Quercitin Dihydrate
Also known as: Quercetin, quercetin dihydrate, quercetin aglycone, Quercetin dihydrate
Overview
Quercetin dihydrate is a hydrated form of quercetin, a naturally occurring flavonoid polyphenol found abundantly in various fruits, vegetables, and grains like onions, apples, and berries. It is commonly used in dietary supplements due to its antioxidant, anti-inflammatory, antiviral, and cardioprotective properties. While it holds promise for conditions such as metabolic syndrome, cardiovascular disease, and viral infections (including COVID-19), its oral bioavailability is inherently low. This is primarily due to its poor water solubility, extensive first-pass metabolism in the liver, and rapid elimination from the body. Despite these challenges, ongoing research is exploring novel delivery systems, such as nanoemulsions and liposomes, to enhance its absorption and clinical efficacy. The research landscape for quercetin is moderately advanced, with numerous randomized controlled trials and meta-analyses supporting some of its clinical benefits, though the extent of these benefits can vary, and some outcomes remain inconclusive.
Benefits
Quercetin dihydrate offers several evidence-based benefits, primarily stemming from its anti-inflammatory and antioxidant properties. A meta-analysis of 16 randomized controlled trials demonstrated that quercetin supplementation significantly reduced total cholesterol, LDL cholesterol, and C-reactive protein (CRP), all key markers associated with cardiovascular risk. It also showed a modest reduction in systolic blood pressure by approximately 2.6 mmHg in overweight individuals with metabolic syndrome. For COVID-19 patients, a systematic review and meta-analysis of 5 RCTs indicated that quercetin supplementation significantly reduced lactate dehydrogenase (LDH) activity, hospital admission risk by 70%, ICU admission by 73%, and mortality by 82%. While these are significant relative risk reductions, they are based on a limited number of studies. Beyond these primary effects, preclinical and some clinical studies suggest antioxidant, antiviral, and potential anticancer activities, though the clinical evidence for these secondary effects is less robust. Benefits are most consistently observed in populations with metabolic syndrome, those at risk for cardiovascular disease, and COVID-19 patients. The time course for observing benefits typically ranges from 6 weeks to 3 months or more of consistent supplementation.
How it works
Quercetin dihydrate exerts its effects primarily by acting as a potent antioxidant, scavenging free radicals and modulating oxidative stress pathways within the body. It also possesses significant anti-inflammatory properties, achieved by inhibiting pro-inflammatory cytokines such as C-reactive protein (CRP) and various enzymes involved in the inflammatory cascade. Key molecular targets include the inhibition of the NF-κB pathway and the reduction of LDL oxidation. Furthermore, quercetin modulates lipid metabolism and improves endothelial function, contributing to its cardiovascular benefits. It primarily interacts with the cardiovascular, immune, and metabolic systems. Despite its beneficial mechanisms, quercetin faces challenges with poor oral bioavailability due to low water solubility, instability in the gastrointestinal tract, and extensive first-pass metabolism in the liver. Its half-life is approximately 25 hours, and its bioavailability can be improved by co-administration with fats or through advanced delivery systems.
Side effects
Quercetin dihydrate is generally considered safe when taken at recommended dosages. Studies, including a systematic review of 23 randomized controlled trials, have reported no significant adverse effects at doses up to 500 mg daily for durations of up to 3 months. Common side effects are rare and typically minor, with no consistent reports of gastrointestinal or systemic issues in controlled clinical trials. No dose-dependent adverse effects or acute toxicity have been identified. However, potential interactions with certain medications exist. Quercetin may interact with anticoagulants and some chemotherapeutic agents due to its modulation of cytochrome P450 enzymes, although the clinical significance of these interactions is not fully clear. Contraindications are not well-defined, but caution is advised for pregnant and breastfeeding individuals due to limited safety data in these populations. Safety in children has not been well established, but adult data support the use of moderate doses without significant risk.
Dosage
The minimum effective dose for quercetin dihydrate appears to be around 150 mg daily, which has shown effects on blood pressure and lipid markers. Optimal dosages typically range from 150 mg to 500 mg daily. A dose of 500 mg per day is considered safe and effective for short-term use, generally up to 3 months. There are limited long-term safety data beyond this period. For oral administration, it is recommended to take quercetin with meals, particularly fatty meals, as this can significantly enhance its absorption and bioavailability. The dihydrate form is stable, but ongoing research is exploring advanced formulations like nanoformulations or complexing agents to further improve its absorption. Co-administration with dietary fats or other bioavailability enhancers may lead to higher plasma levels and potentially greater efficacy.
FAQs
Is quercetin dihydrate safe?
Yes, quercetin dihydrate is generally considered safe at doses up to 500 mg/day for up to 3 months, with no significant adverse effects reported in clinical trials.
How long does it take to see benefits from quercetin?
Some benefits, such as effects on blood pressure and lipids, may be observed within 6 weeks. Benefits related to COVID-19 severity were seen during acute treatment phases.
Does quercetin interact with medications?
Possible interactions exist, particularly with anticoagulants and certain chemotherapeutic agents. It is advisable to consult a healthcare provider if you are taking other medications.
Is bioavailability a concern with quercetin?
Yes, oral bioavailability is low due to poor absorption and metabolism. Formulations designed to enhance absorption are recommended for better clinical efficacy.
Research Sources
- https://onlinelibrary.wiley.com/doi/10.1002/fsn3.3715 – This systematic review and meta-analysis of 5 RCTs involving 544 COVID-19 patients found that quercetin supplementation significantly reduced lactate dehydrogenase (LDH) activity, hospital admission risk by 70%, ICU admission by 73%, and mortality by 82%. The study highlights quercetin's potential in mitigating COVID-19 severity, despite some heterogeneity and a limited number of included studies.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10674654/ – This meta-analysis of 16 RCTs, including subjects with overweight or metabolic syndrome, demonstrated that quercetin supplementation significantly reduced total cholesterol, LDL cholesterol, and C-reactive protein (CRP). It also showed a modest reduction in systolic blood pressure by 2.6 mmHg, indicating cardiovascular benefits, although some inflammatory markers like IL-6 and TNF-α remained unchanged.
- https://vkm.no/download/18.111b9bb51900c58335fcde26/1718703086649/Rapport%20quercetin_rutin_final_130624-komprimert.pdf – This systematic review of 23 RCTs assessed the safety of quercetin in adults across various health statuses. The findings indicate that quercetin is safe at doses up to 500 mg/day for durations up to 10 months, with no significant adverse effects reported. The study provides strong evidence for the short-to-medium term safety of quercetin in adult populations.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC11594109/ – This systematic review focuses on the pharmacokinetics of quercetin, highlighting that its poor oral bioavailability significantly limits its clinical utility. The review discusses various advanced delivery systems and co-administration strategies that are being investigated to improve quercetin's absorption and plasma levels, primarily drawing from preclinical data.
