How chlorogenic acid protects coffee drinkers against Covid-19
Coffee may protect against the virus that causes Covid-19. British-American epidemiological research suggests this. If this is true, then thanks to research from the China Medical University in Taiwan, we understand how. And which substances in coffee exactly provide protection.
In 2021, epidemiologists from Northwestern University in the United States published a study into the link between diet and the risk of Covid-19. [Nutrients. 2021 Jun 20;13(6):2114.] Their research was based on data collected in the UK's UK Biobank project.
The strongest connection that the Americans were able to extract from the British data was the link between coffee and the risk of disease. Those who drank 2 cups of coffee or more daily had an 8-9 percent lower risk of Covid. The table below tells you this.
Click on the table for a larger version.
Biologists from China Medical University in Taiwan wanted to know more about the exact way in which coffee can protect against the still circulating and ever-mutating SARS-CoV-2. So they had test subjects drink coffee, took a little blood and experimented with that blood.
The researchers introduced home-made virus-like particles - pseudoviruses - into their blood samples. They had attached spike proteins from SARS-CoV-2 to the pseudoviruses. They then looked to see whether the pseudoviruses could infect mock cells.
These fake cells had human ACE-2 receptors. The virus uses the ACE-2-receptor to slip into cells. After infection, the mock cells emit light. The more light they emit, the more frequently they are infected.
The pseudoviruses were less able to infect fake cells when the test was carried out in a blood sample from test subjects who had drunk 1-2 cups of coffee. The figure below relates to experiments that the researchers conducted with pseudoviruses to which they had attached a spike protein from an early omicron variant.
The viral inhibitory effect was present 4-6 hours after the subjects drank their coffee - but no longer after 24 hours. The figure above tells us that.
The researchers also conducted their experiments with pseudoviruses that had received the spike protein from other SARS-CoV-2 viruses. Coffee also sabotaged those variants. The researchers also conducted tests in which subjects drank coffee without caffeine. Even without the stimulant, coffee protected.
Based on in vitro studies, the researchers suspect that chlorogenic acids in coffee sabotage the functioning of the spike protein of the virus. In most of the active fractions that they were able to extract from coffee, they mainly found the isochlorogenic acids isoCGA-A, isoCGA-B and isoCGA-C.
According to computer models, those compounds could indeed stick to critical parts of the spike protein, causing the darn thing to no longer work properly.
The researchers conducted in vitro studies, the results of which suggest that isochlorogenic acids inhibit the interaction of the spike protein with the ACE-2 receptor and sabotage TMPRSS2 and L-cathepsin in human cells. The currently dominant SARS-CoV-2 variant uses the ACE-2 receptor and TMPRSS2 to enter human cells and L-cathepsin to replicate within cells.
"Our human trial study suggested that drinking coffee (approximately 1-2 cups per day) has a potentiated ability to suppress the infection with present SARS-CoV-2 strains", the researchers summarize.
"Based on the results, we [...] suggest a coffee-drinking plan for people to prevent infection in the post-COVID-19 era."
Cell Biosci. 2023 Nov 14;13(1):210.
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