Puha

Sonchus oleraceus

Common & Folk Names

• Puha (Māori)
• Pūhā
• Rauriki
• Common Sowthistle
• Smooth Sowthistle
• Annual Sowthistle
• Sow Thistle
• Milk Thistle (not to be confused with Silybum marianum)
• Hare’s Thistle
• Hare’s Lettuce

Plant Family

Asteraceae (Daisy Family)

Geographic Location

Native to Europe, North Africa, and Western Asia. Now cosmopolitan, found on every continent except Antarctica. Introduced to Aotearoa New Zealand over 1,000 years ago, where it has become naturalised and is widespread throughout both the North and South Islands.

Habitat

Puha thrives in disturbed ground, cultivated areas, gardens, roadsides, waste places, and pastures. It prefers nutrient-rich, well-drained soil in full sun to partial shade. In New Zealand, it grows from coastal areas to montane zones, often appearing spontaneously in cultivated ground.

Growing Conditions

Sun: Full sun to partial shade

Soil: Fertile, well-drained soil with neutral to slightly alkaline pH (6.5-7.5); tolerates a wide range of soil conditions

Propagation: Easily grown from seed; self-seeds readily. Seeds germinate in spring when soil temperatures reach 10-15°C

Care: Minimal care required as it is vigorous and somewhat weedy. Regular harvesting encourages tender new growth. Can be cultivated as a cut-and-come-again salad green.

NZ Planting Calendar

Sowing (seeds): Spring to autumn (September–May) – germinates readily

Planting: Year-round in mild areas; spring (September–November) in cooler regions

Growth: Annual or short-lived perennial; self-seeds prolifically

Flowering: Year-round; peaks in summer (December–February)

Harvest (leaves): Year-round; best in cooler months (April–September) for less bitterness

Note: Not native to NZ; naturalized weed throughout the country; edible introduced species; S. kirkii (raurīroa) is a native NZ species

Harvesting Guidelines

Harvest young leaves and tender growing tips before flowering for the best flavour and texture, as leaves become increasingly bitter with age. The optimal time is in spring and early summer when growth is most vigorous. Harvest in the morning after dew has dried for best quality. Flowers can also be harvested when in bud or just opening. Roots are best dug in autumn when energy is stored below ground.

Parts Used

• Leaves (fresh or dried)
• Young stems and shoots
• Flower buds and flowers
• Roots
• Milky sap (latex)

Constituents & their Actions

Puha is rich in bioactive compounds that contribute to its nutritional and medicinal properties. The main constituents include phenolic acids, flavonoids, sesquiterpene lactones, vitamins, and minerals.

Phenolic Acids:

These compounds have potent antioxidant and anti-inflammatory properties, which in turn protect cells from oxidative damage and reduce inflammatory processes throughout the body. Some of the main phenolic acids in puha are:

• Chicoric acid (caftaric acid derivative)
• Chlorogenic acid
• Caftaric acid
• Caffeic acid

The main actions of these phenolic acids are:

• Antioxidant
• Anti-inflammatory
• Antimicrobial
• Blood sugar modulation

Flavonoids:

These polyphenolic compounds are powerful antioxidants that neutralise free radicals, which in turn prevents cellular damage and supports healthy ageing. Some of the main flavonoids in puha are:

• Luteolin
• Apigenin
• Quercetin
• Kaempferol
• Luteolin-7-O-glucoside
• Isoquercitrin
• Astragalin

The main actions of these flavonoids are:

• Antioxidant
• Anti-inflammatory
• Antiproliferative
• Neuroprotective

Sesquiterpene Lactones:

These compounds, characteristic of the Asteraceae family, have bitter properties and contribute to digestive stimulation and anti-inflammatory effects. Some of the sesquiterpene lactones in puha are:

• Eudesmanolides
• Guaianolides
• Lactucin derivatives

The main actions of these sesquiterpene lactones are:

• Digestive bitter
• Anti-inflammatory
• Mild sedative
• Antimicrobial

Vitamins & Minerals:

Puha is exceptionally nutrient-dense, containing significant amounts of vitamins and minerals that support overall health. Key nutrients include:

• Vitamin C (ascorbic acid) – high levels
• Vitamin A (from carotenoids)
• B-vitamins (B1, B2, niacin)
• Calcium
• Phosphorus
• Iron

The main actions of these nutrients are:

• Antioxidant (especially vitamin C)
• Immune support
• Nutritive tonic
• Blood building

Actions with Mechanisms

Antioxidant:
The high concentration of phenolic acids, particularly chicoric acid and chlorogenic acid, along with flavonoids like luteolin and quercetin, neutralise free radicals by donating electrons, which in turn stabilises reactive oxygen species and prevents oxidative damage to cellular structures. These compounds also upregulate the body’s endogenous antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase, which in turn enhances the body’s overall antioxidant defence capacity. Research has shown puha to have three times the antioxidant activity of blueberries.

