Evidence explainerQuercetin

Quercetin Phytosome vs Plain Quercetin: Absorption Differs up to 62-Fold

Most quercetin supplements are the plain aglycone, the form people absorb worst. A 2025 review of 31 human studies ranks the alternatives.

By Kymata Health editorial teamPublished October 9, 2026Last reviewed October 9, 2026

Medical review pending. Written by our editorial team from the studies cited below; a credentialed clinician has not reviewed it yet. Educational only, not medical advice.

Key takeaways

  • Across 31 human studies, quercetin-3-O-oligoglucosides were absorbed about 20 times better than quercetin aglycone [1].
  • Lecithin phytosome raised absorption 20.1-fold versus aglycone, and a fenugreek-galactomannan and lecithin formulation 62-fold [1].
  • Adding dietary fat and fibre roughly doubled quercetin absorption [1].
  • Most supplements contain the free aglycone, often at up to 1,000 mg a day [2].
  • The review measured absorption in blood and urine, not health outcomes [1].

Safety at a glance

From our Quercetin monograph. Published interactions and cautions only, each with its source.

Interactions

  • Certain prescription drugs. Short-term human and animal studies found quercetin altered the bioavailability of certain drugs.[8]

Who should be careful

  • Kidney problems. Animal studies suggest quercetin could enhance kidney-toxic effects in an already damaged kidney; a safety review lists this as a possible risk group.[8]
  • Hormone-sensitive conditions. Animal studies raised the possibility that quercetin could promote tumor development, especially in estrogen-dependent cancer; a safety review lists this as a possible risk group.[8]
  • High amounts long term. No adequate safety data exist for more than 12 weeks at 1,000 mg/day or more.[8]
  • Before you start. Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[8]

Full Quercetin safety section

The evidence, graded

Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.

  • Grade AWorsenedSystolic and diastolic blood pressureQuercetin · Meta-analysis · n=841 · 2022 · PMID 35948195Quercetin lowered systolic blood pressure by 2.38 mmHg overall and by 1.82 mmHg in people with normal blood pressure, and lowered diastolic pressure by 3.14 mmHg in people with elevated or high blood pressure.
  • Grade CImprovedEndurance performance and VO2maxQuercetin · Meta-analysis · n=288 · 2013 · PMID 22805526Endurance performance improved 0.74% and VO2max 1.94% versus placebo; the gain was significant only in untrained people, and the authors judged the effects likely trivial.

The forms on the shelf

Isolated quercetin is mostly sold as the free aglycone, frequently at daily doses of up to 1,000 mg [2]. Alternatives include glucoside forms such as isoquercetin and enhanced formulations such as phytosomes [1].

How they compare

A 2025 systematic review of 31 human intervention studies measured quercetin in blood or urine after different forms [1]:

  • Quercetin-3-O-oligoglucosides: about 2 times quercetin-3-O-glucoside, 10 times rutin and 20 times aglycone [1].
  • Glucoside-γ-cyclodextrin inclusion complex: 10.8-fold over aglycone [1].
  • Lecithin phytosome: 20.1-fold over aglycone [1].
  • Self-emulsifying fenugreek galactomannan with lecithin: 62-fold over aglycone [1].
  • Taking quercetin with dietary fat and fibre: about 2-fold [1].

What higher absorption does and does not tell you

These figures measure how much quercetin reaches blood or urine [1]. The blood-pressure and endurance trials pooled quercetin without separating forms, so it is not known whether a better-absorbed form changes those results [3][4]. See quercetin and blood pressure.

A safety review found no adequate data on more than 12 weeks at 1,000 mg/day or more [2]. The review's abstract does not address enhanced-absorption formulations [2].

Quick answers

What is quercetin dihydrate?

Our sources do not discuss the dihydrate label itself. Most supplements contain free quercetin aglycone [2], the form that ranked lowest for absorption [1].

Should quercetin be taken with food?

In the 2025 review, adding dietary fats and fibre roughly doubled absorption [1].

Is quercetin with bromelain absorbed better?

The 2025 absorption review's abstract does not list bromelain among the factors it assessed [1].

Keep reading

Full monographs

Related articles

Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.

References

  1. [1]Improving quercetin bioavailability: A systematic review and meta-analysis of human intervention studies. Food Chem, 2025. PMID 40037045
  2. [2]Safety Aspects of the Use of Quercetin as a Dietary Supplement. Mol Nutr Food Res, 2018. PMID 29127724
  3. [3]The Effects of Quercetin Supplementation on Blood Pressure - Meta-Analysis. Curr Probl Cardiol, 2022. PMID 35948195
  4. [4]Effects of quercetin supplementation on endurance performance and maximal oxygen consumption: a meta-analysis. Int J Sport Nutr Exerc Metab, 2013. PMID 22805526

Quercetin and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. This page has no product or affiliate links.

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