Blessed Thistle

Scientific Name(s): Cnicus benedictus
Common Name(s): Cardin, Carduus benedictus, Holy thistle, Spotted thistle, St. Benedict's thistle

Medically reviewed by Drugs.com. Last updated on Oct 22, 2021.

Clinical Overview

Use

Blessed thistle has been traditionally used to stimulate secretion of gastric juices and saliva, to increase appetite and facilitate digestion, and to stimulate the flow of bile. It is a common ingredient in combination formulas for gastric health. Anti-inflammatory, antimicrobial, and cytotoxic activities have been reported and thought to be due to the chemical constituent cnicin. However, there are no clinical trials to support these potential uses.

Dosing

No clinical studies exist to provide dosing recommendations for blessed thistle. Doses of 4 to 6 g daily have been traditionally used.

Contraindications

Blessed thistle is contraindicated in patients with gastric ulcers or other inflammatory bowel conditions, such as Crohn disease.

Pregnancy/Lactation

Avoid use. Blessed thistle should not be used in pregnancy. Information regarding safety and efficacy in lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Allergy and cross sensitization have been reported with other members of the Asteraceae family. Stimulation of gastric acid secretion has been reported. Emesis is likely with high dosages.

Toxicology

Clinical information is limited. Emesis is likely with high dosages (5 g or more).

Scientific Family

• Asteraceae (daisy)

Botany

Blessed thistle is native to southern Europe, western Asia, and North Africa, and has been naturalized throughout the United States and Europe. It is considered a noxious weed and grows mostly in stony, uncultivated areas. It is an annual, growing about 0.7 m in height with leathery, hairy leaves 30 cm long and 8 cm wide. The entire plant is covered with down and bears pale yellow flowers in dense, prickly flower heads. Blessed thistle should not be confused with Silybum marianum, which is commonly referred to as "milk thistle."Duke 2002, Khan 2009, Ulbricht 2008, USDA 2016 Synonyms are Centaurea benedicta and Cirsium pugnax.

History

The plant was widely cultivated during the Middle Ages in Europe and was used in many herbal formulations of the period.Blumenthal 2000 Its medicinal use as a healing herb was mentioned by Shakespeare in his play Much Ado About Nothing.Shakespeare 1914 It was thought to be useful against the bubonic plague; however, its main uses were for treatment of digestive complaints, gout, fever, and headache.Duke 2002, Khan 2009 Blessed thistle was also recommended as an emmenagogue and galactogogue, and for the treatment of intestinal worms.Duke 2002, Khan 2009 The plant's dried leaves, stems, and flowers have been used medicinally. Blessed thistle, used in flavoring Bénédictine liqueur, has generally recognized as safe (GRAS) status as a flavoring agent. It is available as a single herb and in homeopathic preparations. Blessed thistle is approved by the German Commission E for treatment of dyspepsia and loss of appetite, and is a minor component of a multiherb cancer remedy formulation.Blumenthal 2000

Chemistry

The most prominent constituent of blessed thistle is the bitter sesquiterpene lactone ester cnicin. The leaves and plant parts contain tannins, sesquiterpenes, a high mineral ...