Anti-inflammatory:
Multiple constituents in puha work synergistically to reduce inflammation. Chlorogenic acid and caffeic acid inhibit the production of pro-inflammatory cytokines including interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumour necrosis factor-alpha (TNF-α), which in turn reduces systemic inflammation. Additionally, these compounds suppress the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), which in turn decreases the production of inflammatory mediators like prostaglandins and nitric oxide. The flavonoids stabilise cell membranes, which in turn reduces inflammatory cascade activation.

Digestive Tonic & Blood Purifier:
The bitter sesquiterpene lactones stimulate taste receptors on the tongue, which in turn triggers the cephalic phase of digestion and promotes the secretion of digestive enzymes, bile, and gastric juices. This enhanced digestive function improves nutrient absorption and relieves symptoms of sluggish digestion, which in turn supports the body’s natural detoxification processes. The mild choleretic effect stimulates bile flow from the liver, which in turn aids in the elimination of metabolic waste products and supports liver function.

Antimicrobial:
The phenolic compounds and sesquiterpene lactones disrupt bacterial cell membranes, which in turn increases permeability and leads to leakage of cellular contents and eventual cell death. Chlorogenic acid and caffeic acid have demonstrated activity against various pathogenic bacteria including Staphylococcus aureus and Bacillus cereus. The compounds also interfere with fungal cell membrane integrity, which in turn inhibits the growth of certain fungi.

Blood Sugar Modulation:
Chlorogenic acid and caffeic acid improve insulin sensitivity in cells, which in turn enhances glucose uptake and utilisation. These compounds modulate the expression of genes involved in glucose metabolism and inhibit α-glucosidase enzyme activity in the intestine, which in turn slows the breakdown of complex carbohydrates and reduces post-meal blood sugar spikes. This makes puha potentially supportive for individuals managing blood sugar levels.

Anti-ageing (Cellular Protection):
The combination of phenolic acids and flavonoids suppresses stress-induced premature cellular senescence by protecting cells from hydrogen peroxide (Hâ‚‚Oâ‚‚) damage, which in turn maintains cellular function and delays ageing processes. Puha extracts increase cellular antioxidant activity more effectively than isolated chlorogenic acid, which in turn demonstrates the synergistic benefits of whole-plant compounds. The caffeic acid derivatives activate the Nrf2 signaling pathway, which in turn increases the expression of protective antioxidant enzymes.

Mild Sedative & Nervine:
The lactucin derivatives and other sesquiterpene lactones have mild calming effects on the nervous system, which in turn helps reduce anxiety and promotes restful sleep. Traditional use suggests gentle nervine properties, though the mechanisms are not fully understood. The compounds may interact with GABA receptors, which in turn produces a subtle calming effect without significant sedation.

Nutritive & Restorative:
The rich nutrient profile, including high levels of vitamin C, provitamin A carotenoids, B-vitamins, and minerals, supports overall health and vitality. The combination of vitamins and antioxidants strengthens immune function, which in turn helps the body resist infection and recover from illness. The iron and B-vitamins support healthy blood formation, which in turn addresses mild nutritional anaemia and promotes energy levels.

Main Use

Puha’s main use is as a nutritive tonic and blood purifier, supporting overall vitality and digestive function. It is particularly valued for its exceptional antioxidant content and ability to support the body’s natural detoxification processes. Traditionally consumed as a nutritious green vegetable, puha combines food and medicine, providing essential nutrients while gently stimulating digestion and supporting liver function.

In traditional Māori practice, puha is used both internally for digestive complaints, as a general tonic, and to support recovery from illness, and externally for wound healing and skin conditions. The bitter principles make it especially useful for sluggish digestion, while its anti-inflammatory and antimicrobial properties support healing and immune function.

