Most supplements that are talked about amid the coronavirus outbreak are either essential nutrients or immune boosters. So what does a polyphenol from red wine have to do with the current health crisis? Read on for some surprising new resveratrol research.
This article is for informational purposes only. The current coronavirus outbreak is an ongoing event and certain details may change as new information comes to light.
Resveratrol Research Amid the COVID-19 Health Crisis
A recent comment in the prestigious journal Nature stresses how urgently we need medicines for the current coronavirus outbreak [1].
But if you think that only immune-stimulants, antivirals, and essential nutrients are being researched against the new coronavirus, you’re in for a surprise.
Scientists behind the commentary list all potentially promising compounds that might either help kill the new virus or prompt our immune system to get rid of it. Resveratrol is easy to miss among a long list of antiviral drugs, but it’s there [2].
So what is an antioxidant from red wine and berries doing on a list of “potentially therapeutic options for coronavirus”?
It’s still too early to say, and there’s no evidence that resveratrol can treat the new virus. Yet, scientists believe resveratrol is worth investigating in more detail. Earlier cell-based studies hint at its ability to fight MERS-CoV [3, 4].
To avoid confusion, the Middle East Respiratory Syndrome Coronavirus (MERS‐CoV) was first identified in 2012. What we are dealing with right now is a pandemic of a very similar, but distinct virus named SARS-CoV-2 or 2019-nCoV [5, 6].
Since the 2019 coronavirus is extremely recent, we are still lacking robust studies on it. No effective or FDA-approved products are yet available.
The best preventive measures you can take against 2019-nCoV are those of standard care: stay at home, wash your hands, and avoid touching your face.
Effects on Similar Viruses Like MERS & SARS
In one study, resveratrol prevented MERS-CoV infection in cells. It also helped infected cells live longer. This study earned resveratrol its place in the Nature commentary [3].
The MERS virus needs a kind of protein shell called nucleocapsid to survive and spread. In the mentioned study, resveratrol reduced nucleocapsid production. Most coronaviruses have nucleocapsid shells, likely including the 2019 coronavirus strain [7].
Resveratrol also reduced caspase 3, a sort of death signal cells send off. The less caspase 3, the less cells are dying from the virus [3].
In another cellular study, two synthetic compounds related to resveratrol blocked the replication of SARS-CoV. This is yet another coronavirus that emerged in 2003 and is similar to the strain behind the current outbreak [4].
Although promising, these studies are limited to cell-based experiments and other coronavirus strains. Until more research comes out, the effects of resveratrol on coronavirus remain unknown.
Clues from Mongolia
Mongolian scientists recently came forth with an unusual idea: Agsirga, a traditional Mongolian remedy, might hold some activity against the new coronavirus [8].
As it turns out, Agsirga contains resveratrol, along with almost 100 other active compounds. Using a computer simulation, scientists screened the compounds to see which ones can block pathways the new coronavirus uses to infect cells and multiply.
They revealed that a specific form of resveratrol (diglucoside) might stop coronavirus from binding to ACE2–the main passageway coronavirus uses to gain entry into cells.
Although many people hear about it for the first time, Mongolian medicine is an important part of traditional Chinese medicine. This study is just a starting point, and we can’t draw much from it. Mongolian scientists are hoping that Agsirga and its active compounds will be researched further as potentially useful amid the COVID-19 pandemic.
Broader Anti-Viral Potential
Other cell-based and animal studies additionally hint at resveratrol’s potential virus-fighting action. Resveratrol was active against:
- Influenza, which causes the common cold [9]
- Viruses that cause lung infections (the Respiratory Syncytial virus) in mice and in cells (Human meta pneumonia and Human rhinovirus virus); this effect was enhanced in with quercetin [9, 10]
- The virus that causes chickenpox (Varicella zoster) [10]
- African swine fever virus [10]
These viruses are different from the 2019 coronavirus strain.
Clinical studies are also lacking. Therefore, the effects of resveratrol on viral infections in humans remain unknown.
How Resveratrol Affects Antioxidant Status, Aging & Immunity
Researchers believe resveratrol may have dual antioxidant activity: it seems to directly fight free radicals and boost other antioxidant enzymes, genes, and pathways. Some also think it holds promise as an anti-aging compound [11, 12].
According to one theory, oxidative stress and inflammation trigger or worsen numerous chronic and aging-related diseases [13].
Data reveal that being over 60 years old and suffering from a chronic disease increases the chance of being admitted to the ICU and dying from COVID-19. A weak immune system is another big risk factor. Meanwhile, the coronavirus death rate for healthy people into their early 40s is estimated to be about 0.2% [14, 15].
Antioxidants contribute to strong immunity and general wellness, and they might be particularly important for the elderly. Getting enough dietary antioxidants along with a healthy lifestyle may help prevent many health problems down the line. Susceptibility to infection is one, but we have yet to see exactly how this plays out for the new coronavirus [16, 15].
Scientists have yet to explore the link between coronavirus, antioxidant status, aging pathways, and free radical damage.
