Spearmint

Metadata

Approved Indications

Commission E (Germany)

• No Commission E monograph for spearmint (Mentha spicata) as a medicinal herb
• Note: Commission E has a positive monograph for peppermint (Mentha x piperita) — these are distinct species with different phytochemistry and indications

ESCOP

• No ESCOP monograph for spearmint
• ESCOP monographs exist for peppermint leaf and peppermint oil — not applicable to spearmint

EMA/HMPC

• No EMA/HMPC monograph for spearmint (Mentha spicata)
• EMA has well-established and traditional use monographs for peppermint — these do not extend to spearmint
• Spearmint lacks the high menthol content that defines peppermint’s pharmacological profile

Important Distinction from Peppermint

Spearmint and peppermint are frequently confused but are pharmacologically distinct:

Spearmint’s therapeutic identity in modern research is defined by its anti-androgenic effects and high polyphenol content, neither of which is shared with peppermint.

Conditions Treated

Primary (Clinical Evidence from RCTs)

• Hyperandrogenism in PCOS: Reduction of free testosterone, normalization of LH/FSH ratio, increase in estradiol
• Hirsutism (idiopathic and PCOS-related): Hormonal improvement demonstrated; clinical hair reduction requires longer treatment duration than studied
• Androgenic symptoms in women: Acne, oily skin, and hormonal hair growth linked to elevated androgens (extrapolated from hormonal data)

Secondary (Supported by Clinical Trials)

• Cognitive function / working memory: Improvement in age-associated memory impairment with high-polyphenol spearmint extract (900 mg/day for 90 days)
• Attention and reaction time: Enhanced complex attention in healthy active adults with spearmint extract supplementation

Traditional / Supportive

• Digestive support: Carminative, antispasmodic — traditional use for flatulence, nausea, and dyspepsia across multiple cultures
• Respiratory complaints: Traditional use for cough, congestion, and cold symptoms
• Antioxidant support: High ORAC value and rosmarinic acid content provide significant free radical scavenging

Mechanism of Action

Anti-Androgenic Mechanism (Primary)

The anti-androgenic effect of spearmint operates through multiple, complementary pathways:

1. Reduction of free testosterone: Consistently demonstrated in human trials; spearmint tea significantly decreases circulating free testosterone in women with PCOS and hirsutism
2. Steroidogenic enzyme modulation: Animal studies (Kumar et al., 2008) demonstrated decreased expression of key steroidogenic enzymes:
   • Cytochrome P450scc (cholesterol side-chain cleavage)
   • Cytochrome P450C17 (17-alpha-hydroxylase)
   • 3-beta-hydroxysteroid dehydrogenase (3-beta-HSD)
   • 17-beta-hydroxysteroid dehydrogenase (17-beta-HSD)
   • Steroidogenic acute regulatory protein (StAR)
   • Androgen receptor expression
3. Gonadotropin modulation: Increases LH and FSH levels, suggesting a central (hypothalamic-pituitary) component to the mechanism
4. Hepatic androgen clearance: Proposed enhancement of hepatic processing and elimination of androgens

The net effect is a reduction in bioavailable androgens without suppressing total testosterone to the same degree, suggesting the mechanism is distinct from pharmaceutical anti-androgens like spironolactone or finasteride.

Key Bioactive Compounds

Cognitive Enhancement Mechanism

The cognitive benefits of spearmint extract are attributed primarily to its high polyphenol content, particularly rosmarinic acid:

• Antioxidant neuroprotection: Rosmarinic acid scavenges reactive oxygen species in neural tissue
• Anti-inflammatory effects: Reduction of neuroinflammation via inhibition of COX and LOX pathways
• Cholinergic modulation: Rosmarinic acid has demonstrated acetylcholinesterase inhibitory activity in vitro
• BDNF upregulation: Polyphenols may support brain-derived neurotrophic factor expression

Clinical Evidence Summary

Anti-Androgenic Effects: Key Clinical Trials

Akdogan et al. 2007 — Pilot Study in Hirsutism

“Effect of spearmint (Mentha spicata Labiatae) teas on androgen levels in women with hirsutism”

Results:

• Free testosterone: Significantly decreased (p < 0.05)
• LH: Significantly increased (p < 0.05)
• FSH: Significantly increased (p < 0.05)
• Estradiol: Significantly increased (p < 0.05)
• Total testosterone: No significant change
• DHEAS: No significant change

Limitations: No placebo control; very short duration (5 days); hirsutism was not clinically scored at endpoint. This was a proof-of-concept study demonstrating hormonal changes only.

