Can plant phytonutrients grown in a controlled environment help people recover from Covid-19 and long Covid?

EatThis Functional Food

“First, do no harm” Hippocrates 

Covid-19 effects are the most well known in the world. More than a year on from the start of the pandemic and despite the roll out of effective vaccines in richer countries we still have a limited drug arsenal with worldwide coverage to make life easier for those most at risk. According to physicians at the Mayo clinic, the FDA have approved the antiviral drug Remdesivir and emergency use of the anti-inflammatory drug Baricitinib for use in patients hospitalised with COVID-19. In the UK Dexamethasone, an anti-inflammatory corticosteroids is authorised for use in severe cases. Studies found this drug reduces the risk of death by about 30% for people on ventilators and by 20% for people who need supplemental oxygen. But Dexamethasone and other corticosteroids may actually be harmful if given for less severe COVID-19 infections so it is reserved only for the critically ill. Clinical studies in the UK this year showed an additional benefit from the combination of two drugs used for rheumatoid arthritis, Tocilizumab and Sarilumab, which reduced the risk of mortality in ICU patients by 24%.  

The heart shaped stamen of Holy Basil – displays so many medicinal properties that it is known in Ayurvedic medicine as ‘The Elixir of Life’

Researchers across the world are examining the effects of anti-inflammatory drugs and other immunotherapies to suppress the virus. Controversial anti-malarial drugs were initially thought to control the virus but were quickly withdrawn by the FDA when data analysis showed that Hydroxychloroquine and Chloroquine were NOT effective for treating COVID-19 and can lead to serious heart problems. 

While the vaccines roll out across the world there is still the threat of COVID-19 variants lurking and developing in populations especially those geographies that have been unable to contain the virus. We now have increasing numbers of mutated spike protein variants of Covid-19 including the English Kent ( B117), South African (501.V2), Brazilian (B.1.1.248), Japan (P.1) and the Delta variant (B.1.617.2) causing concern as the virus continues to mutate and becomes more transmissible. This means we cannot be complacent and must keep searching for new ways to combat the disease whether through alterations of the vaccine or development of new drugs to reduce viral load. Of course this must be in tandem with continued social distancing, testing and isolation compliance with local laws to reduce the spread.

Epidemiologists writing in the journal Nature suggest Coronavirus is going to stay with us for some time. Then there’s the effect it leaves behind on our bodies, a new disease called Long Covid or as some in the US are calling it Long Haul Covid. Long covid is now defined by time post infection and acute long covid lasts 3 weeks whereas chronic long covid is ongoing for more than 12 weeks. The effects of long covid are wide ranging with some not even aware they have it, and symptoms include diarrhoea, nausea, vomiting and gastrointestinal pain. For those that recover from serious illness the effects can be life changing and far reaching including muscle loss, organ failure, reduced lung capacity, brain fog and even depression. 

Researchers are still learning how an infection with SARS-CoV-2 affects different parts of the body so new medicines can be developed. Although there is hope on the horizon with new antiviral drugs like TEMPOL and others in development we must remember the pathways of this disease are complex and still emerging. 

With this backdrop in mind we hope medicinal plant derived products that selectively block the ACE2 receptor may provide alternative ways to treat SARS-CoV-2. This blog is designed to be of interest to people with an interest in foods that can have a medicinal effect, growers who aim to produce unique medicinal crops and for scientists interested in the pharmaceutical properties of plants. 

Mechanism of cell entry and replication causing inflammation

We need to understand how the virus affects our bodies to know how to prevent dangerous physiological changes. Studies show the SARS-CoV-2 virus enters via epithelial and endothelial cells on the inner surface of blood vessels (see this 3D model of a blood vessel, spin it around as see the endothelial cells in purple on the inner wall) of both the large and small intestine and the respiratory tract using the angiotensin-converting enzyme 2 (ACE-2) as a binding protein. ACE-2 is embedded in cellular membranes and expressed in several critical tissues, including alveolar lung cells, gastrointestinal tissue and throughout the central nervous system. ACE-2 is important as it acts as a potent negative regulator of the renin angiotensin system (RAS) which controls blood pressure. Dr Craig Daly a vascular scientist from the University of Glasgow talks us through an easy to follow tutorial of the RAS pathway critical for maintaining homeostasis and controlling levels of the hormone angiotensin, which in turn controls blood pressure via constriction and dilation of blood vessels. 

