Comfrey

Description

Comfrey is a perennial plant native to most of North America, Europe, and western Siberia. It is found in moist, watery places. The rootstock is fleshy, branched, and white internally. The plant produces an angular hairy stem which grows up to three feet in height, branching only near the top. It bears large, oblong, lanceolate leaves, which are green, rough, and covered with short hairs. Basal leaves are also present, usually lying along the ground. Whitish, pale purple flowers grow in racemes from the upper leaf axils, blooming from May to August. The fruit consists of four small nuts located at the bottom of the calyx.

Other common names for this plant are:

CHEMICAL COMPOSITION

NUTRIENT COMPOSITION

PROPERTIES AND USES

Anodyne - a substance which relieves pain, usually with accompanied sedation.

Astringent - an agent which causes the constriction or contraction of tissue.

Demulcent - an agent which smooths the mucous membranes on contact.

Diuretic - Diuretics form a class of drugs which increase the volume of urine produced by the kidneys. It can be used effectively to treat mild cases of edema when kidney function is good and when the underlying abnormality of cardiac function, capillary pressure, or salt retention is being corrected simultaneously. Diuretics are not an appropriate treatment for edema caused by inflammation of the kidneys, and are useless in cardiac edema associated with advanced kidney insufficiency.

Emollient - a skin dressing or soothing ointment.

Expectorant - an agent which stimulates the outflow of mucus from the lungs an bronchials.

Hemostatic - any drug, medicine, or blood component that serves to stop bleeding.

Refrigerant - an agent which alleviates heat, fever, or thirst.

Vulnerary - any form of first aid for wounds and skin abrasions.

Comfrey is one of the most valuable herbs known to botanic medicine because it has beneficial effects on all parts of the body, and can be used as an overall tonic. It has been successfully used for centuries as a wound-healer and bone-knitter, strengthening the skeleton and the pituitary gland. Comfrey helps in the calcium-phosphorus balance by promoting strong bones and healthy skin. It helps promote the secretion of pepsin and is a general aid to digestion. It is one of the finest healers for the respiratory system, and can be used internally and externally. Comfrey has been used with great success to check hemorrhage from the stomach, lungs, bowels, kidneys, and piles.

Comfrey root works longer in the intestines than does pepsin. Comfrey root's mucilage helps heal ulcers by coating them and destroying amoebic parasites.

Laboratory studies done in India have shown that the mucilage in herbs like comfrey root act as a strong deterrent to Escherichia coli and similar intestinal microorganisms by absorbing them and other toxins.

According to British scientific studies, comfrey has seven times more protein than does soybeans and eight times more carbohydrates. Comfrey root is extremely mucilaginous; it has more mucilage than does marshmallow root. Comfrey root has between 0.6-0.8% allantoin and a large percentage of natural plant gum. Comfrey root's mucilaginous properties work on the lungs in the same manner as in the colon.

TOXICITY FACTORS

Comfrey contains two alkaloids which, when taken in sufficient quantities, have produced depression in the central nervous system. Comfrey may be contraindicated in patients on dietary potassium restrictions. Considerable amounts of allantoin are present in the root and leaves, but it is virtually nontoxic. At least eight pyrrolizidine alkaloids have been identified in the leaves of Russian comfrey (S. uplandicum): echimidine, symphytine, locopsamine, intermedine, acteylcopsamine, acetylintermedine, symlandine, and angelyl 9 echimidinylretronecine. Some, but not all pyrrolizidine alkaloids cause liver damage. Several reports of pyrrolizidine alkaloid poisonings in humans cited both liver and lung damage.

In another study conducted with several groups of inbred strain ACI rats of both sexes, the incidence of liver tumors was higher in those groups fed a diet containing comfrey root than in those fed a diet containing comfrey leaf, even though the percentage of comfrey flour is higher in the leaf diet than in the root diet. Furthermore, rats became seriously affected when roots were fed in a concentration of 4% in two groups of rats, whereas rats tolerated the feeding of the leaves. However, rats in one groups could ingest an 8% diet of roots without more serious toxic effects compared with those in another group given only a 4% diet. This suggests that comfrey toxicity can be varied, even though plant material was collected in the same area and at the same time.

Poisoning can result when foxglove or digitalis is mistaken for comfrey and inadvertently consumed. Symptoms were weakness, nausea, envisioning yellow halos around objects, and poisoning, sometimes resulting in death.

Recently the Australian government banned the sale and use of comfrey in herbal medications due to a fear of toxic factors.

DRUG PRECAUTIONS AND INTERACTIONS

Any of the following drugs may be imperfectly absorbed if comfrey is being used on a daily basis: tetra- cycline derivatives, oral anticholinergics, phenothiazines, digoxin, isoniazid, phenytoin, and warfarin.

The urinary excretion of alkaline drugs, such as amphetamines or quinidine, may be inhibited by the antacid nature of comfrey. The antacid nature of comfrey may also decrease or delay the absorption of nalidixic acid and the sulfonamides.

The antituberculous activity of comfrey may potentiate the adverse effect of other antituberculous drugs, especially ethionamide.

The anti-inflammatory activity of comfrey can be seriously inhibited by phenobarbital and certain other sedatives and hypnotics, such as chloral hydrate and meprobramate. This is also true of beta-adrenergic blocking agents, such as propranolol.

The topical application of the astringent herb comfrey, in conjunction with the acne product tretinoin (retinoic acid, vitamin A acid), may adversely affect the skin.

The antacid properties of comfrey may enhance the renal tubular resorption of the antiarrhythmic drug quinidine, leading to increased quinidine serum levels.

To the extent that comfrey's action depends on the presence of cholinergic substances, its action will be affected by the decrease in cholinergic-receptor stimulation produced by anticholinergics.