Quercetin: Effects on Hormones, PCOS, and Inflammation

Quercetin is a widely studied flavonoid relevant to hormonal health. Studies show it has antiandrogenic, anti-inflammatory, and insulin-sensitizing properties. The data is promising but still heterogeneous. This article explains what the research truly shows.

Key takeaways

Quercetin is a polyphenol that shows anti-androgenic, anti-inflammatory, and insulin-sensitizing properties in studies.
Clinical studies in PCOS patients show changes in testosterone, LH, and insulin resistance, but the data is still heterogeneous.
In clinical studies, 500 mg to 1 g per day was used. These are study amounts, not dosage recommendations.
The bioavailability of quercetin is low (under 10%). Combination with vitamin C, folate, or high-fat meals improves absorption.
There are no approved health claims for quercetin yet. Further research is needed.

Quercetin is one of the most thoroughly studied flavonoids relevant to hormonal health. Clinical studies have described its effects on androgen levels, insulin sensitivity, and inflammatory markers in PCOS patients. The evidence is promising, but still heterogeneous. Not a miracle cure, but a well-researched plant compound.

What is Quercetin?

Quercetin is a bioactive flavonoid from the polyphenol group, one of the most common plant pigments. It is being investigated in studies on metabolic and hormonal processes, inflammatory pathways, and gut microbiome interactions. Clinical evidence: available, but heterogeneous.

Quercetin is found in high concentrations in many plant foods. Regular consumption can naturally support quercetin status.

Capers

~234 mg/100g

Dried Dill

~55 mg/100g

Red Onions

~39 mg/100g

Kale

~23 mg/100g

Oregano

~42 mg/100g

Apples with skin

~4 mg/100g

What do clinical studies show for PCOS?

Between 50 and 70 percent of women with PCOS exhibit insulin resistance. Quercetin is increasingly being researched in this context because it could act through several mechanisms simultaneously.

Hormone Status

Androgens and LH

Vaez et al. (2023) observed changes in testosterone and LH levels with quercetin in PCOS patients. Habiburrahman et al. (2023) also reported changes in hormonal markers. Whether this leads to clinically relevant effects is still under investigation.

Vaez et al. 2023; Habiburrahman et al. 2023

Insulin Sensitivity

AMPK and Glucose Uptake

Dhanya et al. (2022) describe that quercetin could activate AMPK signaling pathways and influence glucose uptake in experimental models. Rezvan Neda et al. (2018) observed effects on adiponectin receptors and AMPK in PCOS patients.

Dhanya et al. 2022; Rezvan Neda et al. 2018

Inflammation

Cytokines and NF-κB

Several studies describe an influence on pro-inflammatory cytokines like TNF-α and IL-6, which are often elevated in PCOS. Quercetin inhibits NF-κB signaling pathways in experimental models.

Amiri et al. 2022; Gorczyca et al. 2022; Islam et al. 2022

Gut Microbiome

Bacterial Composition

Changes in gut microbiota often occur in PCOS. Experimental models investigated whether quercetin influences bacterial composition and the production of short-chain fatty acids. Promising, but no clinical confirmation yet.

Cani PD et al.

Classification of Evidence

The current results are promising, but the data is still heterogeneous. There are no approved health claims for quercetin yet. General therapeutic recommendations cannot be derived from existing studies. Further high-quality RCTs are needed.

Bioavailability: The Most Important Problem

The bioavailability of quercetin is low—less than 10 percent without appropriate measures. This is the most important practical factor when taking it.

Measure	Effect	Evidence
Combine with Vitamin C	Measurably improves plasma levels	Shafabakhsh et al. 2019
Combine with Folate	Increased absorption	Shafabakhsh et al. 2019
Take with fat	Better absorption (olive oil, avocado)	Andres et al. 2018
Regular intake	Improves bioavailability over time	Andres et al. 2018
Other Flavonoids	Synergistic effect possible	Shafabakhsh et al. 2019

Clinical studies used 500 mg to 1 g of quercetin per day. These figures reflect study amounts and are not intake recommendations. Whether and in what form supplementation is advisable should always be discussed with a doctor.

Did you know?

Quercetin is naturally found in very high amounts in red onions, kale, dill, and capers. A single tablespoon of dried dill contains more quercetin than many low-dose supplement capsules. This is not an argument against supplements, but an argument for understanding diet as the foundation.

Estrogen Regulation and Other Areas of Action

Studies on quercetin and estrogen balance have been contradictory so far. Some studies show effects on follicular development and estrogen markers, while others report opposite findings. The effect is likely dependent on the woman's initial hormonal status, necessitating a differentiated approach.

Quality of life and mood: A randomized study in patients with type 2 diabetes (Mantadaki et al., 2024) reported improvements in quality of life parameters such as sleep and anxiety under quercetin supplementation. Whether these results can be extrapolated to PCOS is currently unclear, but many women try it individually.

Quercetin and apigenin compared: Both are flavonoids from the group of polyphenols, but they act through partly different mechanisms. Quercetin belongs to the flavonols and shows particularly strong anti-inflammatory and insulin-sensitizing properties. Apigenin belongs to the flavones and acts more strongly via androgenic receptors and calming GABA receptor mechanisms. In combination, they complement each other and are therefore both included in Cycle+.

