Shiso (Perilla frutescens): Benefits, Uses, Dosage, and Safety in Herbal Medicine

What is Shiso (Perilla Frutescens)?

Shiso, also known as Perilla frutescens, is a flowering plant native to East Asia, commonly used in traditional herbal medicine for its aromatic leaves and seeds, which are valued for their medicinal properties and culinary applications.

Botanical Classification and Taxonomy

The scientific name of Shiso is Perilla frutescens. This plant belongs to the kingdom Plantae, division Magnoliophyta, class Lamiales, order Lamiales, family Lamiaceae, genus Perilla, and species Perilla frutescens. It is known as shiso in Japan, perilla in China, and shiso or perilla in Korea. The synonyms for this plant include Perilla frutescens var. frutescens, Perilla japonica, and Perilla cordata.

The following table shows the full taxonomy of this plant.

Plant Description and Morphology

Shiso is an upright annual herb that typically grows to a height of 30 to 60 centimeters with a branched stem that is slightly hairy.

Its leaves are ovate to lanceolate, with serrated edges and a glossy, dark green upper surface. The small, inconspicuous flowers are arranged in terminal clusters and are pale purple or white in color. The root system is fibrous and shallow, allowing the plant to anchor itself and absorb nutrients efficiently.

The leaves have a slightly peppery aroma, a crisp texture, and a vibrant green color that intensifies when dried.

Native Habitat and Distribution

Shiso is native to East Asia, particularly China, Japan, and Korea, where it has been traditionally used in herbal medicine and cuisine.

Its geographic distribution extends across temperate regions of Asia, including parts of Southeast Asia and the Himalayas. The plant thrives in mild climates with cool summers and moderate rainfall, typically in regions with temperate to subtropical conditions. It prefers well-drained soil and partial to full sunlight, growing best in areas with consistent moisture.

Shiso is often found in moist, open areas such as riverbanks, fields, and forest edges, where it can spread easily through its rhizomatous root system.

Plant Parts Used Medicinally

The leaves and seeds of Shiso are the primary plant parts used medicinally.

The leaves are typically harvested when young and tender, while the seeds are collected when fully mature. Both parts contain bioactive compounds that contribute to its medicinal properties. The leaves are often used fresh or dried in herbal preparations.

The seeds are ground and used in various traditional formulations.

Phytochemical Composition

Shiso contains a variety of active compounds that contribute to its medicinal properties, including volatile oils, flavonoids, and polyphenols.

Secondary metabolites such as rosmarinic acid, caffeic acid, and flavonoids like quercetin and kaempferol are prominent in its composition. These compounds exhibit antioxidant, anti-inflammatory, and antimicrobial activities. Chemical markers like perillartine and methyl perillate are unique to shiso and are responsible for its characteristic aroma and some therapeutic effects.

The combination of these phytochemicals underpins its use in traditional herbal medicine.

Pharmacological Properties

Shiso exhibits a range of pharmacological properties that make it valuable in herbal medicine.

Its therapeutic actions include anti-inflammatory, antioxidant, and antispasmodic effects. Biologically, it contains compounds such as rosmarinic acid and perillartins that contribute to its activity. Pharmacodynamically, these compounds interact with cellular pathways to modulate immune responses and reduce oxidative stress.

System-level effects include relief of respiratory conditions and support for gastrointestinal health.

Mechanisms of Action

Shiso exerts its therapeutic effects through multiple mechanisms involving cellular processes, biochemical pathways, and interactions with specific target systems.

At the cellular level, it modulates ion channels and receptors, influencing membrane potential and neuronal activity. Biochemically, shiso contains compounds like rosmarinic acid and perillarin that act as antioxidants and anti-inflammatory agents, interfering with pro-inflammatory signaling cascades. These compounds also interact with key enzymes such as cyclooxygenase and lipoxygenase, reducing oxidative stress and inflammatory responses.

Target systems include the central nervous system, gastrointestinal tract, and immune system, where shiso demonstrates neuroprotective, digestive, and immunomodulatory properties.

Therapeutic Uses

Shiso is used in herbal medicine to treat a variety of conditions due to its anti-inflammatory, antispasmodic, and carminative properties.

It is commonly employed to alleviate digestive issues such as bloating, indigestion, and gastrointestinal discomfort. The plant is also used to reduce symptoms of respiratory conditions like coughing and bronchitis. Additionally, shiso has been utilized to support liver health and detoxification processes in the body.

Its high content of antioxidants and essential oils contributes to its effectiveness in treating inflammatory and allergic conditions.

Preparation Methods and Forms

The preparation methods of Shiso for use in herbal medicine involve various forms, including fresh leaves, dried leaves, and essential oils.

Fresh Shiso leaves are commonly used in teas and culinary applications, though they are also incorporated into medicinal formulations. Dried Shiso leaves are often ground into powder or steeped in hot water to make infusions. Essential oils extracted from the leaves are used in aromatherapy and topical applications.

The plant may also be prepared as a tincture or decoction depending on the desired therapeutic effect.

Dosage and Administration

The typical dosage of Shiso for medicinal use ranges from 3 to 10 grams of fresh leaves or 1 to 3 grams of dried leaves per day, depending on the specific condition being treated and the guidance of a qualified practitioner.

Safety, Side Effects, and Contraindications

When used in recommended doses, Shiso is generally safe, but it may cause mild gastrointestinal discomfort, allergic reactions, or interactions with certain medications, particularly those affecting the central nervous system or blood clotting.

Drug Interactions

Shiso may interact with certain medications due to its high content of flavonoids and essential oils, which can affect liver enzyme activity and potentially alter the metabolism of drugs such as anticoagulants, antiplatelets, and antidepressants.

Toxicity and Precautions

Shiso is generally considered safe when used in typical culinary amounts, but it may cause mild gastrointestinal upset in some individuals, and excessive use could lead to adverse effects, particularly in those with existing health conditions or taking certain medications.

Cultivation and Harvesting

Shiso is typically cultivated in temperate climates with well-drained soil and partial shade, requiring regular watering and fertilization, and is harvested during the summer months when the leaves are most aromatic and flavorful.

Processing and Extraction

The processing and extraction of Shiso involve methods such as drying, crushing, and solvent-based extraction to obtain its active compounds, including essential oils, flavonoids, and alkaloids, which are used in herbal formulations.

Storage and Shelf Life

Shiso leaves and seeds should be stored in a cool, dry place in a sealed container, with fresh leaves kept refrigerated in a plastic bag to maintain their potency and flavor for up to two weeks.

Scientific Research and Evidence

Scientific research on Shiso (Perilla frutescens) has demonstrated its potential anti-inflammatory, antioxidant, and antimicrobial properties, with studies suggesting its use in managing conditions such as hypertension, diabetes, and gastrointestinal disorders.

Traditional and Historical Uses

Shiso has been traditionally used in East Asian medicine for centuries to aid digestion, reduce inflammation, and promote respiratory health, with historical references dating back to ancient Chinese and Japanese herbal texts.

Regulatory Status

In many countries, Shiso is considered a food ingredient rather than a medicinal herb, and its regulatory status varies by region, with some jurisdictions requiring specific labeling or restrictions on its use in herbal products.

Sustainability and Conservation

In many countries, Shiso is considered a food ingredient rather than a medicinal herb, and its regulatory status varies by region, with some jurisdictions requiring specific labeling or restrictions on its use in herbal products.