When we are infected with coronavirus, the spike protein on the virus surface binds to ACE-2. Like a key in a lock the cell responds and encapsulates the virus pulling it inside to replicate its ribonucleic acid (RNA), creating a blueprint to potentially make 10-100 of virions that are subsequently released back into the bloodstream ready to infect more cells. 

After SARS-CoV-2 particles leave infected cells, there is a sudden release of inflammatory cytokines which results in leaking of fluid into alveolar sacs in the lungs. This is the ‘cytokine storm’ we hear so much about and this can be devastating if the viral load is too high as we have seen in healthcare workers at the beginning of the pandemic who were poorly equipped with PPE. Systemic inflammatory responses and multiple organ failure tragically cost the life of Dr Li in Wuhan in 2019, the medic who broke the news to the world. As we discovered in the early days, the lungs are unable to remove harmful gases like carbon dioxide and they cannot efficiently provide oxygen to the body. This helps the virus multiply rapidly in the lungs resulting in Acute respiratory distress syndrome

While respiratory symptoms are the most common sign of the disease, a recent review suggests 53% of people hospitalized with COVID-19 experience at least one gastrointestinal (GI) symptom during their illness. There is evidence that encountering GI symptoms with COVID-19, or developing them alongside underlying GI conditions like cardiovascular disease or diabetes can also increase the risk of disease severity. More recent research shows that the virus may alter the gut microbiota contributing to nausea and diarrhea. So all those memes of toilet roll are valid! The virus is then free to infect other targets like the central nervous system to cause further damage linked to neurological diseases resulting in long-lasting brain fog.

What natural plant extracts could potentiate some of these pathways?

Much of the latest research on plants used to fight covid symptoms and its after-effects originate from work in Asia and Thailand. It should be remembered that these plants need to be tested together and trials should be properly controlled as some extracts taken in excess or together can have detrimental outcomes. For instance peppermint and black teas can inhibit the absorption of iron, important in the transfer of oxygen to our tissues. So as we propose potential plants that exhibit beneficial effects at the sites of SARS-CoV-2 entry or may provide some inhibitory effects, it should be taken with a degree of optimistic caution in what may provide an alternative to pharmaceutical drugs. 

Physiological effects and mechanisms worth tackling with alternative plant based therapies:

  1. Fever control 
  2. Calming the cytokine storm 
  3. Prevention of viral shedding 
  4. Plants that control blood pressure through Angiotensin II or ACE
  5. Antagonising the SARs-CoV-2 spike protein
  6. Prevention of platelet aggregation
  7. Plant based nutrient balance of the renin angiotensin system
  8. Boosting the gut microbiome
  9. Antifungal activity to combat mucormycosis
  10. Diabetes regulation with plant phytonutrients from our previous article 
  11. Downstream brain fog with plant phytonutrients from our previous article 

Many plants display antiviral activity and we examine if these theoretically can provide a ‘super tea’ or emollient to reduce symptoms and help people recover from covid infections. Here we describe a few selected plants that are involved in trials (there are too many to provide a complete list but if you are interested reach out and we can discuss further) that could contribute to recovery from Coronavirus highlighting specific traits that potentiate the viral pathway. 

1. Plants that control fever

Andrographis paniculata has been used for hundreds of years in oriental and Ayurvedic medicine for a number of different ailments. The genus Andrographis belongs to the Acanthaceae family made up of around 40 different species. The plant is reported to possess wide ranging immunological, anti-bacterial, anti-inflammatory, anti-thrombotic and hepatoprotective properties. Phytochemical studies reveal a diverse range of compounds including diterpenoids like andrographolide, neoandrographolide and dehydroandrographolide. In India it is known as the Indian Echinacea where the aerial parts of the plant (leaves and stems) are still used in herbal medicines for flu and colds. It is also currently being used in Thailand for COVID-19 treatment of mild and moderate disease. Researchers purified the compound andrographolide which showed 99.9% inhibitory activity against the virus in cell cultures in the lab. 

Eucalyptus – alongside Frankincense and Lavender oils, Eucalyptus is classed as an essential oil that helps reduce significant fever. In the late 1800s, the ability to promote sweating and clear mucus led to eucalyptus oil being prescribed for respiratory conditions including bronchitis, flu, asthma, and coughs acting as a decongestant. Eucalyptus globulus leaves are distilled to extract the active oil Eucalyptol. But remember it is only recommended for topical application and must be diluted in a carrier oil like olive oil or it may burn or irritate the skin.