With that in mind, let’s take a look at how resveratrol might enhance wellness. In previous cell-based and animal studies, resveratrol increased the following antioxidant enzymes:
- SOD and NRF2, crucial components of the detox hub and antioxidant defense [17]
- Glutathione, one of the body’s main antioxidants [17]
- Catalase, which protects from oxidative damage [17]
- Sirtuins and SIRT enzymes, which turn off aging-related genes and protect proteins [13]
At the same time, limited studies suggest that resveratrol reduces free radicals and inflammatory substances (including iNOS, Myeloperoxidase, NADPH oxidase). Severe inflammation has also been linked to worse COVID-19 outcomes [17, 18].
Resveratrol, Allergies & Lung Health
People with hay fever are more likely to suffer from lung diseases like COPD and respiratory infections [19].
In turn, having a lung disease increases the chance of dying from COVID-19. Over 6% of infected people with chronic lung or airway diseases die, compared to under 1% of healthy people of all ages, based on data from the Centers for Disease Control and Prevention (CDC) [20].
According to some clinical trials, resveratrol nose sprays may improve symptoms of hay fever or allergic rhinitis. Scientists came up with nose sprays as a way to bypass resveratrol’s poor bioavailability and get it straight to these problematic body areas.
In one study of 100 people, a nose spray containing resveratrol 0.1% reduced nasal symptoms and improved quality of life in adults with hay fever used three times daily for 4 weeks [21].
In another trial of 68 children with pollen-induced hay fever, a nose spray with resveratrol 0.05% and one other ingredient (beta-glucan 0.33%) improved itching, sneezing, runny nose, and nasal blockage. The same spray also helped prevent respiratory infections in another study of 73 children with hay fever [22, 23].
According to recent data, almost 70% of people with coronavirus disease (COVID-19) have a dry cough and a third have mucus. Resveratrol reduced inflammation and mucus in asthmatic mice, but its impact on COVID-19 is unknown [24, 25, 26, 27, 28, 29].
Pneumonia is a serious lung infection and another possible complication of severe COVID-19. In a clinical trial on 647 children with pneumonia, resveratrol enhanced the effectiveness of the antibiotic amoxicillin. This does not mean resveratrol should be added to COVID-19 protocols, though. Far more research is needed [30].
Potential Downsides to Resveratrol in COVID-19
Unanswered Questions
It’s still uncertain whether resveratrol increases or blocks ACE2 receptors, which coronavirus hijacks to enter cells.
According to limited data, resveratrol might lower blood pressure through the same mechanism as drugs called angiotensin receptor blockers. These drugs increase ACE2 receptors and have been linked to greater COVID-19 severity in some studies [31, 28, 32].
Lastly, resveratrol increased immune messengers called interferons in animals infected with viruses. Interferons probably help prevent coronavirus infection, but they might worsen inflammation in later stages. Too much interferon (type I IFN) causes lung complications in people with coronaviruses similar to the 2019 strain (SARS-CoV and MERS-CoV) [33, 34].
Both studies raise many questions that we’re unable to tackle at the moment. Future research should give us some answers.
Poor Bioavailability
Resveratrol has one well-known flaw: poor bioavailability. It is absorbed in the gut a bit better than other polyphenols (like quercetin) but gets broken down fast, leaving little free resveratrol in the bloodstream. Scientists say that this is one reason why a lot of the findings from animals and cells might not apply to humans [13].
Some ways to potentially increase the bioavailability of resveratrol include [35, 36]:
- Taking it with piperine, a natural compound found in black pepper
- Combining resveratrol with other polyphenols or flavonoids
- Searching for Liposomal or nano-resveratrol formulations
- Taking resveratrol along with a high-fat meal
Dosage & Precautions
Dosage
Most supplements will have 50-500 mg of resveratrol, although some contain up to 1,200 mg.
Clinical studies typically used 150-500 mg/day by mouth [37].
Evidence suggests that trans-resveratrol is the more active form (compared to cis-resveratrol). Make sure to check the supplement label.
Natural Sources
Resveratrol is found mostly in grape skin and red wine. “Itadori tea” (made from Japanese Knotweed) is another great source. Some berries, legumes, dark chocolate, peanuts also contain smaller amounts [38, 35].
Precautions & Side Effects
Clinical studies suggest that resveratrol is likely safe. High doses of bioavailable resveratrol may cause nausea and stomach upset. No long-term human studies have yet been carried out [13, 39, 40].
Resveratrol can interact with some drugs. It may also reduce iron absorption and/or blood levels, which could potentially worsen anemia [41, 42, 43].
Takeaway
Resveratrol is an antioxidant plant compound that is being researched for fighting coronavirus. Cell studies suggest it might be active against viruses similar to the strain behind the current pandemic.
Found in red wine and berries, resveratrol might also contribute to immune health and antioxidant defense. Getting more antioxidants from food, along with a healthy lifestyle, contributes to general wellness. This may help prevent chronic health problems and poor immunity, two big risk factors for getting a severe coronavirus infection and dying from it.
Yet, how antioxidant intake affects a person’s chance of getting coronavirus or suffering complications from it is still completely unknown.
Therefore, resveratrol supplementation is currently not recommended in COVID-19 due to a lack of reliable safety and efficacy data.