Preparations

Fresh Food: Young leaves eaten raw in salads or lightly steamed, boiled, or stir-fried like spinach. This is the traditional and most common preparation. The bitter juice can be squeezed out before cooking if desired, though it contains beneficial compounds.

Tea/Infusion: 2-3 teaspoons of dried leaf (or a small handful of fresh leaves) per cup of boiling water. Steep covered for 10-15 minutes. Drink 1-3 cups daily for digestive support and as a nutritive tonic.

Juice: Fresh leaves can be juiced (alone or with other greens) and consumed for concentrated nutrition and antioxidant benefits. Start with small amounts (30-60 mL) and dilute with water or other juices if needed.

Tincture: Fresh plant (1:2 in 60% alcohol) or dried plant (1:5 in 40% alcohol). Macerate for 2-4 weeks, strain. The bitter compounds and phenolic acids extract well in alcohol.

Decoction (root): 1-2 teaspoons of dried, chopped root per cup of water. Simmer gently for 15-20 minutes, strain. Traditionally used for deeper detoxification and as a blood purifier.

Poultice (topical): Fresh leaves crushed or pounded and applied directly to skin for minor wounds, boils, or skin irritations. The milky sap can be applied to warts and corns (use with caution as it is caustic).

Dosage

Fresh Leaves (food): 50-100g cooked as part of a meal, several times per week for nutritional benefits

Dried Herb (tea): 2-4g (approximately 2-3 tsp), infused, 1-3 times daily

Fresh Juice: 30-100 mL, 1-2 times daily, diluted if desired

Tincture (1:5, 40%): 2-5 mL, 3 times daily

Root Decoction: 1 cup, 1-2 times daily for short-term use (1-2 weeks)

Topical Use: Fresh crushed leaves applied to affected area 2-3 times daily; milky sap applied sparingly to warts (with caution)

Safety & Drug Interactions

Scientific Evidence

Antioxidant Activity: Multiple studies have confirmed puha’s exceptional antioxidant capacity. Research using DPPH, ABTS, and cellular antioxidant activity (CAA) assays has demonstrated that puha extracts have significantly higher antioxidant activity than many common fruits and vegetables, including blueberries. The major antioxidants identified are caftaric acid, chlorogenic acid, and chicoric acid.

Anti-ageing & Cellular Protection: In vitro studies on human fibroblast cells (WI-38) showed that puha leaf extracts suppress hydrogen peroxide-induced premature cellular senescence in a dose-dependent manner. At concentrations of 5-20 mg/mL, the extracts were as effective as or better than ascorbic acid in preventing stress-induced cell ageing.

Anti-inflammatory Effects: Animal studies and in vitro research have demonstrated that puha extracts and isolated compounds (particularly chlorogenic acid and caffeic acid) significantly reduce pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and suppress COX-2 and iNOS expression in LPS-stimulated macrophages. Oral administration in mouse models of sepsis showed marked reduction in systemic inflammation.

Blood Sugar Modulation: Recent research has shown that chlorogenic acid and caffeic acid from puha synergistically improve insulin sensitivity and modulate glucose uptake in hepatic (HepG2) cells. The compounds activate insulin signaling pathways and inhibit α-glucosidase activity, which in turn helps regulate post-meal blood sugar levels.

Antimicrobial Properties: In vitro studies have demonstrated antimicrobial activity against various bacterial and fungal pathogens, including Staphylococcus aureus, Bacillus cereus, and Aspergillus ochraceus. The phenolic compounds are thought to disrupt microbial cell membranes.

Nutritional Value: Chemical analysis confirms puha as a rich source of vitamin C (higher than many citrus fruits on a gram-for-gram basis), provitamin A carotenoids, B-vitamins, calcium, phosphorus, and iron. Captain Cook famously used puha to prevent scurvy among his crew due to its high vitamin C content.

Evidence Level: Strong traditional use over centuries (both in Māori culture and globally); growing in vitro and animal model evidence supporting antioxidant, anti-inflammatory, and metabolic effects; limited human clinical trials to date. The gap in clinical research does not indicate lack of efficacy but rather lack of research funding for traditional food plants.

Western Energetics

Temperature: Cooling. Puha’s bitter taste and ability to support liver function and reduce inflammation indicate its cooling nature. It is useful for conditions of excess heat in the body.

Moisture: Drying and clearing. The bitter constituents stimulate secretions initially (bile, digestive juices) but ultimately have a drying effect on damp, stagnant conditions. Useful for clearing excess moisture from tissues.

