Plants that might help to protect you against COVID-19 can be found in your spice rack, garden and the hedgerows. Scientific research from SARS-CoV-1 found some familiar plants with antiviral powers.
During the lockdown period of the COVID-19 coronavirus outbreak, people with mild cases of the virus in the U.K. were told to self-isolate. Antiviral medicine that attempted to head off the virus was only prescribed in emergencies, on admission to hospital. Now, while I’m not claiming that plants are a sudden miracle cure, I do know that many plants are antiviral. After all, they’ve been doing chemistry for 400 million years and viruses have been around since the dawn of time. So I wondered if there was any evidence on the effectiveness and safety of plants, with coronavirus antiviral properties, that are commonly available to us all as herbs, spices and common garden or hedgerow plants.
In light of no other treatment available in the early stages, how can we best look after ourselves? It takes time to register new medicines and I fully appreciate that they need to be carefully tested and properly approved. However, what if the medicine is a commonly available food ingredient? If there are plants already used in home cooking, or that have been used for centuries as safe and simple medicines that can help to reduce viral load, surely we should all be told about them? Imagine if we could improve our own health, our family’s health and the community at large just by making sure the right range of vegetables was served up!
So I decided to take an organised approach to finding out…
Firstly I instigated a formal search procedure. The search engine PubMed provided by the US national Library of Medicine National Institute of Health was used to search for commonly used culinary herbs and spices for example: “garlic”, “cumin”, “citrus”, etc. or common fruit-bearing garden plants such as: “elder”, “saskatoon”, were entered into the search field plus the terms “AND coronavirus” and “AND COVID-19”. Journal papers cited in the results were accessed and read for relevance to the investigation.
I consulted herbals - of which I have a vast collection - to identify the names of antiviral candidates to submit to the search engines.
Just after lockdown was announced, the legendary Stephen Buhner (author of Herbal Antibiotics and Herbal Antivirals) published his thoughts on plants to use to keep fight coronavirus. Most of these I was also already using to treat my Lyme patients. So I also looked up all of Stephen’s suggestions too, although I am covering these in Part 2. (Many thanks, Stephen).
The following culinary herbs, spices, fruit-bearing garden plants and common hedgerow plants (also known as weeds) were found to have relevance.
Black cumin (Nigella sativa) also known as black seed is a common spice used in preparing Asian and Arabic dishes such as curries. The seed is used toasted, crushed and ground as a spice. An oil is pressed from the seed and used as a food supplement. Researchers Ulasli and team (2014) inoculated cells with mouse hepatitis virus–A59 to evaluate the effect of extract of a black cumin alcohol extract on the replication of coronavirus, and on the expression of TRP genes during coronavirus infection. Their equipment (ELISA kits) detected an increase in human inflammatory cytokine IL-8 levels for both 24 and 48 hour time points following treatment, and 6 TRP gene expression levels changed significantly after treatment. The virus load decreased when black cumin extract was added to the coronavirus infected cells. This spice is widely available.
I’ve taken to adding a spoonful of black seed oil into my salad dressings and onto my daily vegetable stir-fry.
Orange Peels Drying
Citrus fruits commonly used in the home include sweet orange (Citrus sinensis), tangerine (Citrus tangerina), lemon (Citrus limon), lime (Citrus aurantifolia) and grapefruit (Citrus paradisi). Hesperidin is a compound found in the fruits - its greatest concentration is in the peel. In Ulasli’s 2014 study, hesperidin was found to inhibit the ability of the coronavirus to replicate itself. The inference here is that as well as providing a high source of vitamin C - which helps our immune system defend us - that eating oranges and drinking orange juice can help protect us by being antiviral too.
I always buy organic. So I use a potato peeler to pare off all the rinds, before peeling the pith off the fruit or squeezing them. I then dry it and save it for adding into my herbal teas or grinding into a tasty zatar spice mix.
Chamomile is a popular herbal tea. Sold by a wide variety of companies, and in all mainstream supermarkets, chamomile tea bags are available in many homes. In 2014, Ulasli’s team also studied an Iranian chamomile (Anthemis hyalina). They found that using chamomile reduces the ability of the coronavirus to replicate itself. It was subject to the same in vitro experiment as the spice black cumin (Nigella sativa) and also increased IL-8 and changed levels of 6 TRP genes.
