Quercetin is a bioactive molecule classified as a flavonoid that plays many roles in support of human health. Quercetin is found in many fruits and vegetables, and it is particularly abundant in onions, apples, green tea, and wine. Quercetin has been studied in modern research for its potential to support the body’s response to oxidative stress and inflammation, cellular health, and cardiovascular function. Recent review articles have further elucidated the role of quercetin in the human body.

In a recent review, the role of quercetin is explored for its effects on cellular health, particularly in support of the endoplasmic reticulum (ER) in relation to stress. ER is an organelle responsible for many functions within the cell, including protein folding, lipid synthesis, and calcium storage. In the presence of stress, due to chronic inflammation or certain pathologies, changes to the ER can occur, including misfolded proteins and disruptions in calcium concentrations.

Research studies in both laboratory and clinical settings have explored the impact of quercetin on the ER in the presence of cellular stress. Quercetin has been shown to operate on a cellular level through several different pathways, including sirtuin1/adenosine monophosphate-activated protein kinase. It has been shown to decrease the production of reactive oxygen species and to help attenuate nitric oxide and inducible nitric oxide synthase production.

This review described many studies regarding quercetin and ER stress. One study explored the efficacy of quercetin on certain human leukemia cells. Quercetin was shown to reduce the expression of heat shock protein (Hsp)-70. The expression of Hsp70 is relatively low in healthy cells, but it’s higher in certain tumor types.

Quercetin may also support neuronal health. One animal study showed that quercetin modulated the expression of presenilin-1, a biochemical involved in the amyloid-beta plaque formation. Amyloid-beta plaques are associated with neurodegenerative diseases such as Alzheimer’s disease. Quercetin was also shown to influence the secretion of amyloid beta through the modulation of growth arrest and the DNA damage-inducible protein, GADD34, which plays a role in phosphorylation.

Cardiovascular and metabolic health may also be supported by quercetin. One study indicated that quercetin helped protect pancreatic beta cells from ER stress through its influence on nitric oxide signaling. An animal study involving diabetes showed a decrease in pancreatic ER stress-induced endothelial disorders in the presence of quercetin supplementation for 6 weeks.

This review illuminates the supportive role of quercetin for human health. However, there is a need for further research to fully understand its benefits. Quercetin may support cellular health and the body’s response to oxidative stress, neuronal health, and cardiovascular function.

By Colleen Ambrose, ND, MAT