Cycle+: Quercetin and Apigenin combined

Cycle+ Formula contains quercetin along with apigenin, myo-inositol, and other cycle-relevant active ingredients. Developed by doctors, manufactured in Austria.

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Dosage and Practical Application

In clinical studies, dosages between 500 mg and 1 g of quercetin per day were used. A dosage of 1 g daily was used in studies with PCOS patients and showed improvements in metabolic function and hormonal markers (Rezvan Neda et al., 2018). Another study with type 2 diabetes patients used 500 mg daily (Mantadaki et al., 2024).

These figures exclusively reflect the quantities used in studies. They do not constitute a recommendation for intake. Whether and in what form supplementation is advisable should always be discussed with a doctor.

Time of intake: Most studies do not provide clear statements about the best time for intake. Since bioavailability is improved with fat and vitamin C, it is recommended to take it with a main meal.

Safety: Quercetin is considered well-tolerated at the amounts used in studies. In very high doses, gastrointestinal discomfort may occur. During pregnancy, lactation, and when taking medication, medical consultation is necessary before supplementation.

What Quercetin cannot do

Quercetin is not a PCOS medication and does not replace medically supervised treatment. There are no approved health claims for quercetin in the EU. General therapy recommendations cannot be derived from the existing studies because:

Most positive studies are small and short, often under six months. Many results come from experimental models, not from human RCTs. The data on estrogen regulation is contradictory. Long-term safety data is largely lacking.

This does not mean that quercetin is ineffective, but that research is not yet complete. It is a well-researched plant compound with biologically plausible mechanisms that can be useful as part of a comprehensive strategy, but it is not a substitute for lifestyle adjustments, insulin management, or medical treatment.

Questions about quercetin and your hormone profile?

Our medical team will review your lab results and let you know if and how quercetin fits into your individual plan.

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Summary of Key Points

Quercetin is a polyphenol with antiandrogenic, anti-inflammatory, and insulin-sensitizing properties in studies.
Clinical data in PCOS show effects on testosterone, LH, insulin resistance, and inflammatory markers. However, the data is still heterogeneous.
Bioavailability is low (under 10%). Combination with vitamin C, folate, or fatty meals improves absorption.
Study dosages ranged from 500 mg to 1 g daily. These are not dosage recommendations.
There are no approved health claims yet. Quercetin does not replace medical treatment.
Best natural sources: capers, dill, red onions, kale, oregano, apples with skin.

Frequently Asked Questions about Quercetin

What does quercetin do for PCOS?

Clinical studies have described effects on androgen markers such as testosterone and LH, on insulin resistance, and on inflammatory parameters. In experimental models, quercetin activates insulin signaling pathways like AMPK, inhibits inflammatory cytokines, and influences adiponectin receptors. The results are promising, but the data is still heterogeneous. General therapeutic statements cannot yet be derived from it.

How much quercetin should one take?

In clinical studies, 500 mg to 1 g per day were used. These figures reflect study quantities and are not a recommendation for intake. Whether and in what form supplementation makes sense should always be discussed with a doctor. Bioavailability is low and is improved by combination with vitamin C, folate, or fatty meals.

Which foods are high in quercetin?

The richest sources are capers, dill, red onions, kale, oregano, apples with skin, cranberries, cherries, spinach, and asparagus. Regular consumption of these foods can naturally support quercetin levels.

Does quercetin have side effects?

In clinical studies with 500 mg to 1 g daily, quercetin was described as well-tolerated. At very high doses, gastrointestinal discomfort may occur. During pregnancy and breastfeeding, and when taking medication, a doctor should be consulted before supplementation.

Is quercetin the same as apigenin?

No, both are flavonoids from the polyphenol group, but with different chemical structures and action profiles. Quercetin belongs to the flavonol subgroup, apigenin to the flavones. Both exhibit anti-inflammatory and hormone-related properties, but act through partly different mechanisms. Hormonic Cycle+ contains both active ingredients.

Scientific Sources

Habiburrahman M et al. (2023). Quercetin effects on hormonal and metabolic markers in PCOS.
Dhanya R et al. (2022). Quercetin and AMPK activation in experimental models of insulin resistance.
Rezvan Neda et al. (2018). Quercetin effects on adiponectin receptors and AMPK activity in PCOS patients.
Vaez S et al. (2023). Quercetin and androgen markers in PCOS.
Mantadaki AE et al. (2024). Quercetin supplementation and quality of life in type 2 diabetes.
Amiri P et al. (2022). Quercetin and inflammatory cytokines.
Gorczyca G et al. (2022). Quercetin in inflammatory signaling pathways.
Islam T et al. (2022). Quercetin and cytokine profiles.
Cani PD et al. Gut microbiota changes in PCOS.
Shafabakhsh R et al. (2019). Bioavailability of quercetin and enhancement strategies.
Andres S et al. (2018). Quercetin bioavailability and safety.

About the Author

Lisa Maria Emmer

Physician & Chief Medical Officer · Hormonic

Lisa Maria Emmer is co-founder and medical director at Hormonic. She supports women with hormonal problems every day and specializes in cycle health, PCOS, and menopause.

This article is for informational purposes only and does not replace medical advice, diagnosis, or treatment. If you have existing medical conditions, are pregnant or breastfeeding, or are taking medication, you should consult a doctor before taking any dietary supplements.

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Quercetin in PCOS: Effect on Hormones, Insulin, and Inflammation