However, compared to black cumin and citrus peels, the chamomile extract showed the biggest decrease in virus load, leading to an undetectable virus load. In the chamomile family, the most commonly used for herbal teas in the U.K. are German chamomile (Matricaria recutita) and Roman chamomile (Anthemis nobilis). The main compounds in three different species of chamomile - including Iranian and German chamomiles - were analysed in laboratories (Jalali et al., 2008, Costescu et al., 2008). The three main sesquiterpene compounds were found to be in comparable levels in both species.
The U. S. Food and Drug Administration (FDA) have classified the oil and extract of German and Roman chamomiles as substances named as Generally Regarded As Safe (GRAS). So although further research needs to be done to see whether the antiviral compounds in chamomile survive into popular chamomile tea bags, nevertheless it is a herb that many of us already have at home!
Personally, I’m not a big fan of tea bags preferring loose tea instead. It’s higher in essential oils, stronger, just as easy (I use a single person cafetiere a.k.a. French press), properly compostable and doesn’t involve bleach, string or staples to make it.
At this time of year, a close relative is also making its appearance in the hard ground around farm gates and well trodden paths. This is pineappleweed (Matricaria discoides) a wild chamomile that also has many of the same properties. Pineappleweed can be picked and used fresh, or dried to make a loose tea. You just add hot water like any other tea. If you want a stronger decoction, just simmer it for 20 minutes and then leave it to stand for an hour or two. Then take smaller 50ml shots of it.
Fish mint (Houttuynia cordata) is a culinary mint used in Asian cooking, often regarded as an invasive species by British gardeners. Known as the ‘chameleon plant’ it is available from many garden centres and nurseries. It really should come with a warning as when it finds a nice place to live it spreads in very thick matts, crowding out local native species. The tender young shoots and leaves gathered in the spring are eaten raw or used as a pot-herb. The Japanese cultivar has an orange flavour and the Chinese cultivar has a coriander flavour.
Avian infectious bronchitis virus (IBV) is a positive-sense, single-stranded RNA virus that belongs to the coronaviruses. In an in vitro study confirmed by PDR testing, Yin et al. (2011) found that fish mint Houttuynia cordata inhibited the virus and decreased the apoptoptic rate by more than 90% (Mohajer Shojai et al., 2016). An ethyl acetate extract of fish mint was tested in an in vivo study against a murine coronavirus (Chiow et al., 2016). The researchers found that in Houttuynia cordata contributed to superior antiviral efficacy and lacked lacked cytotoxicity in vitro or acute toxicity in vivo concluding that it has much potential for the development of antiviral agents against coronavirus.
In addition to its antiviral potential, a water extract of Houttuynia was also found to increase CD4(+) and CD8(+) T lymphocyte cells, and increase IL-2 and IL-10 spleen lymphocytes in mice infected with SARS coronavirus (SARS-CoV) (Lau et al., 2008).
They found that it was highly antiviral against SARS-CoV coronavirus and non-toxic in laboratory animals. In 2003, 123 SARS cases in Beijing were followed (115 to discharge or death). Patients were treated with either a strictly western medicine (WM) treatment, or a combined treatment (WM plus an injection of Houttuynia cordata extract and other herbs where appropriate). The combined treatment approach resulted in a non-statistically significant mortality rate decrease (combined treatment: 9.6% versus WM: 11.1%) and significant improvements in arthralgia and myalgia and arterial oxyhemoglobin saturation (Li et al., 2006).
So perhaps research should be done to find out whether getting the nation to drink fish mint tea could help to provide antiviral protection by reducing the coronavirus COVID-19 viral load? Or perhaps it might improve symptom management alongside pharmaceutical medicines. And if you’re not fond of tea, it is lovely in a Thai curry!
A note of caution about fish mint. If you plant it do be aware it can quickly become invasive and out of hand. Rather like ground elder - another delicious edible weed - it can just take over. So put it into a big tub or a raised bed if you haven’t got a big garden.
