Flavonoids
Useful mainly for people with high dietary flavonoid intake from whole foods for cardiovascular benefit; limited benefit from isolated supplements.
Quick decision guide
May help most
People with high dietary flavonoid intake from whole foods for cardiovascular benefit; limited benefit from isolated supplements
Common dosing range
200–1,000 mg/day from citrus bioflavonoid extracts
When to expect effects
Weeks to months
Watch out for
High-dose supplements may inhibit drug-metabolizing enzymes (CYP3A4), altering levels of many medications
What is it
Flavonoids are a broad class of plant polyphenols with a 15-carbon skeleton, including flavones, flavonols, flavanones, flavan-3-ols, anthocyanins, and isoflavones. They are responsible for many fruit and flower pigments and bring antioxidant, vascular, and anti-inflammatory activity.
Is it worth it for you?
Use this as a quick fit check, not a diagnosis.
Worth considering if…
Probably skip if…
Evidence at a glance
| Goal | Effect | Best fit | Time |
|---|---|---|---|
cardiovascular health Limited Evidence | Modest reductions in blood pressure and endothelial function markers; strongest from dietary patterns | Adults with low dietary flavonoid intake or elevated cardiovascular risk | Weeks to months |
cardiovascular health
- Effect
- Modest reductions in blood pressure and endothelial function markers; strongest from dietary patterns
- Best fit
- Adults with low dietary flavonoid intake or elevated cardiovascular risk
- Time
- Weeks to months
Evidence for 1 use
AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.
cardiovascular health
Supplement benefitCohort data strongly associate high habitual flavonoid intake with lower cardiovascular disease risk. RCTs with flavonoid-rich foods (dark chocolate, tea, citrus) show modest reductions in blood pressure and improvement in endothelial function. Evidence for isolated flavonoid supplements is weaker than for whole dietary sources. The cardiovascular effects are likely mediated through improved endothelial nitric oxide availability and reduced platelet aggregation.
Bottom line: Dietary flavonoids support cardiovascular health; isolated supplement evidence is less compelling than whole-food intake.
Evidence is mixed
Strong observational evidence contrasts with inconsistent RCT results for isolated supplements; food-form flavonoids have stronger trial support than concentrated extracts.
How it works
How to take it
What to track
2 commercial forms
Compare the main delivery options and what they’re best suited for.
Citrus bioflavonoids
Common cheap source; quality varies.
Mostly metabolized by gut bacteria; circulating forms differ from those consumed.
Standardized extracts (quercetin, hesperidin, EGCG)
Allow defined doses of single flavonoids.
Variable; phytosome and liposomal forms improve absorption.
Safety
Know the common side effects, key cautions, and who should avoid it.
Common side effects
Serious risks
Drug interactions via CYP3A4 / P-glycoprotein inhibition at high doses
Who should avoid it
- People on narrow-therapeutic-index drugs without pharmacist clearance
Pregnancy & breastfeeding
Dietary flavonoid intake from food is safe in pregnancy; high-dose isolated flavonoid supplements have insufficient safety data and should be avoided.
Interactions
Flavonoids may inhibit CYP2C9, increasing warfarin levels and bleeding risk
CYP3A4 inhibition may increase statin exposure and myopathy risk
CYP3A4 inhibition (especially grapefruit flavonoids) increases drug levels
P-gp and CYP3A4 inhibition may raise cyclosporine levels
Food sources
| Food | Amount | %DV |
|---|---|---|
| Black or green tea (1 cup) | ~100-200 mg flavanols | — |
| Berries (1 cup) | ~100-300 mg anthocyanins+other | — |
| Citrus fruit (medium) | ~50-80 mg flavanones | — |
| Onion (1 medium) | ~50-100 mg quercetin | — |
Black or green tea (1 cup)
- Amount
- ~100-200 mg flavanols
- %DV
- —
Berries (1 cup)
- Amount
- ~100-300 mg anthocyanins+other
- %DV
- —
Citrus fruit (medium)
- Amount
- ~50-80 mg flavanones
- %DV
- —
Onion (1 medium)
- Amount
- ~50-100 mg quercetin
- %DV
- —
Choosing a product
What to look for on the label — and what to be skeptical of.
Look for…
Be skeptical of…
Frequently asked questions
Are flavonoids essential nutrients?⌄
No. They are bioactive phytochemicals, not essential, but associated with better health outcomes.
Should I take a flavonoid supplement?⌄
Most evidence supports flavonoid-rich foods over isolated supplements.
References by claim
Track Flavonoids with Pilora
Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.
Coming to App StoreDisclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.