Tissue State: Primarily for Depression/Atrophy (sluggish digestion, stagnant liver function) and Heat/Excitation (inflammation, infection). The bitter tonic action addresses deficiency and stagnation, while the cooling anti-inflammatory properties address heat and irritation.

Taste

Bitter: The dominant taste, especially pronounced in older leaves and the milky sap. This bitterness indicates the presence of sesquiterpene lactones and other compounds that stimulate digestive secretions and support liver function. The bitter taste is central to puha’s therapeutic properties as a digestive tonic and blood purifier.

Slightly Salty: A subtle secondary taste that reflects the mineral content of the plant, particularly calcium and other electrolytes.

Mildly Astringent: A gentle drying quality that can be detected, particularly in the leaves, which supports the plant’s ability to tone tissues.

Plant Lore

Puha holds deep significance in Māori culture as a traditional food plant brought to Aotearoa over 1,000 years ago. While Sonchus oleraceus is the introduced species, it was readily adopted alongside the native Sonchus kirkii (raurīroa) due to similar properties and was given the same name. The famous dish “pork and puha” (or “boil-up”) remains a cherished traditional food that combines the bitter greens with meat (pork or eel traditionally) to create a nourishing, balanced meal.

Traditionally, Māori would gather puha from cultivated areas where it grew spontaneously, pound the stems to remove the bitter white juice (waiu), and either eat the stalks raw or cook them with meat in an earth oven (umu). Some people would leave the bitter juice in if they didn’t mind the taste, while others preferred to squeeze it out for a milder flavour. The leaves with holes (from insect feeding) were sometimes considered to have concentrated energy, similar to the traditional view of kawakawa leaves.

Puha was also used ceremonially in whakanoa rituals (removing tapu, or sacredness) and other traditional practices. The juice was used as a sizing agent for waka (canoes) before painting. Medicinally, the juice was drunk for haemorrhage in childbirth, and decoctions were used for expelling the placenta and treating boils.

In European tradition, the name “sow thistle” refers to its attractiveness to pigs, who would eagerly eat the plants. The Greek name Sonchus comes from an ancient word for hollow, referring to the hollow stems. The species name oleraceus means “vegetable” or “kitchen herb,” reflecting its long history as a pot herb. Ancient Greek and Roman texts mention sowthistles as both food and medicine, with Pliny the Elder describing their cooling and emollient properties.

The plant’s ability to thrive in disturbed ground and its rapid spread led to it being viewed as a weed in many agricultural contexts. However, this same vigour and resilience make it an accessible and reliable source of nutrition and medicine for those who recognise its value.

Additional Information

Puha is an excellent example of a plant that bridges the categories of food and medicine. Its exceptional nutritional density makes it valuable as a regular part of the diet, while its medicinal constituents provide therapeutic benefits that go beyond basic nutrition.

Distinguishing Species: In New Zealand, three Sonchus species are commonly found:

• Sonchus oleraceus (smooth sowthistle/puha) – smooth, non-prickly leaves with a dusky blue-green colour
• Sonchus asper (prickly sowthistle) – leaves with spiny margins; slightly different chemistry but similar uses
• Sonchus kirkii (raurīroa) – native New Zealand species, perennial, more bitter than S. oleraceus

All three have similar properties and can be used interchangeably, though S. oleraceus is generally preferred for eating due to its milder flavour.

Cultivation Tips: While often treated as a weed, puha can be intentionally cultivated as a nutritious green:

• Grows quickly from seed (4-6 weeks to harvest)
• Harvest young leaves before flowering
• Can be grown as a cut-and-come-again crop
• Self-seeds readily – may become weedy if allowed to flower
• Tolerates partial shade, making it useful in intercropping
• Benefits from regular harvesting, which encourages tender new growth

Conservation & Foraging: Sonchus oleraceus is an abundant introduced species in New Zealand and foraging it helps control its spread. However, the native Sonchus kirkii (raurīroa) is less common and should be harvested conservatively. Always ensure correct identification and harvest from clean areas away from roadsides, sprayed areas, and contaminated ground.

Modern Research Directions: Current research is investigating puha’s potential in:

• Diabetes management and metabolic syndrome
• Anti-ageing and skin health formulations
• Functional foods and fortification
• Neuroprotective applications for cognitive health

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