In a study of chicken eggs infected with a coronavirus strain of avian infectious bronchitis virus (IBV), introducing a garlic extract 8 hours after the eggs had been inoculated with IBV had a significant inhibitory effect on the virus. Research should be undertaken to investigate whether increasing consumption of culinary garlic or taking a garlic supplement could help to inhibit infection by coronavirus COVID-19. Sure no one would benefit from making a huge profit on garlic, but if it’s a useful part of the culinary toolkit, why not? Perhaps we should crowd-fund research!
Black liquorice is available throughout the United Kingdom as a popular sweet and also as a herbal tea. Liquorice root contains glycyrrhizin that has been shown to inhibit SARS-CoV replication with a 50% effective concentration, further still several glycyrrhizin derivatives possess slightly higher antiviral bioactivity (Wu et al., 2004, Hoever et al., 2005).
My dad absolutely loved liquorice all-sorts but it took me a long time to appreciate them even though I loved the effect of black teeth! Liquorice root sticks are surprising sweet and tasty to chew on, and liquorice tea is widely available. Word of caution for liquorice lovers though… as with most things in nature don’t overdo it. Long-term use (e.g. 3 to 6 months) or high amounts of liquorice can raise your blood pressure. It also can make babies come early, so no liquorice gorging in pregnancy!
A study shown that an alcohol extract from the branches of Rosa nutkana was active against a bovine enteric coronavirus in vitro (McCutcheon et al., 1995). The extract inhibited the cytopathic effects of the virus. From British Columbia, the Nootka rose, in the family Rosaceae, is a wild rose closely related the British wild ‘dog rose’, Rosa canina. Rosehips of many Rosa species have traditionally been used by rural people to make a vitamin C rich syrup. Rose hips, petals and leaves (also a source of vitamin C) have also been used for centuries in herbal teas. The use of the branches is not a common tradition, however alcohol extracts of the flowers have been traditionally used as an anti-viral, anti-inflammatory, mildly sedative and mildly anodyne remedy for centuries (Bartram, 1998).
Roses? Who’d have known! Turkish delight anyone?
A study shown that an alcohol extract from the branches of Amelanchier alnifolia was active against a bovine enteric coronavirus in vitro (McCutcheon et al., 1995). The extract inhibited the cytopathic effects of the virus. Amelanchier, in the family Rosaceae, is an ornamental garden shrub known as the saskatoon or service-berry that produces an edible wild plum that ripens in June. Whilst it is the berry that was most commonly used as an aboriginal food, a decoction of the stems and bark of the branches was used by First Nation tribes as a folk remedy, to induce sweating in fevers, and in the treatment of influenza, lung infection and chest pain (Moerman, 1998).
This is a non-native shrubby, small tree that’s sometimes found in public parks as well. Urban foraging can get quite intercontinental sometimes! When you’re planning fruit trees in the garden or have space for a small orchard this is definitely one to consider.
Turmeric (Curcuma longa) is a popular spice used in the preparation of Asian dishes. Renowned for the anti-inflammatory phytocompound curcumin, it has also enjoyed recent popularity as a supplement and a drink (turmeric chai). Curcumin has shown mild activity against SARS-CoV replication and inhibition of 3CL protease (Wen et al., 2007).
That’s turmeric lattes all round then.
In the event of a pandemic, healthcare and hospital resources are stretched to the limit. Many people cannot be treated and many cannot also access pharmaceutical medicines due to self-isolation restrictions. Further research should be done to investigate the efficacy and safety of commonly used culinary and garden plants in order to provide information to the general public on the safe use of self-treatment measures that could improve public health and reduce hospital admissions.
References for all you boffins out there!
Bartram, T. (1998). Bartram’s Encylopedia of Herbal Medicine. London, UK: Robinson. ISBN 1-85487-586-8
Chiow, K. H., Phoon, M. C., Putti, T., Tan, B. K., & Chow, V. T. (2016). Evaluation of antiviral activities of Houttuynia cordata Thunb. extract, quercetin, quercetrin and cinanserin on murine coronavirus and dengue virus infection. Asian Pacific journal of tropical medicine, 9(1), 1–7.
Hedrick. U. P. (1972). Sturtevant's Edible Plants of the World. New York, NY: Dover Publications. ISBN 0-486-20459-6
Hoever, G., Baltina, L., Michaelis, M., Kondratenko, R., Baltina, L., Tolstikov, G.A., Doerr, H.W., Cinatl, J., Jr. (2005). Antiviral activity of glycyrrhizic acid derivatives against SARS-coronavirus. Journal of medicinal chemistry, 48, 1256-1259.
