Rosmarinic acid
Summary
Rosmarinic acid is a polyphenol in lemon balm, perilla and spearmint. In a 96-week trial of 323 older adults, lemon balm extract with 500 mg/day did not slow cognitive decline overall. Small trials reported fewer seasonal-allergy symptoms with an enriched perilla extract (29 people, 21 days) and better working memory with high-rosmarinic spearmint extract (90 people).
Key facts
- A caffeic-acid ester found in lemon balm (Melissa officinalis), perilla, spearmint and other mint-family herbs[1][4][5]
- 323 older adults with subjective or mild cognitive impairment: 500 mg/day for 96 weeks did not change cognitive scores versus placebo[2]
- After lemon balm extract with 500 mg rosmarinic acid, blood levels peaked at about 1 hour; food increased exposure and delayed the peak[3]
- 29 people with mild seasonal allergies: an enriched perilla extract raised responder rates for itchy nose and eyes and watery eyes over 21 days[4]
- No serious adverse events and no changes in liver, kidney or blood tests in the lemon balm trials[1][3]
- 4 graded human outcomes on this page
- October 13, 2026
How it works
ProposedIn lab and animal studies rosmarinic acid blocks amyloid-beta fibril formation and has antioxidant and anti-inflammatory effects. In the perilla allergy trial it lowered neutrophils and eosinophils in nasal fluid. Whether these effects matter at the blood levels reached in people is not established.[2][4][3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Cognition | Grade C | No effect | RCT · n = 323 · 2023 | 3 rows |
| Allergy | Grade D | Improved | RCT · n = 29 · 2004 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Cognitive decline in older adults without dementia | No effect | Grade C | RCT · n = 323 · 2023 Older adults with subjective or mild cognitive impairment (Japan) Form: Lemon balm (Melissa officinalis) extract · Dose: 500 mg/day rosmarinic acid · Duration: 96 weeks plus 24-week washout No differences in ADAS-cog or other cognitive measures versus placebo at 96 weeks. An exploratory analysis limited to participants without hypertension found a statistically significant difference in CDR Sum of Boxes (p = 0.036), which the authors read as a possible benefit. | 36502333 (opens PubMed)Source [2] |
| Working memory and sleep onset in age-associated memory impairment | Improved | Grade D | RCT · n = 90 · 2018 Adults with age-associated memory impairment, mean age 59 (USA) Form: Spearmint extract high in rosmarinic acid · Dose: 600 or 900 mg/day of extract · Duration: 90 days At 900 mg/day, quality of working memory improved 15% and spatial working memory accuracy 9% versus placebo, and people reported falling asleep more easily; 600 mg/day was not reported as significant for these outcomes. | 29314866 (opens PubMed)Source [5] |
| Seasonal allergic rhinoconjunctivitis symptoms | Improved | Grade D | RCT · n = 29 · 2004 Adults with mild seasonal allergic rhinoconjunctivitis (Japan) Form: Perilla frutescens extract enriched for rosmarinic acid · Dose: 50 or 200 mg/day of enriched extract · Duration: 21 days Responder rates for itchy nose, watery eyes, itchy eyes and total symptoms rose versus placebo; nasal neutrophils and eosinophils fell. No adverse events. | 14988517 (opens PubMed)Source [4] |
| Safety, cognition and behaviour in mild Alzheimer's dementia | Mixed | Grade D | RCT · n = 23 · 2020 Patients with mild dementia due to probable Alzheimer's disease (Japan) Form: Lemon balm extract · Dose: 500 mg/day rosmarinic acid · Duration: 24 weeks Safe and well tolerated (primary endpoint). Cognitive scores did not differ; the neuropsychiatric NPI-Q score improved 0.5 points versus a 0.7-point worsening on placebo (P = 0.012). | 33122694 (opens PubMed)Source [1] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Lemon balm extract standardised to rosmarinic acid | Varies[3] | Total rosmarinic acid peaked at about 1 hour (162 nmol/L after 500 mg, fasted); food raised exposure and delayed the peak.[3] | No changes in liver, kidney or blood tests after single doses; no serious adverse events over 24 and 96 weeks.[3][1][2] | Alzheimer's and mild cognitive impairment trials (500 mg/day rosmarinic acid) |
