Thyme, ginger, honey or herbal teas… everyone has their grandmother’s secret to relieve flu symptoms. But what exactly does science say about the effectiveness of these natural remedies against COVID-19?
“There are a lot of things for which we see anti-inflammatory, anti-infective effects, but in vitro, in animal cell models,” explains Sylvie Dodin, clinical researcher at the CHU de Québec and specialist in non-drug approaches. “Transferring to humans is so complicated, because there are so many interactions. »
Thus, studies that prove that natural treatments relieve “flu symptoms” suffer from several biases. Between the common cold and COVID-19 unfolds a myriad of symptoms, and often these ailments subside on their own from one day to the next, blurring the establishment of a clear link between a product and the end of the symptoms.
And above all, no study directly addresses the issue of COVID-19.
Nevertheless, there are “little scientific evidence” concerning three products capable of relieving the sick, indicates Sylvie Dodin.
Zinc, first, “seems to reduce the duration of symptoms by a day and a half”, according to a systematic review of the literature. On the other hand, this supplement causes unpleasant nausea-like side effects.
Then, honey has demonstrated its antiseptic properties in three “average quality” clinical studies, notes Ms. Dodin. The harmlessness of this sweet syrup makes it a natural product of choice.
Finally, echinacea extracts “also appear to decrease the duration of symptoms”, according to a meta-analysis of studies on the subject.
For the rest, the placebo effect can explain many remissions. “The placebo effect can be as high as 30%,” points out Ms. Dodin. For a natural product to be declared effective, it must therefore relieve even more than this placebo effect. “A herbal tea is comforting, but is it better than a cup of hot water? »
As the adage repeated by Mrs. Dodin goes: “Without treatment, the flu lasts seven days. With treatment, the flu lasts a week. »
Prevention rather than cure
However, Quebec researchers have identified a “kind” of vitamin that would prevent infection altogether.
Professor Nabil Seidah, laboratory director at the Montreal Clinical Research Institute, tells Le Devoir that he “found quite unexpectedly” that swallowing a gram of L-carnitine every day “reduces the risk that the virus will infects”.
According to his team’s recently published study, when this molecule of L-carnitine (an animal by-product) enters human cells, it “significantly decreases the number of ACE2 receptors” on the surface of said cells. ACE2 receptors act as an entry point for the virus into our cells.
L-carnitine “enters the cell and asks the cell to synthesize less of this receptor”, explains Nabil Seidah. ” [La molécule] decreases the number of surface receptors and decreases the risk of the virus infecting you. »
The logic of this study implies that this preventive remedy could apply to other coronaviruses, because “most coronaviruses have an ACE2, but this is not always the case”.
L-carnitine “is sold everywhere, in the aisle of organic products”, says Mr. Seidah.
This text is taken from our newsletter “Coronavirus mail” of March 28, 2022. To subscribe, click here.