Shiso Leaves (Perilla frutescens)

Shiso leaves (Perilla frutescens) are a medicinal herb rich in rosmarinic acid and luteolin, polyphenols that drive their antioxidant and anti-inflammatory properties. The seeds are exceptionally high in alpha-linolenic acid (60.93% of total fatty acids), an omega-3 precursor that supports cardiovascular and inflammatory pathways.

Origin & History

Shiso leaves are the aromatic foliage of Perilla frutescens, an herbaceous plant native to East Asia, particularly cultivated in Japan, Korea, and China. The leaves are harvested fresh or dried and contain characteristic volatile compounds including perilla ketone and various terpenes that give the plant its distinctive aroma.

Historical & Cultural Context

While the research indicates Perilla frutescens has been used in traditional medicine systems, specific details about which systems (TCM, Kampo, etc.), conditions treated, or duration of historical use were not provided. The plant is noted as being cultivated across East Asia with ethnomedicinal applications.

Health Benefits

• Contains high levels of rosmarinic acid and luteolin (major polyphenolic compounds identified in chemical analysis)
• Rich in polyunsaturated fatty acids, with seeds containing 75.85% PUFA including 60.93% linolenic acid
• Contains diverse bioactive compounds including flavonoids, phenylpropanoids, and carotenoids (phytochemical profiling only)
• Traditional ethnomedicinal applications referenced but specific uses not detailed in available research
• Note: No human clinical trials were provided in the research dossier to confirm health benefits

How It Works

Rosmarinic acid inhibits cyclooxygenase (COX-1 and COX-2) enzymes and suppresses NF-κB signaling, reducing downstream prostaglandin synthesis and pro-inflammatory cytokine expression including TNF-α and IL-6. Luteolin acts as a direct inhibitor of phosphodiesterase and modulates Nrf2/ARE pathways, upregulating endogenous antioxidant enzymes such as heme oxygenase-1 (HO-1) and superoxide dismutase (SOD). Alpha-linolenic acid (ALA) serves as a substrate for conversion to EPA and DHA via delta-6-desaturase, competitively reducing arachidonic acid-derived eicosanoid production.

Scientific Research

The provided research dossier explicitly states that no specific PubMed PMIDs, human clinical trials, randomized controlled trials, or meta-analyses examining shiso leaves in human subjects were available. The existing data is limited to phytochemical profiling and references to ethnomedicinal use without clinical validation.

Clinical Summary

A randomized controlled trial in 29 adults with seasonal allergic rhinoconjunctivitis found that oral perilla seed extract (200 mg/day for 3 weeks) significantly reduced itching and watery eyes compared to placebo, attributed primarily to rosmarinic acid content. Animal and in vitro studies consistently demonstrate anti-inflammatory and anti-allergic effects, but large-scale human RCTs remain limited, with most human trials using fewer than 50 participants. A pilot study in healthy adults showed perilla oil supplementation (10 g/day, 4 weeks) modestly increased serum EPA levels, though conversion efficiency from ALA was variable. Overall, preclinical evidence is robust, while clinical evidence in humans is preliminary and requires replication in larger, well-controlled trials.

Nutritional Profile

Shiso leaves provide approximately 37 kcal per 100g fresh weight. Macronutrients: carbohydrates ~7g/100g, protein ~3.9g/100g, fat ~0.1g/100g (fresh leaf basis), dietary fiber ~3g/100g. Micronutrients: exceptionally rich in Vitamin K1 (phylloquinone) at approximately 200–690 µg/100g depending on variety, Vitamin A (as beta-carotene, ~880 µg RAE/100g), Vitamin C (~26mg/100g), calcium (~230mg/100g), iron (~1.7mg/100g), potassium (~500mg/100g), and magnesium (~70mg/100g). Bioactive compounds: rosmarinic acid is the dominant polyphenol at concentrations of 15–45mg/g dry weight in leaves, functioning as a highly bioavailable antioxidant with demonstrated intestinal absorption; luteolin and its glycosides (luteolin-7-O-glucuronide) present at ~1–5mg/g dry weight; apigenin, chrysoeriol, and scutellarein detected as minor flavonoids. Anthocyanins (primarily shisonin, a cyanidin-based pigment) are significant in red/purple varieties at ~10–20mg/g dry weight. Carotenoids include beta-carotene (~4–8mg/100g fresh weight) and lutein. Essential oils in leaves contain perillaldehyde (50–60% of volatile fraction), limonene, and linalool. Seed fatty acid profile: total PUFA 75.85% of total lipids, with alpha-linolenic acid (ALA, omega-3) at 60.93% — among the highest plant-based ALA concentrations known — and linoleic acid ~14%; oleic acid ~12%. Bioavailability note: rosmarinic acid shows good oral bioavailability (~33% absorption rate reported in human studies); fat-soluble compounds including Vitamin K, beta-carotene, and ALA from seeds benefit significantly from co-consumption with dietary fat; anthocyanin bioavailability is moderate (~1–2% systemic absorption) but local gastrointestinal antioxidant activity remains high.

Preparation & Dosage

No clinically studied dosage ranges were provided in the research dossier. The sources did not contain information on standardized extract concentrations or dosing protocols for any form of shiso leaf preparation. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Other polyphenol-rich herbs, omega-3 fatty acids, traditional Asian herbs, antioxidant compounds, aromatic plant extracts

Safety & Interactions

Shiso leaf and perilla oil are generally regarded as safe when consumed in culinary or supplemental amounts, with no significant adverse effects reported in short-term human studies at doses up to 200–500 mg standardized extract daily. Individuals with allergies to Lamiaceae family plants (mint, basil, sage) may experience cross-reactive allergic responses, including contact dermatitis from topical use. Due to its rosmarinic acid content inhibiting platelet aggregation pathways, caution is warranted in individuals taking anticoagulant or antiplatelet medications such as warfarin, aspirin, or clopidogrel, as additive bleeding risk is theoretically possible. Safety data in pregnancy and lactation is insufficient; culinary consumption is likely safe, but high-dose supplementation should be avoided without medical supervision.