Eucalyptus in tissue culture from callus

Indian Frankincense comes from the Boswellia serrata tree, which is native to India, North Africa, and the Middle East. Farmers tap the tree to collect its resin. Boswellia resin and its active ingredient, boswellic acid, appear to have a good anti-inflammatory effect on the body according to a review article suggesting it has good antipyretic (reduces fever) activity.

Primordial leaves of Honeysuckle surrounding meristem studded with trichomes.

Japanese Honeysuckle is traditionally used for fever, sore throat, colds, flu and some infectious skin diseases. It is part of a combination of herbs called Yin Qiao San that was composed in the 18th Century when trade with the West brought new epidemic diseases to China. In China Qiao San was given to people with the initial symptoms of COVID-19 infection. 

In a 2018 review of the biological properties of honeysuckle, several studies demonstrated significant anti-bacterial, anti-viral, anti-inflammatory and antipyretic effects. Japanese honeysuckle was subsequently used in combination with other herbs and given to front line medical staff treating SARS in Beijing, none of which contracted SARS. Many Chinese provinces have issued preventative programmes using herbal medicines against COVID-19, and a review of the evidence suggests that people at high risk would probably benefit from taking CHM (Chinese Herbal Medicine) formula for prevention. This is now readily available in all Chinese  hospitals and pharmacies.

Hibiscus Among the medicinally active species is Hibiscus sabdariffa, the flowers of which are rich in phytonutrients and antioxidants like Vitamin C. One of the safest species for nutraceutical consumption, the hibiscus plant is made up of many plant acids, including citric acid, malic acid, tartaric acid and hibiscus acid which is unique to hibiscus.

There are many bioactive chemical constituents in Hibiscus including alkaloids, anthocyanins, and quercetin. With its high antioxidant levels, hibiscus reduces low-grade systemic inflammation when the lymphatic system is congested. Extracts of Hibiscus sabdariffa calyx were shown to have significant antipyretic activity in lab tests on fever induced in rats via a mechanism distinct from that of Aspirin. 

Extensive antihypertensive effects of Hibiscus have been widely reported and calyx extracts operate via vasorelaxant pathways of both endothelial cells and vascular smooth muscle cells, mediated through an increased production of nitric oxide.

2. Plants that calm the cytokine storm

Almost all plants will display some anti-inflammatory activity but here we pick out a few that have been studied extensively in peer reviewed journals and have relevance to COVID-19. 

Ashwagandha (Withania somnifera) also known as Indian Ginseng

Two independent research groups have discovered that Withaferin A (WFA), a steroidal lactone with anti-inflammatory and anti-tumorigenic properties, may bind to the viral spike protein of SARS-CoV-2 thereby blocking or reducing interactions with the host ACE2 receptor. WFA is also capable of reducing the secretion of various proinflammatory cytokines. One group has shown WFA does not alter expression of ACE2 in the lungs of tumor-bearing female mice. This is important as downregulation of ACE2 has recently been demonstrated to increase the severity of COVID-19 resulting from increased circulatory Angiotensin II levels through ACE (remember from the video tutorial this hormone increases blood pressure). So if  WFA does not downregulate ACE2 it has real potential as a therapeutic agent to treat or prevent the spread of COVID-19.

At least three independent research groups have suggested that phytochemicals found in Ashwagandha could be developed as a therapeutic agent against COVID-19 infection using molecular docking approaches.

Ashwagandha is from the solanacea family, related to tomatoes, eggplant and peppers. Unlike these relatives, there is no definitive evidence the fruiting berries are edible as they act as a strong emetic  (although temptingly beautiful above) and like ginseng it is the root after several years of growth that is valued most for powdered and gummy herbal remedies. It is NOT advised for pregnant and nursing women.

Sweet Wormwood (Artemisia Annua) grown from seed clean in tissue culture and then in  Aeroponics 

Researchers in the US have shown that extracts of Artemisia Annua with active compound Artemisinin, commonly known for its use as an anti malaria drug also has the ability to inhibit the replication of SARS-CoV-2. Both A. Annua and Artemisinin have been shown to reduce levels of the inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha in vivo. Early results suggest the active component in the extracts is likely something besides Artemisinin or is a combination of components acting synergistically to block post-entry viral infection. This area of research remains one of the most positive for fighting coronavirus cytokine effects. 

