Latin Name: Cnicus benedictus

Family: L. Asteraceae (daisies)

Common Names: Holy thistle , St. Benedict's thistle , cardin , spotted thistle , carduus benedictus, Cardo Santo,

Chemical: The most prominent constituent of blessed thistle is the bitter sesquiterpene lactone ester cnicin. Other germacrane sesquiterpenes include salonitenolide and artemisiifolin. The bitter lignans arctiin, arctigenin, and nortracheloside are also present. Two C13 polyacetylenes have been isolated as well. A patent discloses antifungal proteins active against plant pathogenic fungi, isolated from the seed of blessed thistle.

Note: Blessed thistle should not be mistaken for milk thistle ( Silybum marianus ) or other members of the thistle family.

Blessed Thistle is the sole species in the genus Cnicus, a thistle-like plant in the family Asteraceae, native to the Mediterranean region, from Portugal north to southern France and east to Iran. It is known in other parts of the world, including parts of North America, as an introduced species and often a noxious weed.

It is an annual plant growing to 60 cm tall, with leathery, hairy leaves up to 30 cm long and 8 cm broad, with small spines on the margins with pale yellow, prickly flowers. The whole plant is covered with down. The flowers are yellow, produced in a dense flowerhead (capitulum) 3-4 cm diameter, surrounded by numerous spiny basal bracts. The related genus Notobasis is included in Cnicus by some botanists; it differs in slender, much spinier leaves, and purple flowers.

The plant was widely cultivated in the Middle Ages in Europe. Its medicinal use was mentioned by Shakespeare in his play Much Ado About Nothing and was prominent in many of the herbals of the period. It was thought to be useful in treating plague; however, its main uses were for digestive complaints, gout, fever, and headache. Blessed thistle also was recommended as an emmenagogue, galactogogue, and abortifacient. (see Glossary)The dried leaves, stems, and flowers are used medicinally.

It is used in flavoring Benedictine liqueur and has GRAS (generally recognized as safe) status for alcoholic beverage use only. Blessed thistle has been used as a secondary component of the polyherbal alternative cancer treatment Flor Essence (Flora Manufacturing and Distributing, Inc.). It is available as a single herb and in homeopathic preparations. Blessed thistle was approved by the German Commission for treatment of dyspepsia and loss of appetite.

Blessed thistle is used to stimulate secretion of gastric juices and saliva, to increase appetite and facilitate digestion, and to stimulate the flow of bile. It has been used as a minor component of the alternative cancer remedy Flor-Essence and has antibacterial and antifungal activity. Other pharmacologic activities for blessed thistle include blockade of gonadotropin and anti-inflammatory properties. However, there are no reported human clinical trials for any of these uses

It has sometimes been used as a galactogogue to promote lactation. The crude drug contains about 0.2% cnicin. It is recommended for use by public health nurses in Ontario, Canada, as well as by the Canadian Breastfeeding Foundation along with Fenugreek to increase lactation in nursing mothers. It is a component in Bitters formulas, which are used to treat digestive issues. Blessed thistle may also be included in the unproven anti-cancer herbal remedy Essiac. This herb has been tested in laboratory studies for its properties against infections, cancer, and inflammation with promising results. However, high-quality trials showing benefits in humans are lacking.

There are no clinical studies to justify dosing of blessed thistle. Traditionally, 4 to 6 g of blessed thistle is used daily. Because of its irritating effect, blessed thistle is contraindicated in gastric ulcer or in inflammatory bowel conditions such as Crohn disease.

At high single doses (5 to 6 g) blessed thistle is known to be emetic. People sensitive to the sesquiterpene lactones of other asteraceous plants should use blessed thistle with caution. Blessed thistle extract was strongly sensitizing in a study of 12 species in the family Asteraceae