You’ve probably heard of flavonoids before, since they’ve been mentioned so often in health circles. If you’re unfamiliar with them, flavonoids are powerful antioxidants that have anti-inflammatory properties. Quercetin is a flavonol-type antioxidant (a class of flavonoids) that exists naturally in many foods.

It’s present in apples, tea, red wine, onions, mustard, grapes, and berries, and has shown to have many immune system benefits. It also has a positive effect on glucose homeostasis, which is how insulin and glucagon balance to maintain blood glucose.

Quercetin has been proposed to impact (and reduce) the inflammatory cascade—the series of inflammation-related issues within the body found in conditions like PCOS. 

Since inflammation is the root of so many health issues and diseases, reducing it is of major benefit on countless levels.

Quercetin in Blueberries

Quercetin Study on Women with PCOS

78 women with PCOS took part in a 12-week study.(1) In it, they were either given 1,000 mg of Quercetin daily, or a placebo.

Researchers looked at the participants’ testosterone levels, as well as their LH, glucose, weight, and body measurements.

They also measured resistin levels—an important hormone made by the immune cells that surround fat cells (adipocytes).

As we know, PCOS is associated with fat cell dysfunction. Immune cells have to clean up a lot of the damage in these tissues, and when they do, they secrete resistin.

As such, resistin is a marker of this type of fat cell dysfunction, which is found so often in PCOS.

Resistin levels also increase in people with insulin resistance and type 2 diabetes.

The study found that the women taking quercetin had lower levels of LH and testosterone, as well as significant resistin reductions.

Related post: Excess Carbohydrates in PCOS, and Their Link with Inflammation

Quercetin levels in foods

Other studies done in the past have found similar benefits to quercetin. Diabetic rats that were given quercetin showed a marked reduction in a number of different diabetes-related markers. This included decreases in TNF‐α, blood pressure, body mass index (BMI), hyperinsulinemia, insulin resistance, and dyslipidemia.(2) 

Rats with PCOS that had quercetin administered to them also showed significantly reduced insulin, androgens, and lipid profile levels. (3)

It appears that quercetin creates these positive effects, at least in part, by reducing resistin’s expression and plasma concentration.

The 12-week study was conducted to investigate whether quercetin supplementation in overweight or obese women with PCOS would have similar beneficial effects. 

As with the rats, special focus was placed on the women’s metabolic and hormonal parameters. The benefits on the plasma concentration and gene expression of resistin were marked. This indicates that this supplement likely provides excellent metabolic and anti-inflammatory benefits in PCOS.

A quality quercetin supplement can be found here, and the chart above shows several common, easily found foods that are rich in quercetin as well.


1. The effects of quercetin supplementation on metabolic and
hormonal parameters as well as plasma concentration and gene
expression of resistin in overweight or obese women with
polycystic ovary syndrome. Khorshidi, Moini, Alipoor, Rezvan, Gorgani-Firuzjaee, Yaseri, Hosseinzadeh-Attar, 2018

2. Rivera, Morón, Sánchez, Zarzuelo, & Galisteo, 2008

3. Shah & Patel, 2016