| Perilla extract enriched for rosmarinic acid | Varies[4] | No human absorption data in the cited trial.[4] | No adverse events and normal blood tests over 21 days.[4] | Seasonal allergy trial (50–200 mg/day) |
| High-rosmarinic acid spearmint extract | Varies[5] | No absorption data in the cited trial.[5] | No safety concerns reported in the abstract over 90 days.[5] | Memory trial (600–900 mg/day) |
Studied doses
Doses studied in human trials ranged from 50–200 mg/day of an enriched perilla extract (21 days) to 500 mg/day of rosmarinic acid in lemon balm extract (24–96 weeks) and 600–900 mg/day of high-rosmarinic acid spearmint extract (90 days).[4][1][2][5]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Sedatives and sleep medicines (lemon balm extracts)RCTA single 600 mg dose of standardised lemon balm extract raised calmness and lowered self-rated alertness, so lemon-balm-based rosmarinic acid products could add to sedation. No studies of isolated rosmarinic acid with these drugs exist.[6]
Who should be careful
- Pregnancy, breastfeeding and children
- Trials enrolled adults only, so there are no safety data for these groups.[1][2][4]
- Before driving (lemon balm products)
- A 600 mg dose of lemon balm extract reduced self-rated alertness in a lab study.[6]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
- Check the source herbProducts standardise lemon balm, perilla, spearmint or rosemary extracts to rosmarinic acid; trials tested specific extracts, not pure rosmarinic acid.[1][4][5]
- Rosmarinic acid vs extract weightThe lemon balm trials dosed 500 mg of rosmarinic acid itself; the spearmint trial dosed 900 mg of whole extract.[2][5]
Cost per studied dose, without the sales pitch
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Cost per studied dose
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Frequently asked questions
What is rosmarinic acid?
A polyphenol found in lemon balm, perilla, spearmint, rosemary and other mint-family herbs.[1][4][5]
Does rosmarinic acid improve memory?
The largest trial, 323 older adults over 96 weeks, found no overall benefit. A smaller spearmint-extract trial reported better working memory at 900 mg/day.[2][5]
Does it help with hay fever?
One 21-day trial in 29 people found more symptom responders with an enriched perilla extract than placebo.[4]
Is rosmarinic acid safe?
Lemon balm extract with 500 mg/day was well tolerated for up to 96 weeks with no serious adverse events.[1][2][3]
Should it be taken with food?
Food increased how much rosmarinic acid was absorbed and delayed its peak.[3]
Sources
- [1]Safety and efficacy of Melissa officinalis extract containing rosmarinic acid in the prevention of Alzheimer's disease progression.. Sci Rep, 2020. RCT
- [2]Effects of Melissa officinalis Extract Containing Rosmarinic Acid on Cognition in Older Adults Without Dementia: A Randomized Controlled Trial.. J Alzheimers Dis, 2023. RCT
- [3]Pharmacokinetics, Safety and Tolerability of Melissa officinalis Extract which Contained Rosmarinic Acid in Healthy Individuals: A Randomized Controlled Trial.. PLoS One, 2015. PK-study
- [4]Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, inhibits seasonal allergic rhinoconjunctivitis in humans.. Exp Biol Med (Maywood), 2004. RCT
- [5]Spearmint Extract Improves Working Memory in Men and Women with Age-Associated Memory Impairment.. J Altern Complement Med, 2018. RCT
- [6]Attenuation of laboratory-induced stress in humans after acute administration of Melissa officinalis (Lemon Balm).. Psychosom Med, 2004. crossover-RCT
What changed
- Independent adversarial review: MCI trial subgroup reworded neutrally: the abstract's reported direction of the CDR-SB change is ambiguous, so the page no longer asserts "less worsening".
- Second-pass self-review: every PMID re-checked against NCBI esummary (title, year, no retraction or expression-of-concern flag), every dose, n and duration re-read against the PubMed abstract or PMC full text, grades held conservative, and interactions limited to what a cited source supports.
- First draft. Source titles and years taken from NCBI E-utilities esummary; abstracts read for every evidence row.