Jalali, Z., Sefidkon, F., Asareh, M.H., & Atar Farideh. (2008). Comparison of sesquiterpenes in the essential oils of Anthemis hyalina DC., Matricaria recutita L. and Matricaria aurea (Loefl.) Schultz-Bip. Iranian journal of medicinal and aromatic plants, 24(1), 31–37.
Lau, K. M., Lee, K. M., Koon, C. M., Cheung, C. S., Lau, C. P., Ho, H. M., Lee, M. Y., Au, S. W., Cheng, C. H., Lau, C. B., Tsui, S. K., Wan, D. C., Waye, M. M., Wong, K. B., Wong, C. K., Lam, C. W., Leung, P. C., & Fung, K. P. (2008). Immunomodulatory and anti-SARS activities of Houttuynia cordata. Journal of ethnopharmacology, 118(1), 79–85.
Li, S., Wang, R., Zhang, Y., Zhang, X., Layon, A.J., Li, Y., & Chen, M. (2006). Symptom combinations associated with outcome and therapeutic effects in a cohort of cases with SARS. The American journal of Chinese medicine, 34(6), 937-47. PubMed PMID: 17163583.
Moerman. D. (1998). Native American Ethnobotany. Oregon, OR: Timber Press. ISBN 0-88192-453-9
Mohajer Shojai, T., Ghalyanchi Langeroudi, A., Karimi, V., Barin, A., & Sadri, N. (2016). The effect of Allium sativum (Garlic) extract on infectious bronchitis virus in specific pathogen free embryonic egg. Avicenna journal of phytomedicine, 6(4), 458–267. PubMed PMID: 27516987
Rustaiyan, A., Masoudi, S., Ezatpour, L., Danaii, E., Taherkhani, M., & Aghajani, Z. (2011). Composition of the essential oils of Anthemis hyalina DC., Achillea nobilis L. and Cichorium intybus L. Three Asteraceae herbs growing wild in Iran. Journal of essential oil bearing plants, 14(4), 472–480. doi:10.1080/0972060x.2011.10643603
Ulasli, M., Gurses, S. A., Bayraktar, R., Yumrutas, O., Oztuzcu, S., Igci, M., Igci, Y. Z., Cakmak, E. A., & Arslan, A. (2014). The effects of Nigella sativa (Ns), Anthemis hyalina (Ah) and Citrus sinensis (Cs) extracts on the replication of coronavirus and the expression of TRP genes family. Molecular biology reports, 41(3), 1703–1711.
Wen, C.C., Kuo, Y.H., Jan, J.T., Liang, P.H., Wang, S.Y., Liu, H.G., Lee, C.K., Chang, S.T., Kuo, C.J., Lee, S.S., Hou, C.C., Hsiao, P.W., Chien, S.C., Shyur, L.F., & Yang, N.S. (2007). Specific plant terpenoids and lignoids possess potent antiviral activities against severe acute respiratory syndrome coronavirus. Journal of medicinal chemistry, 23, 50(17), 4087-95.
Wu, C.Y., Jan, J.T., Ma, S.H., Kuo, C.J., Juan, H.F., Cheng, Y.S., Hsu, H.H., Huang, H.C., Wu, D., Brik, A., Liang, F.S., Liu, R.S., Fang, J.M., Chen, S.T., Liang, P.H., & Wong, C.H. (2004). Small molecules targeting severe acute respiratory syndrome human coronavirus. Proc. Natl. Acad. Sci., 101, 10012-10017.
Yi O, Jovel EM, Towers GH, Wahbe TR, Cho D. (2007) Antioxidant and antimicrobial activities of native Rosa sp. from British Columbia, Canada. International journal of food science nutrition. 58(3), 178-89. PubMed PMID: 17514536.
Yin J, Li G, Li J, Yang Q, Ren X. (2011). In vitro and in vivo effects of Houttuynia cordata on infectious bronchitis virus. Avian pathology. 40(5), 491-8. doi: 10.1080/03079457.2011.605107.
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