Cellular senescence is a process in which some cells, after becoming stressed or damaged, may undergo irreversible changes including resistance to apoptosis and increased metabolic activity. It is a potential driver of many processes leading to age-related diseases (ARD). Studies suggest that even a relatively small quantity of senescent cells (SCs) may cause tissue dysfunction. Tissues containing SCs may be more vulnerable to disease onset and progression, increased inflammation, and decreases in function with time. Sirtuin 1 (SIRT1) is believed to be a regulator of cellular senescence. Certain phytochemicals, such as quercetin, may influence the SIRT1 response and the body’s potential to clear SCs. 

Quercetin is a molecule that is abundant in onions, apples, green tea, and other fruits and vegetables. Classified as a flavonoid, studies have shown that quercetin supports the body’s response to oxidative stress, neuroinflammation, and the elimination of SCs. A recently published review article by Cui and colleagues explored the many biochemical pathways that quercetin may impact SIRT1 activity and SCs.  

The authors describe recent studies that attribute quercetin’s ability to help reduce reactive oxygen species (ROS) by increasing the activity of SIRT1. The SIRT1 activation may help modulate the expression of amyloid-β and tau, two molecules associated with neurodegenerative diseases, such as Alzheimer’s disease (AD). An animal study involving AD mouse models reported improvements in markers related to cognitive function and neurodegeneration after quercetin administration. Another study involving quercetin administration showed improvements in signaling pathways related to AD progression including SIRT1/FoxO.  

In animal studies related to Parkinson’s disease (PD), quercetin administration helped reduce oxidative damage, restore mitochondrial homeostasis, and increase neuronal density. It also helped regulate SIRT1 pathways involving nuclear factor-κB (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2). Quercetin administration has also been shown to help modulate inflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor in studies related to Huntington’s disease. In animal studies related to depression, quercetin was shown to help support healthy serotonin levels and help reduce oxidative stress and neuroinflammation.  

Studies indicate that quercetin may also support many of the other systems in the body, including musculoskeletal health. It has been shown to help mediate several biochemical pathways associated with osteoporosis by influencing SIRT1, inflammatory responses, and osteoblast apoptosis. It may also support the cardiovascular system; studies indicate it may help protect against myocardial apoptosis and help protect against certain age-related cardiovascular changes.  

The aging process is a complex system of cellular changes. Phytochemicals, such as quercetin, may support healthy aging, the body’s response to oxidative stress, and a healthy inflammatory response.  

By Colleen Ambrose, ND, MAT