Significance: First human study to demonstrate spearmint’s anti-androgenic hormonal effects, providing the rationale for the subsequent RCT.

Grant 2010 — Randomized Controlled Trial in PCOS

“Spearmint herbal tea has significant anti-androgen effects in polycystic ovarian syndrome. A randomized controlled trial”

Results:

• Free testosterone: Significantly decreased in spearmint group vs. placebo (p < 0.05)
• Total testosterone: Significantly decreased in spearmint group vs. placebo (p < 0.05)
• LH: Significantly increased (p < 0.05)
• FSH: Significantly increased (p < 0.05)
• Subjective hirsutism (modified DQLI): Significantly improved in spearmint group (p < 0.05)
• Objective hirsutism (Ferriman-Gallwey score): No significant difference between groups (p = 0.12)

Key interpretation: The hormonal changes were robust and consistent with the pilot study, but the lack of objective hirsutism improvement is expected given the biology of hair growth — androgen-dependent follicular changes require many months to manifest visually. Grant noted that the 30-day study duration was insufficient to assess clinical hair reduction and proposed longer future studies.

Strengths: Randomized design; placebo control; two-center recruitment; hormonal endpoints well-measured.

Limitations: Small sample size (n = 42); short duration (30 days); no blinding details reported; single publication from one research group.

Preclinical Support: Animal Studies

Cognitive Enhancement: Clinical Trials

Herrlinger et al. 2018 — Working Memory in Age-Associated Memory Impairment

“Spearmint extract improves working memory in men and women with age-associated memory impairment”

Results:

• Quality of working memory: 15% improvement with 900 mg/day vs. placebo (p = 0.0469)
• Spatial working memory accuracy: 9% improvement with 900 mg/day vs. placebo (p = 0.0456)
• 600 mg/day: No significant improvement vs. placebo
• Sleep quality: Improved in 900 mg/day group (secondary endpoint)
• Dose-response: Significant dose-response effect between 900 mg and 600 mg groups

Note: Study funded by Kemin Industries, the manufacturer of the Neumentix spearmint extract.

Falcone et al. 2019 — Attention in Healthy Active Adults

“The attention-enhancing effects of spearmint extract supplementation in healthy men and women”

Results:

• Complex attention: Significant improvement at day 7 vs. placebo
• Shifting attention test: Significant improvement
• Sustained attention (4-part continuous performance test): Significant improvement
• Agility: Improved reactive agility performance

Note: Also funded by Kemin Industries. Extends the cognitive findings from older adults to a younger, active population.

Evidence Summary Table

Safety Profile

Overall Safety Assessment

Spearmint is generally recognized as safe (GRAS) by the US FDA as a food flavoring and is consumed worldwide as a common beverage tea. The safety profile is exceptionally favorable compared to pharmaceutical anti-androgens.

Contraindications

• Known hypersensitivity to spearmint or other Lamiaceae family members (basil, rosemary, sage, thyme, lavender)
• Iron deficiency anemia (theoretical): Tannin and polyphenol content may reduce non-heme iron absorption when consumed with meals
• Severe kidney disease: Large amounts may theoretically exacerbate renal conditions (based on limited preclinical data; clinical relevance uncertain)
• Severe liver disease: Same precautionary reasoning as kidney disease

Drug Interactions

• No clinically significant drug interactions have been documented for spearmint tea at standard doses
• Sedative medications (theoretical): Spearmint may have mild sedative properties; additive effects with CNS depressants are theoretically possible but not clinically reported
• Iron supplements: Polyphenol/tannin content may reduce iron absorption if taken simultaneously; separate by 2 hours
• Anti-androgenic drugs (spironolactone, finasteride, flutamide): Theoretical additive anti-androgenic effect; clinical significance unknown but worth monitoring

Side Effects

• At typical tea doses (2 cups/day): Essentially no side effects reported in clinical trials
• Possible: Mild heartburn or gastroesophageal reflux (relaxation of lower esophageal sphincter, as with other mints)
• Rare: Allergic contact dermatitis (topical); oral allergic reactions in mint-sensitive individuals
• Overconsumption: Nausea, vomiting, stomach irritation reported only with excessive amounts

Pregnancy and Lactation

• Pregnancy Category C: Insufficient human data. Large doses of spearmint are traditionally cautioned against in pregnancy due to possible uterotonic effects. Moderate consumption as a culinary herb or occasional tea is generally considered acceptable, but therapeutic doses (2+ cups daily for anti-androgenic effect) should be avoided during pregnancy. The anti-androgenic mechanism is of particular theoretical concern during fetal development.
• Lactation: Insufficient data. No adverse effects reported at culinary doses. Therapeutic anti-androgenic doses have not been studied during lactation.

