Quercetin for Brain Fog in Long Haul COVID
What Causes Brain Fog?
The exact causes of brain fog are not known. There are multiple reasons one might experience brain fog. One new possible reason under study is the issue of “zombie cells.” These are cells that are dormant and do not undergo routine programmed cell death. No cellular cleanup crew. When zombie cells linger, they result in a larger neuroinflammatory burden—leading to inflammatory cytokines and possibly resulting in brain fog symptoms: confusion, forgetfulness, a general lack of focus, and mental clarity
When looking at postmortem studies of those who died due to COVID-19, there is a 7-fold increase in these zombie cells. New drug trials are underway to determine if medications that target these zombie cells can help improve brain fog. One such medication under trial is dasatinib combined with quercetin. The former is an existing drug used to treat blood cancers. Quercetin is the main topic of this post.
What is Quercetin?
Quercetin, a flavonoid, resides at the forefront of phytochemicals, constituting an essential component of the plant kingdom. Flavonoids impart vibrant colors to fruits and vegetables, which protect plants from predators.
Quercetin has been well-studied for various effects, including:
Antioxidant Proficiency: Quercetin is a molecular shield against oxidative stress. By neutralizing free radicals, it contributes to cellular preservation and mitigates the cumulative effects of oxidative damage.
Anti-Inflammatory Properties: The anti-inflammatory capacities of quercetin are integral to maintaining homeostasis within the body. Its modulatory influence on inflammatory pathways positions it as a potential therapeutic agent in addressing inflammatory disorders.
Immunomodulatory Efficacy: Studies indicate that quercetin exhibits immunomodulatory effects, suggesting a role in fortifying the body's immune response. This attribute, coupled with anti-histamine properties, renders it a noteworthy consideration for individuals susceptible to allergies and asthma.
Heart Health: Some studies suggest that quercetin may have cardiovascular benefits. It may help lower blood pressure, reduce LDL cholesterol levels, and improve heart health.
Cognitive Function: The antioxidant properties of quercetin have led to investigations into its potential neuroprotective effects. Some studies suggest a role in protecting against age-related cognitive decline.
Viral Infections: Quercetin has been studied for its potential antiviral properties, including its ability to inhibit the replication of certain viruses. Some research has explored its use in supporting the immune system, particularly in the context of respiratory infections.
Food Sources of Quercetin
The best sources are onions, asparagus, capers, and red-leaf lettuce. Additional good sources come from broccoli, green peppers, and peas. Of the fruits, tomatoes, apples, cherries, and various berries have the highest quercetin content.
Bioavailability
Quercetin can cross the blood-brain barrier, potentially contributing to the removal of zombie cells. General supplementation suggests no more than 1g per day of quercetin. When choosing a supplement, be careful of quercetin metabolites and glycoside forms, as these are less neuroprotective and penetrate the blood-brain barrier less efficiently. Check the label for words like hesperidin-methyl-chalcone (HMC) or quercetin-chalcone. Liposomal or phytosomal forms are better options, but be careful with dosing as these forms will have higher potency. I like the product from Thorne, which can be found in the FullScript store: Thorne Quercetin Phytosome
Quercetin uptake can be enhanced with vitamin E. Taking quercetin at the same time you take a multivitamin can, therefore, potentially enhance uptake. This supplement should also be taken with foods to improve uptake.
Bottom Line
If you’re experiencing unrelenting brain fog, increase your intake of quercetin-rich foods and consider supplementing.
References
Costa LG, Garrick JM, Roquè PJ, Pellacani C. Mechanisms of Neuroprotection by Quercetin: Counteracting Oxidative Stress and More. Oxid Med Cell Longev. 2016;2016:2986796. doi:10.1155/2016/2986796 https://www.hindawi.com/journals/omcl/2016/2986796/
McClure, Paul. Drugs identified that may reverse brain fog caused by COVID-19. New Atlas. 2023 Nov 22. https://newatlas.com/medical/four-existing-drugs-may-reverse-premature-brain-aging-covid-19/
Ossola B, Kääriäinen TM, Männistö PT. The multiple faces of quercetin in neuroprotection. Expert Opin Drug Saf. 2009;8(4):397-409. doi:10.1517/14740330903026944 https://www.tandfonline.com/doi/full/10.1517/14740330903026944
