel sprouts) and sulphur rich proteins like poultry, fish and beef. The highest amount of glutathione can be found in avocados, spinach and asparagus (the UK season is fast approaching!) the latter two being the perfect accompaniment to a sulphur rich steak!

Zinc – Zinc plays a key role in our immune function, its intake stimulates the cellular functions of our innate immunity (e.g., phagocytosis by macrophages and neutrophils, natural killer cell activity, and the generation of oxidative burst). A deficiency of zinc can negatively affect the functions of our immune cells.

Some studies suggest that dietary intake or a supplementation of zinc may be helpful in decreasing the risk of pneumonia, the common cold and the severity of respiratory tract infections in the elderly and in children12. In two recent studies it has been highlighted that zinc may shorten the duration of common colds by 33% (57), however a daily dose of zinc still needs further investigation12.

Great sources of zinc include red meat, dairy, nuts i.e. brazil nuts, pumpkin seeds, chickpeas, lentils and whole grains.

Healthy gut – The gastrointestinal system plays an essential role in supporting the immune system. It can for example activate T-cells (type of white blood cells) through dendritic cells (messengers between innate and adaptive immune system) in the gut which are required for the immune defence against viral infections. It is estimated that approximately 70% of the immune function of the entire immune system is located in our gut!

Eating foods high in prebiotic carbohydrates (fibre) found in pulses, lentils, wholegrains such as oats, fibrous vegetables such as asparagus, green leafy vegetables, seeds and nuts promotes the growth and productivity of beneficial bacteria in our intestines. Try to increase your daily recommendation of fibre (30g) by snacking on nuts and seeds during the day or incorporating oats in your breakfast. Keeping our gut healthy helps to improve the immune response towards unwanted invaders and disease causing pathogens13.

Have a breather – These are truly unique times full of uncertainty however looking at the positives can help boost our immunity and wellbeing giving us the best chance to overcome a coronavirus or other pathogen nasties! Our emotional wellbeing may have a huge impact on our physical health. Research shows that when we are stressed our immune systems ability to fight off infections and antigens is weakened (for example our level of white blood cells is lower)14.

Focusing on a few things to help us tackle stress and addressing anxiety can pay off dividends over the long run. Managing emotions can be difficult, however little steps every day helps chip away and breaking down the achievable can become the building blocks to a bigger change:

• Get enough sleep
• Regular exercise
• Meditate and focus on deep breathing
• Mindfulness
• Reduce consumption of alcohol
• Allow for ‘me’ time

 To find out more about Magdalena’s work please visit


4. Leyer GJ, Li S, Mubasher ME, Reifer C, Ouwehand AC. Probiotic effects on cold and influenza-like symptom incidence and duration in children. Pediatrics. 2009 Aug;124(2): e172-9
15. Miyauchi K. Helper T Cell Responses to Respiratory Viruses in the Lung: Development, Virus Suppression, and Pathogenesis. Viral Immunol 2017;30:421-30



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