Comparison with Pharmaceutical Anti-Androgens

Clinical Dosage

Spearmint Tea (Most Studied Form)

Spearmint Extract (Cognitive Indications)

Forms and Preparations

Clinical Pearls

• Hair growth cycle: Even with effective androgen reduction, visible improvement in hirsutism requires 6—12 months due to the anagen-telogen hair cycle; patients should be counseled on realistic timelines
• Consistency matters: Daily consumption is important; the anti-androgenic effect likely depends on sustained exposure
• Quality: Use pure Mentha spicata leaf; do not substitute peppermint (Mentha x piperita), which has a different phytochemical profile and lacks the same anti-androgenic evidence
• Combination approaches: Spearmint tea can be used alongside other evidence-based PCOS interventions (inositol, metformin, lifestyle modifications) — no contraindications to combination use have been reported

Sources

• Grant P. Spearmint herbal tea has significant anti-androgen effects in polycystic ovarian syndrome. A randomized controlled trial. Phytother Res. 2010;24(2):186-188. PMID: 19585478
• Akdogan M, Tamer MN, Cure E, et al. Effect of spearmint (Mentha spicata Labiatae) teas on androgen levels in women with hirsutism. Phytother Res. 2007;21(5):444-447. PMID: 17310494
• Akdogan M, Ozguner M, Kocak A, Oncu M, Cicek E. Effects of peppermint teas on plasma testosterone, follicle-stimulating hormone, and luteinizing hormone levels and testicular tissue in rats. Urology. 2004;64(2):394-398. PMID: 15302514
• Kumar V, Kural MR, Pereira BM, Roy P. Spearmint induced hypothalamic oxidative stress and testicular anti-androgenicity in male rats. Food Chem Toxicol. 2008;46(12):3563-3570. PMID: 18804513
• Sadeghi Ataabadi M, Alaee S, Bagheri MJ, Bahmanpoor S. Role of essential oil of Mentha spicata (spearmint) in addressing reverse hormonal and folliculogenesis disturbances in a polycystic ovarian syndrome in a rat model. Adv Pharm Bull. 2017;7(4):651-654. PMID: 29399556
• Herrlinger KA, Nieman KM, Sanoshy KD, et al. Spearmint extract improves working memory in men and women with age-associated memory impairment. J Altern Complement Med. 2018;24(1):37-47. PMID: 29314866
• Falcone PH, Nieman KM, Tribby AC, et al. The attention-enhancing effects of spearmint extract supplementation in healthy men and women. Nutr Res. 2019;64:24-38. PMID: 30802720
• Mahendran G, Rahman LU. Ethnomedicinal, phytochemical and pharmacological updates on peppermint (Mentha x piperita L.) — a review. Phytother Res. 2020;34(9):2088-2139. PMC: 9019422
• Nouri H, Azin M, Khoshvaghti A. The traditional uses, phytochemistry and pharmacology of spearmint (Mentha spicata L.): A review. J Ethnopharmacol. 2021;278:114266. PMID: 34087400
• Bardaweel SK, Bakchoul MM, AlSalamat HA, et al. Association of herbal tea and follicle-stimulating hormone, anthropometric parameters, and fasting blood glucose levels among PCOS women: a systematic review and meta-analysis. Clin Nutr Res. 2024;13(3):201-214
• Moreno L, Bello R, Beltran B, et al. A descriptive overview of the medical uses given to Mentha aromatic herbs throughout history. Foods. 2020;9(12):1839. PMC: 7767097

Connections

• Compare with Peppermint — closely related species but pharmacologically distinct; peppermint is menthol-dominant and used for IBS/digestive complaints, while spearmint is carvone-dominant and used for anti-androgenic effects; they should not be used interchangeably for therapeutic purposes
• Compare with Vitex / Chasteberry — both used in women’s hormonal health but through different mechanisms; Vitex acts via dopamine D2 receptor agonism to reduce prolactin, while spearmint directly reduces free testosterone; they address different aspects of the PCOS hormonal picture and could theoretically be complementary
• Compare with Red Clover — both are women’s health herbs with hormonal activity; Red Clover contains phytoestrogens (isoflavones) for menopausal symptoms, while spearmint is anti-androgenic; different patient populations and indications
• Compare with Saw Palmetto — both have anti-androgenic mechanisms involving 5-alpha-reductase and steroidogenic enzyme modulation; saw palmetto is used for BPH in men, while spearmint is used for hyperandrogenism in women; the mechanistic parallel is notable despite the different clinical contexts