3. Plants that act as detergents preventing Viral shedding 

Butterfly Pea (Clitoria ternatea) is a holy flower in India used in daily puja rituals. The leaves are high in saponins known to act as a detergent which might be useful in removing the spike protein of Coronavirus. It may play an active role in viral shedding as the plant has been identified as a metalloproteinase inhibitor which could disrupt the process reducing the formation of virus. The metalloproteinase, ADAM17 involved in ACE shedding can be targeted using plants like Butterfly Pea as bio based surfactants. It has also been widely used in traditional medicines, and as a supplement to enhance cognitive functions and alleviate symptoms of numerous ailments including fever, inflammation, pain, and diabetes. Although the flower is widely used in teas and colour changing gins, both the seed and roots are not recommended (you can actually be fined in Taiwan for selling it as a foodstuff, butterfly pea is only used for minimal dye levels) as a food source due to much higher levels of saponins. It could however be highly useful as a natural soap based disinfectant in the fight against COVID-19.

4. Plants that control blood pressure through Angiotensin II and ACE

Various medicinal plants have shown inhibitory effects against Angiotensin II, many of which control blood pressure through this mechanism. Our previous EAT THIS blogs describe the actions of many plant based phytonutrients that have actions to reduce blood pressure. 

Image from Hydroponics Tips, Coriander in NFT

Coriander (Coriandrum sativum cilantro)

Coriander (Coriandrum sativum L.) was a traditional medicine for the treatment of cardiovascular and gastrointestinal diseases. Widely used by the Egyptians, coriander seeds were found alongside possessions of Tutankhamen when the tomb was excavated from the Valley of the Kings. It was a herb recommended by Hippocrates to treat inflammatory diseases and reduce blood pressure. In a 2013 study coriander oil was found to have strong potential as an ACE inhibitor. A few years later, 16 bioactive compounds extracted from coriander leaves were shown to exhibit significant ACE inhibition. Coriander and chlorella combined can remove heavy metals like mercury in the body in just a few months which helps people lose weight as it stimulates the pancreas to secrete insulin and lower blood sugar levels (reducing the risk category for serious COVID-19 illness). After some early concerns a study published by the British Heart Foundation has shown it is safe to use ACE inhibitors and Angiotensin receptor blockers to control blood pressure. 

Pomegranate (Punicagranatum Cassia) In Ancient Greece pomegranate represented fertility, eternity and good fortune and Hippocrates referred to its many medicinal properties including dampening inflammation and detoxifying. More recently pomegranate juice has been shown to have a competitive mode of action against coronavirus. Just a small cup of pomegranate juice can reduce ACE activity by 36% and lower systolic blood pressure by 5%. 

Pomegranate trees grown in Archangelos, Rhodes – medicine in your own backyard just as the Ancient Greeks would have done. Dr Li, a world renowned physician and scientist, describes how pomegranate promotes good bacteria in the gut, decreasing inflammation and lowering blood glucose levels. 

Pomegranate can be grown from seed in tissue culture to produce healthy clones. Dwarf varieties have potential for greenhouse production similar to blueberries

Holy Basil (Ocimum Sanctum) also known as Tulsi has been known to target the reverse transcriptase activity of HIV and theoretically could reduce activity of SARS-CoV-2. The leaves (main photo) contain Eugenol which is an effective treatment for high blood pressure. Just 100g of Basil provides 105% of Vitamin A and 30% of Vitamin C daily requirements. 

Garlic (Allium Sativum)

Anecdotal evidence from our Garlic blog just over a year ago suggests many people found the remedy to alleviate symptoms of covid. Garlic organosulfur compounds, allicin have many medicinal properties that could alleviate Covid 19 symptoms and evidence suggests it can not only  target the viral replication of SARS-CoV-2 but also inhibit ACE activity to dampen Ang II-induced vasoconstrictor responses in blood vessels.

Galangal  (Boesenbergia rotunda) High throughput fluorescence screening of plants in a trial in Thailand has picked up activity of a phytonutrient in galangal called Panduratin A acting as an anti-SARS-CoV-2 agent preventing entry to human airway epithelial cells in the lab. The Nature article concludes the purified compound, Panduratin A has a potent inhibitory effect against SARS-CoV-2 replication and infectivity with the favorable cytotoxicity profile. Interestingly, panduratin A inhibited SARS-CoV-2 infectivity and replication at both pre-entry and post-infection phases, and its antiviral activity was even more potent than hydroxychloroquine. Related to the ginger and turmeric zingiberaceae family this shows promising therapeutic value in the fight against Coronavirus. Studies of curcumin on antiviral activity also show promise. See our previous articles on growing these plants in a controlled environment.

