There is a word more and more popular in science communication circles: pre-bunking. There is so much bunk out there—misinformation, lies and unwarranted hype—that it always feels like we are playing catch-up. The idea of pre-bunking is to get in front of the bunk and warn people in advance so they can recognize the signs of rubbish when they see them. A sort of vaccine for the mind, if you will.
So consider this a bit of pre-bunking. A few days ago, a scientific paper was published that reported on laboratory work done with the leaves of the Ginkgo biloba tree. To be abundantly generous, the work shows very early promise for the possible development of new anti-COVID-19 medications. The study will undoubtedly be used as validation for supplement pushers: taking ginkgo pills, they will say, is an all-natural way to effectively treat or even prevent COVID-19 (and, of course, this knowledge is being suppressed by the pharmaceutical industry). This is not what this study shows by a long shot.
Ginkgo biloba is the name of the oldest tree species in the world. Extracts made from its leaves are often touted as a cure-all. This new paper even mentions that these leaves are “widely applied for preventing and treating a variety of human diseases, including cardiovascular disorders, pulmonary disease, and central nervous system diseases.” Of course, its popularity is no gauge of its efficacy. Ginkgo is commonly sold to help with memory or attention problems but the scientific evidence is “inconsistent and unreliable.” Small, poorly designed studies will do that. The National Center for Complementary and Integrative Health judges that there is “no conclusive evidence that ginkgo is helpful for any health condition.”
On the heels of an earlier article commenting about the potential for Ginkgo biloba to be tested against the SARS-CoV-2 coronavirus, we now have some data from this recent paper, but it is a far cry from proof that ginkgo can be ingested by humans to treat COVID-19.
The researchers screened 80 herbal products, including ginkgo. They tested each of them in the lab against an important part of the SARS-CoV-2 virus, a molecule called 3-Chymotrypsin-like protease. They reported that the extract from ginkgo, out of the 80 products they tested, was the best at inhibiting the activity of this protease the virus needs to make copies of itself. While they focused on ginkgo, it’s important to point out that other herbal products also had a similar effect on the protease: Chinese goldthread, common knotgrass and loquat, among others. Because plants can contain many different molecules, they tested different groups of molecules contained in the ginkgo leaf extract and reported that the best ones were the bioflavones and the ginkgolic acids. So what do we make of this?
The word “potential” cannot be repeated often enough
The authors contextualize their findings with two critical quotes. The first one illustrates the long, arduous and often disappointing path that early findings in the lab must take to make their way into our pharmacies. “Although a wide range of phytochemicals [chemicals extracted from plants] and synthetic molecules have been reported with anti-3-Chymotrypsin-like protease activity,” the authors write, molecules that fit the bill and that have “high potency and favorable safety profiles are rarely reported.” It’s much easier to prevent a virus from making copies of itself in the lab; it is much, much harder to ensure this compound will be good enough and safe enough in the human body. We are not giant Petri dishes.
And about those miraculous Ginkgo bioflavones that were so good at gumming up the works of the coronavirus in the lab, the authors point out that most bioflavones found in nature don’t go through our membranes easily (an important feature if they are to be absorbed by the body), they have poor solubility, and the amount that reaches our blood circulation is “extremely poor.” And those ginkgolic acids mentioned earlier? They have strong toxicity and can cause severe allergic reactions. The authors are not arguing for the use of ginkgo leaf extract in patients with COVID-19; they are instead suggesting that these ginkgo molecules could potentially be “extensively modified” in the laboratory to generate new treatments against COVID-19. Potentially.
In scientific history, the development of antivirals—drugs that interfere with a virus’ ability to make copies of itself—has been especially challenging. Anti-HIV medication remains an exceptional success story. Basic research like this paper on Ginkgo biloba can inspire further research, but we can’t skip over this lengthy process just because ginkgo is natural and readily available. Molecules made by Mother Nature are not inherently safe. Extracts from the leaves of the Ginkgo tree can interfere with other drugs and cause bleeding, nausea, heart palpitations, and other symptoms, and its ginkgolic acids, as previously mentioned, can provoke severe allergic reactions.
And when it comes to Ginkgo biloba extract being sold as a natural health product, the refrain remains the same: who knows what’s inside if it’s “natural?” A recent report by the Office of the Auditor General of Canada on Health Canada’s oversight of natural health products characterized this oversight as “[falling] short of ensuring they were safe and effective.” Contamination and adulteration abound in this space, and Health Canada does not have the authority to force a recall for any reason, even for serious risk of death.
In short, a laboratory study showed that some molecules found in the tree Ginkgo biloba (and other plants as well) can hinder an important molecule the SARS-CoV-2 coronavirus uses to make copies of itself. This study alone should never be used to justify selling ginkgo supplements as a cure for COVID-19.
-Extracts from the leaves of the Ginkgo biloba tree are often sold as cure-alls but there is no conclusive evidence they work to treat any condition.
-A recent study found that some of the ingredients contained in the leaves of the ginkgo tree can interfere with a molecule the SARS-CoV-2 coronavirus needs to make copies of itself
-This study absolutely does not demonstrate that ginkgo can be used to treat or prevent COVID-19