Querceitin
Also known as: Quercetin, Quercetol, 3,3',4',5,7-Pentahydroxyflavone
Overview
Quercetin is a flavonoid widely found in fruits, vegetables, and grains, particularly in apples, onions, tea, and parsley. This plant pigment exhibits powerful antioxidant and anti-inflammatory effects. It is commonly utilized as a dietary supplement aimed at improving cardiovascular health, regulating blood pressure, supporting the immune system, and managing metabolic syndrome. Research suggests that quercetin may play a role in reducing blood pressure and improving lipid profiles, with moderate evidence stemming from randomized controlled trials (RCTs) and systematic reviews highlighting its health benefits. Despite the variable quality of studies, there is a growing consensus on its efficacy in certain health domains, establishing a scientific foundation for its use as a supplement.
Benefits
Quercetin has several evidence-supported benefits: (1) **Blood Pressure Reduction**: It has been shown to significantly lower systolic and diastolic blood pressure, with meta-analyses indicating reductions around -3.04 mmHg and -2.63 mmHg respectively. (2) **Lipid Profile Improvement**: Quercetin supplementation is associated with decreases in total cholesterol and LDL levels. (3) **COVID-19 Outcomes**: It has been linked with favorable outcomes in COVID-19 patients, including reduced risks of hospitalization and mortality. (4) **Inflammation Reduction**: Quercetin may decrease levels of C-reactive protein (CRP), reflecting its anti-inflammatory properties. These benefits are most noted in populations dealing with metabolic syndrome and other cardiovascular risks, with substantial effect sizes observed in numerous studies.
How it works
Quercetin exerts its effects mainly through its antioxidant and anti-inflammatory properties. It neutralizes free radicals, thereby reducing oxidative stress. Furthermore, quercetin inhibits pro-inflammatory cytokines and enzymes, modulating inflammatory responses. This flavonoid improves cardiovascular health by enhancing endothelial function and promoting vasodilation, contributing to lower blood pressure levels.
Side effects
Quercetin is generally regarded as safe, with minimal adverse effects reported. The most common side effects (>5%) include gastrointestinal disturbances such as nausea and diarrhea. Less frequently (1-5%), users may experience allergic reactions or mild interactions with medications. Rare side effects (<1%) can occur, including severe allergic reactions. Notably, quercetin may interact with anticoagulants and certain other drugs. It is advised that individuals who are pregnant, breastfeeding, or have kidney or liver disease seek medical advice before supplementation to ensure safety and avoid potential contraindications.
Dosage
For effective blood pressure reduction, quercetin doses of at least 500 mg/day are recommended. Typical dosages range from 500 mg to 1000 mg per day, with the maximum safe limit generally considered to be 1000 mg/day. While no specific timing for intake has been established, consistent daily consumption is advised to achieve optimal results. It's important to note that the bioavailability of quercetin can vary based on its form (aglycone vs. glycoside) and absorption may be enhanced with the presence of dietary fats. There are no specific cofactors required for effective absorption, although vitamin C may potentially increase its bioavailability.
FAQs
Is Quercetin Safe for Everyone?
Quercetin is generally safe for most individuals, but those with specific health conditions should consult a healthcare provider.
How Long Does It Take to See Benefits?
Benefits from quercetin supplementation may typically be noticed within several weeks of consistent use.
Can Quercetin Interact with Medications?
Yes, quercetin has potential interactions; it's advisable to consult a healthcare professional if on medication.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/27405810/ – This meta-analysis involving 587 patients indicates that quercetin supplementation can lead to significant reductions in both systolic and diastolic blood pressure, particularly at doses of 500 mg/day or higher.
- https://pubmed.ncbi.nlm.nih.gov/38258783/ – This systematic review and meta-analysis reports that quercetin supplementation is associated with decreased risks of hospital and ICU admission as well as reduced mortality rates in COVID-19 patients.
- https://onlinelibrary.wiley.com/doi/abs/10.1002/fsn3.3715 – This meta-analysis of 896 participants notes that while quercetin effectively lowers blood pressure, it does not significantly impact lipid profiles or glucose levels.
- https://pubmed.ncbi.nlm.nih.gov/31017459/ – The findings suggest quercetin's impact on lipid profiles and overall metabolic health but call for comprehensive studies to fully understand its biological mechanisms.
- https://academic.oup.com/nutritionreviews/article-abstract/78/8/615/5697189?redirectedFrom=fulltext&login=false – This review covers the diverse health effects of flavonoids, including quercetin, underlining its role in managing conditions like hypertension, but the conclusions emphasize a cautious approach due to the need for further research.
