iridoids

PhytochemicalIridoidBest with a meal

What is it

Iridoids are a large family of plant compounds (monoterpenoids with a cyclopentane ring fused to a six-membered oxygen ring) found in many medicinal plants. Familiar examples include aucubin (plantain, eyebright), harpagoside (devil's claw), and oleuropein (olive leaf). Iridoid glycosides are the glucose-conjugated forms.

Evidence for 2 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Joint pain (specific iridoid-rich extracts)

Good Evidence

Devil's claw (harpagoside) and certain other iridoid-rich extracts show modest pain reductions in osteoarthritis and low back pain trials.

General antioxidant or anti-aging effects (iridoids as a class)

Mixed Evidence

There is no body of clinical evidence supporting 'iridoids' as a class for any specific outcome; benefits are tied to particular compounds and extracts.

How it works

Iridoids and their glycosides interact with diverse biological targets. After oral intake, glycosides are largely hydrolyzed by gut bacteria to release the more lipophilic aglycones, which are absorbed and reach circulation. Reported activities include anti-inflammatory effects (through NF-kB modulation and prostaglandin inhibition), antioxidant activity, hepatoprotection, and modulation of neurotransmitter systems. Clinical evidence for specific iridoid-rich extracts (devil's claw for joint pain, noni juice for general wellness, olive leaf for blood pressure) is variable. Evidence for iridoids 'as a class' is not a useful frame; effects depend on which specific iridoid, what other compounds are in the extract, and the indication.

Dosage

There is no RDA for iridoids. Doses in supplement extracts are typically expressed as content of a marker iridoid (such as harpagoside in devil's claw, or oleuropein in olive leaf). Follow product labeling for the specific extract.

When and how to take it

Most iridoid-containing extracts are taken once or twice daily with food. Specific timing depends on the source product.

1 commercial form

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Standardized herbal extract (specific iridoid marker)

How iridoids are typically encountered in supplements.

Glycosides are hydrolyzed in the gut; aglycones are absorbed.

Safety

Most iridoid-containing herbal extracts are well tolerated at typical doses. Reported side effects are usually mild GI upset, headache, or skin reactions. Some iridoids can be bitter and irritating to mucous membranes at high concentrations. Long-term safety of isolated iridoids is generally not well characterized.

Who should be cautious

Pregnancy and breastfeeding cautions depend on the source extract. People with bleeding disorders, on antihypertensives, or with chronic GI conditions should review the specific iridoid-rich product they are considering with a clinician.

Interactions

Interactions depend on the specific iridoid-containing extract. Devil's claw can affect anticoagulants; olive leaf can lower blood pressure. No class-wide interaction summary is meaningful.

Food sources

Olives and olive leaf (oleuropein)

Amount
highly variable
%DV
—

Plantain herb (aucubin)

Amount
trace in food
%DV
—

Frequently asked questions

Are iridoids antioxidants?⌄

Many iridoids show antioxidant activity in laboratory assays. Clinical relevance in humans depends on the specific compound and dose.

Should I look for 'iridoids' on a supplement label?⌄

It is more useful to look for the specific marker compound that matches the intended use (for example, harpagoside in devil's claw for joint pain).

References

iridoids on Wikidata — Wikidata link

iridoids on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on iridoids (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: 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.