Boesenbergia Rotunda in tissue culture courtesy of Mike Wallace.

5. Antagonising the spike protein

A study last year found that curcumin, nimbin, withaferin A, piperine, mangiferin, thebaine, berberine, and andrographolide have significant binding affinity towards spike glycoprotein of SARS-CoV-2 suggesting they could provide a route to prevent cellular infection. 

Neem (Azadirachta Indica) Nimbin extract from Neem is known for its antibacterial properties but molecular docking studies have also proved extracts could have inhibitory activity on the Papain like protease of SARS-CoV-2. Neem extracts have been well documented including inhibitory action against viral activity of herpes, smallpox, chickenpox, HIV.

Self heal (Prunella vulgaris) in Tissue Culture

Researchers in Canada have shown mutations in the SARS-CoV-2 spike protein increases its incorporation into cells leading to increased viral load causing significantly higher transmission rate in infected individuals, but thankfully there has been no reported significant change in disease severity. Self heal contains a compound, suramin, which displays potent inhibitory effects on the spike glycoprotein in an in vitro model cell system. This could prove to be a crucial breakthrough against variants that are more infectious, particularly if these compounds can be manufactured as a nasal spray. 

Licorice (Glycyrrhiza glabra L.) Licorice is a plant of the climbing  pea family containing the natural sweetener glycyrrhizin in the root which is over 50 times sweeter than sucrose. Scientists have known for some time that glycyrrhizin improves defences against viral infections, particularly rotavirus which invades the intestines leading to diarrhoea. Indeed glycyrrhizin increases the body’s ability to shed rotavirus by 50% in the lab, a process thought to operate through recruitment of T cells which help reduce infection. A German group demonstrated that glycyrrhizin, the primary active ingredient of the licorice root, potently neutralizes SARS-CoV-2 by inhibiting the main viral protease. These experiments highlight glycyrrhizin as a potential antiviral compound that should be further investigated for the treatment of COVID-19. 

Licorice prefers its roots to be wet and researchers at Chiba university in Japan developed a pressurised hydroponic system to produce reliable root mass in half the time it would take to grow wild. But you should consume Licorice in moderation as it can interfere with sodium and potassium levels which can lead to increased blood pressure. A Licorice tea every few days is ideal. 

Licorice in tissue culture

6. Plants that inhibit platelet aggregation

SARS-CoV-2 and its spike protein directly stimulate platelets to facilitate the release of coagulation factors, the secretion of inflammatory factors, and the formation of leukocyte–platelet aggregates. Although platelet activation is critical for thrombosis and is responsible for the thrombotic events and cardiovascular complications, the role of platelets in the pathogenesis of COVID-19 remains unclear. Critically ill patients diagnosed with COVID-19 may develop a prothrombotic state that places them at a dramatically increased lethal risk so it is important to find ways to inhibit the process. 

Wasabi Japonica is prone to many diseases but clean stock plants can be initiated in tissue culture by ‘The Functional Plant Company’.

Platelet aggregation was first associated with COVID-19 in patients in Wuhan, China as infection produces a prominent elevation of fibrinogen and D-dimer/fibrin degradation products. The damage is caused by the immune system going on the attack (cytokine storm), damaging blood vessel walls and removing several of the normal anti-clotting mechanisms. Essentially the virus causes damage to the lining of blood vessel walls increasing systemic hypercoagulability and blood clots are more likely to form. The degree of D-dimer elevation positively correlates with mortality in COVID-19 patients.  

We have previously described the wide range of medicinal properties, anti-microbial, anti-diabetic, anti-asthmatic, anti-cancer, antiviral and anti-fungal in Wasabi Japonica. The active glucosinolate, 6-methylsulfinylhexyl isothiocyanate (6-MSITC) found predominantly in the swollen stem or rhizome of Wasabi as a potential inhibitor of human platelet aggregation in vitro.   

Wasabi ITCs are effective agents for inflammation based on their rapid action and the low levels needed. Isothiocyanates of Wasabi and other crucifers like watercress and broccoli are anti-inflammatory and anti-asthmatic and may provide ease of SARS-CoV-2 symptoms. 

7. Plants can increase essential nutrient levels boosting immunity

Vitamins play a vital role in immune function. 

Patients with severe Covid-19 are reported to be low in both iron and Vitamin D levels and associated with severe acute respiratory disease. These groups include the elderly, people living in the northern hemisphere, obese adults and darker skinned people who produce significantly less Vitamin D and are more likely to be anaemic than other groups.

