Red clover (Trifolium pratense) is a familiar meadow herb, one of 250 species in the Leguminosae, or pea family. The Irish shamrock is another species in this family of plants. Red clover is a European native naturalized throughout North America and Canada. This familiar short-lived perennial grows wild along roadsides, in meadows, and in fields, and is extensively cultivated as a forage crop for cattle. It grows best in soils that are rich in calcium, potassium, and phosphorus. The common names for this sweet herb include wild clover, meadow trefoil, bee bread, trefoil, cow grass, purple clover, and three-leafed grass.
Red clover grows to about 2 ft (61 cm) high from a short, woody rootstock. The leaves are palmate and arranged alternately along the round, grooved, and hairy stem. They are divided into three oblong or oval leaflets, a characteristic that has given the genus its name. The dark green leaves often have a splash of a pale green or white on each leaflet. The leaf margins are toothed. The red-purple or magenta-hued blossoms comprise numerous florets that form a globe-shaped flower on the end of the stalk. Red clover blooms throughout the summer. The edible blossoms are sweet-tasting with a honey-like fragrance. Bees are attracted to clover blossoms, but seem to prefer the white blossoms of another common variety of clover, often growing nearby.
In folk tradition, red clover was associated with the Christian doctrine of the Trinity because of its threefold leaflets. In England it was worn as a magic charm to protect against evil. The herb's value as a medicinal remedy was not well known until the herb made its way to North America. Native American herbalists soon found numerous medicinal uses for this common wayside beauty. Red clover was used as a cancer treatment; the blossoms, combined with other herbs, became commercially popular in the United States in the 1930s. Numerous so-called "Trifolium Compounds" were marketed as blood purifiers, or alteratives, to help clear the body of metabolic toxins. The herb was listed in the National Formulary of the United States until 1946.
Red clover has most often been used to treat such skin inflammations as psoriasis and eczema. It also acts as an expectorant and demulcent, and is helpful in the treatment of bronchitis and spasmodic coughs, particularly whooping cough. Red clover may stimulate the liver and gall bladder and has been used for constipation and sluggish appetite. The blossoms were smoked as a remedy for asthma. An infusion of red clover blossoms used as a skin wash, or a poultice prepared from fresh blossoms, may relieve the irritation of athlete's foot or insect bites. The infusion is also useful as an external skin wash in the treatment of persistent sores and ulcers,
and may help speed healing. As an eyewash, red clover tincture diluted with fresh water may relieve conjunctivitis. An ointment prepared from red clover is helpful for lymphatic swellings, and a compress made with it may relieve the pain of arthritis and gout. More recently, red clover has been studied as an alternative remedy for hot flashes in menopausal women as well as hot flashes in men following surgery for prostate cancer.
Many of the chemical constituents present in red clover have been identified, including volatile oil, isoflavonoids, coumarin derivatives, and cyanogenic glycosides. Few scientific studies, however, have confirmed the folk use of red clover remedies. The genistein found in red clover has been found to contribute to the shrinking of cancerous tumors in vitro by preventing growth of the new blood vessels that feed the tumors. One of the first studies using purified extract of red clover, published in 1999, concluded that use of red clover in standardized extracts that include specific quantities of the four isoflavones genistein, daidzein, biochanin and formononetin, resulted in improved heart health in postmenopausal women. Red clover is considered by some herbalists to be a phytoestrogenic herb, useful in restoring estrogen balance in women. The chemical formononetin, found in red clover, acts on the body in a similar way as estrogen.
Red clover blossoms are the medicinally active part of this herb. Fully open blossoms can be harvested throughout the flowering season. Pick the flower heads on a sunny day after the morning dew has evaporated. Spread the blossoms on a paper-lined tray to dry in a bright and airy room away from direct sun. The temperature in the drying room should be at least 70°F (21°C). When the blossoms are completely dry, store dried flowers in a dark glass container with an air-tight lid. The dried herb will maintain medicinal potency for 12–18 months. Clearly label the container with the name of the herb and the date and place harvested.
Tincture: Combine 4 oz of fresh or dried red clover blossoms with 1 pint of brandy, gin, or vodka in a glass container. The alcohol should be enough to cover the flowers. The ratio should be close to 50/50 alcohol to water. Stir and cover. Place the mixture in a dark cupboard for three to five weeks. Shake the mixture several times each day. Strain and store in a tightly capped, clearly labeled dark glass bottle. A standard dose is 1–3 mL of the tincture three times a day. Tinctures properly prepared and stored will retain medicinal potency for two years or longer.
Infusion: Place 2 oz fresh clover blossoms, less if dried, in a warmed glass container. Bring 2.5 cups of fresh nonchlorinated water to the boiling point and add it to the herbs. Cover the tea and steep for about 30 minutes, then strain. Drink cold, a few mouthfuls at a time throughout the day, up to one cup per day. The prepared tea may be kept for about two days in the refrigerator.
Ointment: Add fresh clover blossom to a glass pan of nonchlorinated water. Simmer on low heat or in a crock pot for two days. Strain. Allow most of the water to evaporate and combine the plant extract with an equal amount of melted beeswax. Pour while warm into small airtight containers.
Red clover is a safe and mild remedy. No adverse effects have been reported in humans when taking therapeutic doses of the herb. Allergic reactions to red clover are rare but possible. Numerous reports of toxicity, even death, however, have been reported in cattle who overgraze in fields of clover.
No side effects in humans have been reported for nonfermented red clover. Fermented extracts of red clover, however, may cause bleeding.
No interactions have been reported between red clover and other herbs. It has, however, been reported to have adverse interactions with certain allopathic medications, particularly heparin, ticlopidine, and warfarin. Red clover also reduces the body's absorption of combined estrogens.
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Rebecca J. Frey, PhD