Carnosic acid

PhytochemicalDiterpeneBest with a meal

What is it

Carnosic acid is a phenolic diterpene found primarily in rosemary (Rosmarinus officinalis) and sage (Salvia officinalis). It is a major antioxidant in these herbs and is used in food and supplements as a natural antioxidant preservative.

Evidence for 2 uses

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

Antioxidant / food preservation (utility)

Good Evidence

Carnosic acid is a well-established natural antioxidant used in food and supplements to prevent fat oxidation.

Neuroprotection (preclinical)

Mixed Evidence

Animal and cell studies show neuroprotective activity through Nrf2 activation, but no robust human clinical trials.

How it works

Carnosic acid is a powerful scavenger of free radicals and lipid peroxides. It is used by food manufacturers to protect fats and oils from rancidity, and in supplements both as a preservative and as a candidate active ingredient. Preclinical research has examined carnosic acid for neuroprotective effects, particularly in models of oxidative stress and neurodegeneration. It activates the Nrf2 pathway, upregulating endogenous antioxidant defenses. It has also shown anti-inflammatory and anti-cancer activity in laboratory studies, but human clinical evidence is limited.

Dosage

There is no recommended dose. Rosemary extracts are typically standardized to 5-25% carnosic acid; supplement servings provide 100-500 mg of extract. DSLD label data did not include a typical dose.

When and how to take it

WHEN: With meals. HOW: As rosemary extract capsules or as a food preservative.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Rosemary extract (standardized to carnosic acid)

Most common form.

Oral bioavailability is modest.

Carnosic acid as food antioxidant

Replaces synthetic preservatives like BHA/BHT in some foods.

Used at very small amounts.

Safety

Carnosic acid as part of rosemary extract has GRAS status. High doses of rosemary or extracts may cause GI upset, allergic reactions, and theoretical seizure risk in very high amounts.

Who should be cautious

Avoid medicinal-dose rosemary extracts in pregnancy (traditional use cautioned). Use caution if you have seizure disorders, take anticoagulants, or are on multiple prescription medications.

Interactions

Rosemary extracts may potentiate anticoagulant effects of warfarin and similar drugs. Carnosic acid may modulate cytochrome P450 enzymes affecting drug metabolism.

Food sources

Fresh rosemary

Amount
1 tbsp leaves - significant carnosic acid
%DV
—

Sage

Amount
1 tsp - significant amounts
%DV
—

Frequently asked questions

Is carnosic acid the same as carnosine?⌄

No - completely different compounds. Carnosic acid is a plant phenol. Carnosine is a peptide (beta-alanyl-L-histidine) found in muscle.

Should I take rosemary extract for antioxidant benefits?⌄

Rosemary extract may provide modest antioxidant activity. Robust human evidence for specific health outcomes is limited.

References

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

Research on Carnosic acid (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.