Low levels of Vitamin D3 actually inhibit renin. Less renin production tips the equilibrium in favour of more Angiotensin II, subsequently raising blood pressure.

Cholecalciferol (Vitamin D3) is a prohormone nutrient synthesised from meat retrieved cholesterol and is processed in the liver using iron as a cofactor for activation.  With increased levels of Vitamin D the expression of proinflammatory cytokines that induce production of C-reactive protein can be significantly diminished

There are now calls to supplement daily diets with 1000-2000IU/day Vit D3 to lessen the severity of COVID-19. Vitamin D3 is not a cure for covid-19 but it does have global significance if studies suggest 30-50% of the world’s population are deficient. A study in 2020 showed that a Vitamin D3 blood level of at least 75 nmol/L is needed for protection against COVID-19. An adult needs 4000 IU/day of Vitamin D3 for 3 months to reliably achieve a 75 nmol/L level. People with darker skin need twice as much Vitamin D3 as they produce more melanin which blocks UVB rays and inhibits production of Vitamin D. These doses can greatly reduce the risk of severe illness, but this is not enough for treatment of acute viral infection, which requires a 60,000 to 120,000 IU dose intervention.

Moringa oleifera also known as the miracle tree due to its multiple medicinal uses. It is a fast growing, drought resistant plant that reaches full maturity in less than a year and although we don’t know of anyone growing in a commercial controlled environment we believe it is theoretically possible. It is one of the most nutrient dense plants in the world containing a high abundance of vitamins. Moringa has an impressive range of anti-Inflammatory, anti-viral, anti-fungal, antidepressant activity and cardiovascular protective effects.

Vitamin A plays a vital role in strengthening the immune system, protecting us against common infections such as flu by maintaining healthy mucus linings inside the nose and the lungs. 

Moringa leaves are a fantastic source of protein and high in plant based non heme iron and antioxidants. Consuming just 10g of moringa powder a day for 3 months can significantly increase levels of iron, antioxidants and Vitamins A and C in the bloodstream. Vitamin A is normally found in dairy, eggs and oily fish but also in some leafy greens and is essential for iron metabolism. Moringa contains four times the amount of Vitamin A (also known as retinol) as carrots, the vegetable we naturally think is the best for our eyesight as it produces important pigments for eye retina health. Pregnant women should be cautious about supplemental Vitamin A and intake only through a balanced diet is recommended. 

Remember that yellow, red and green fruits and vegetables contain beta and alpha carotenoids, lutein, lycopene, zeaxanthin, astaxanthin, β-cryptoxanthin which act as a precursor to Vitamin A. 

Can a plant based diet provide an adequate source of Iron? 

We traditionally consume heme iron from meat, poultry and seafood sources whereas non-heme iron is found in plant foods like whole grains, nuts, seeds, legumes, and leafy greens. Over 79 million people around the world are vegan and don’t eat either meat or dairy products. It was always thought vegans could be deficient in iron due to low absorption of nutrients as our diets change and we move to healthier plant based diets. 

Why is this important? Well heme Iron is absorbed more easily than non heme iron and stored in the body as ferritin, it acts as a cofactor in our blood cells and essential for the uptake of oxygen. We know that SARS-CoV-2 patients have low iron levels which exacerbates oxygen levels to the lungs. 

Some eminent physicians suggest the latter plant based non heme source is adequate for all our iron requirements as we also consume more Vitamin A, C and E from plants which aids non heme iron absorption. Infact, Dr Greger presents data that shows too much heme iron cannot be processed by the body and leads to pro-inflammatory diseases like diabetes and Chronic heart disease.

Life saving high dose Vitamin C

It is becoming clear that high blood levels of not just Vitamin D3 but also Vitamin C are needed to prevent COVID-19 deaths.

Infection triggers a severe inflammatory cellular reaction in the body which results in a decrease in Vitamin C. Along the evolutionary timeline 40 million years ago we lost the ability to make Vitamin C in our bodies due to a genetic mutation.

Unlike most mammals we are unable to synthesize Vitamin C endogenously ourselves so we must access it from our diet. Vitamin C plays an important role in immune function and improves the absorption of nonheme iron, the form of iron present in plant-based foods. It is well understood that insufficient Vitamin C causes scurvy, which is characterized by fatigue. We all know that sailors used a variety of citrus fruits to prevent scurvy but in Scotland where citrus fruits were not abundant they foraged Rock Samphire on the west coast as they found the leaves were high in Vitamin C. Today Rock Samphire is located in only a few inaccessible cliffs but it has potential as a CEA crop.

Rock Samphire – Sea Fennel in tissue Culture 

The plant is not well used in herbal medicine as it can be so hard to access but if you can find it then it’s very useful as a herbal tea. It contains Vitamin C (ascorbic acid and dehydroascorbic acid), polyacetylenes (falcarinol and falcarindiol), flavonoids (diosmin), furanocoumarins, pectin, and minerals. Falcarinon, acts as a natural antibiotic and has a positive effect on the digestive tract. 

Kumquat Yuzu (hybrid)

Hesperidin and ascorbic acid in Yuzu counteract the cell damaging effects of the oxygen free radicals triggered by viral infections and inflammation. There is discussion about the preventive efficacy of Vitamin C, at the dose achievable by the diet, as recent reviews suggest it can be useful in the case of strong immune system burden caused by viral disease. 

Today we can access many exotic dried fruits from around the world that are high in Vitamin C including Acerola, Schisandra and Goji berries. Read more about them in our previous EAT THIS articles. Just keep eating those berries! 

8. Plants that boost the gut microbiome 

Associations between gut microbiota composition, levels of cytokines and inflammatory markers in patients with COVID-19 suggest that the gut microbiome is involved in the magnitude of COVID-19 severity possibly via modulating host immune responses. This change in gut microbiota dysbiosis post disease could contribute to Long haul covid, highlighting a need to understand how gut microorganisms are involved in inflammation and COVID-19. I have picked out two I grow in controlled environments but there are many fruits and vegetables that act as probiotics (boost gut commensal bacteria) and prebiotic (feed the bacteria).

Chinese Yam

Chinese yam or air potato increases beneficial Lactobacillus bacteria which is thought to be disrupted following SARS-CoV-2 infection. However, Chinese yam is an invasive species in the United States. Multiple states, including Michigan, have active control programs whereby the government asks citizens to report sightings of Chinese yam. As with water yam, Chinese yam grows well in aeroponic CEA reducing the risk where they can be monitored and controlled. 

Kiwi in Tissue Culture, dwarf varieties in CEA have potential 

Kiwifruit affects intestinal microbiota populations, namely Lactobacillus, Bacteroides, Clostridium, Bifidobacterium, and Enterococcus. Studies have shown Kiwifruit is a prebiotic selectively enhancing the growth of intestinal lactic acid bacteria, promoting the content of faecal lactobacilli and bifidobacteria. Since 2015 there has been a shift towards growing kiwifruit in New Zealand in high poly tunnels with drip irrigation to protect them from disease.  It is not just the human population that is suffering from increased viral infections, many intensively farmed crops also have viral threats. 

A meta-analysis (data gathered across many clinical studies) in 2020 found that more than half of Covid-19 patients had received antibiotics despite only 7% presenting with a bacterial infection. It suggests the use of antibiotics may accelerate the damage to anti-inflammatory promoting bacteria in the gut. The probiotic effect of kiwifruit is transient so you must keep eating those juicy fruits.

9. Antifungal activity to combat mucormycosis

Mucormycosis is a serious but rare fungal infection caused by a group of molds called mucormycetes that commonly affects the sinuses or the lungs after inhaling fungal spores from the air. It is caused by exposure to mucor mould which is commonly found in soil, plants, manure, and decaying fruits and vegetables. Increased occurrence of mucormycosis in COVID-19 patients in India is being reported. They require antifungal treatments including liposomal amphotericin B injections but these may lead to side effects. There are many plants with antifungal properties, in fact most of those we describe in this article will have potency against fungal spores. The most accessible include garlic, turmeric and ginger but they should be taken as supplements if fungal disease is suspected. 

Unexpected positive side effects of Covid

Forbes reported on a case in the U.K. of a 61 year old man with aggressive non hodgkin’s Lymphoma going into full remission after contracting COVID-19. While this is an isolated case it gives huge insight into the mechanisms of blood cancer processes and a future opportunity of study. This will undoubtedly lead to understanding new mechanisms linked to cytokine release and the body’s own immune reactions. 

The molecular mechanism by which these medicinal plants target influenza virus can be studied to understand if they attack any molecules overlapping between SARS-CoV-2 and the Influenza viruses. Himalayan forests are abundantly rich in medicinal plant species and a study has documented the presence of ethnomedicinal plants against bronchitis caused by influenza virus, rhinovirus, adenovirus, coronavirus and respiratory syncytial virus.

With emerging Coronavirus variants, there is concern they cannot be quickly and efficiently eliminated in populations across the world leaving us all vulnerable to future pandemics,  or more likely localised epidemics. Regardless, we should be ready and working towards multiple strategies to combat outbreaks and plant biochemistry can play a part if we have peer reviewed studies initiated now. 

Growing plants in Controlled Environment Agriculture

Many if not all these plants can be grown in some form of controlled environment whether it be hydroponics or initiated as clean clones using plant micropropagation. Adapting farms to grow medicinal plants is not difficult and most of these plants will grow in a pH range 6-6.5 with EC 1-1.5 and suitable substrates. The question remains if there is an outlet for this kind of opportunity. That is up to our readers, farmers, growers and academics to address. We have previously discussed many plants that contain phytonutrients and how these can be manipulated using tailored light spectrum and intensity in a clean controlled space which is essential if these plants are to be scaled up for industrial extraction. Consumers should be reassured by these plants being grown in a pesticide and fungicide free environment.  

SUPER TEAS and DETERGENTS – Natural Remedy. 

To summarise, the plants we have selected have the potential to make a ‘super tea’ with active ingredients including isothiocyanate (Wasabi), glycyrrhizin (licorice), quercetin (Hibiscus), eugenol (Holy Basil) suramin (Self heal), hesperidin (Yuzu), ascorbic acid (Samphire), artemisinin-purified and approved (Sweet Wormwood), curcumin (turmeric), withaferin A (Ashwagandha), piperine (black pepper), mangiferin (honeybush), thebaine (poppy), berberine (European barberry, goldenseal, goldthread, greater celandine, Oregon grape, phellodendron and tree turmeric), panduratin A (Galangal), allicin (garlic) and andrographolide (Andrographis). Clear evidence of supplemental Vitamin A, C and D3 supports documented research to reduce Covid-19 disease severity. Emollients made with eucalyptus, Neem, lavender, and frankincense along with nasal sprays incorporating self heal or butterfly pea soaps have potential to provide added protection against coronavirus infections. 

Having read this you may now be wondering, where do I get hold of these wonderful medicinal plants? So at this juncture I urge a little caution, many medicinal plants are available individually as dried root or tea preparations but please ensure you check they are from a reliable and validated source. Combinations can increase efficacy so check this out with your local Chinese herbalist who can advise on TCM. It is best to take professional advice before trying any plant based remedy.

We anticipate CEA farmers or even pharmacologists will want to grow these plants in the future.  If you have an interest in this we would love to engage with you as we have experience of growing a wide range of plants in a controlled environment to produce the highest quality for either study or scaling. Please reach out and consider working with us. 

I am indebted to my friend and colleague UAN & Hort America’s founder and owner Chris Higgins. Without his knowledge, support and encouragement, my entrepreneurial work would not be possible. I am grateful to my friends, physician Dr Barbara Scott MD, Veterinary Lecturer Dr Sally Anne Argyle MRCVS, cardiovascular scientist Dr Craig Daly SFHEA, and Jenny Sim LLP, for their time in reviewing this article. Hort Americas has a full resource and knowledge bank to get you set up growing any of these plants in a controlled environment. 

Disclaimer: We are not advocating this information in preference to medical advice, remember if you have serious illness and symptoms of Coronavirus or Long Covid please seek advice from your general practitioner. Our blogs are designed for people looking for advice on plants that have additional phytonutrients that can help repair the body and boost the immune system. We advise you to stay within peer reviewed research and CDC guidance. 

Unless otherwise stated all images are from plants grown using TC or in CEA by The Functional Plant Company in Scotland and images are the property of Urban Ag News. You can follow The Functional Plant Company on Instagram.The authors declare no affiliation to any companies offering herbal remedies and the information provided is a scientific peer reviewed compilation of plants that provide an opinion of the best potential inhibition of critical pathways involved in SARS-CoV-2 infections. 


Janet Colston PhD is a pharmacologist with an interest in growing ‘functional’ foods that have additional phytonutrients and display medicinal qualities that are beneficial to human health. She grows these using a range of techniques including plant tissue micropropagation and controlled environmental agriculture to ensure the highest quality control.

2 thoughts on “Can plant phytonutrients grown in a controlled environment help people recover from Covid-19 and long Covid?

  1. Thanks for this wealth of info on medicinal plants. We are seeing a trend at our Garden Center towards this homegrown sustainable method of gardening. Backyard greenhouses being their medicine cabinet is on the rise.

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