Herbs for Health: Natural Cold and Flu Prevention

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American ginseng
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Cayenne peppers
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Purple coneflower
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Slippery elm
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Echinacea cultivation, Trout Lake Farm, Washington
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Asian ginseng
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Marsh mallow
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Milk thistle
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Dried cayenne peppers

It’s cold and flu season again. The cascade of symptoms that may accompany these acute viral infections of the upper respiratory tract includes stuffy and dripping nose, sneezing, lung congestion, coughing, sore throat, pressure headache, muscular ache, fever, and possibly gastrointestinal distress. Left alone, most cold and flu symptoms generally abate within five to seven days, although some, such as congestion or cough, may last for as long as two weeks.

Unfortunately, there is still no known cure for these most common of ailments. However, if we look at both traditional use and the scientific literature, we find several herbs that may help reduce the severity and duration of cold and flu symptoms, and at least one that even seems to help prevent the infections.

How Do You Spell Relief?

Herbs traditionally used to relieve cough symptoms and soothe irritated mucous membranes include coltsfoot leaves (Tussilago farfara), mullein flower (Verbascum thapsus), marsh mallow root (Althaea officinalis), and slippery elm bark (Ulmus rubra). Today, the use of coltsfoot is discouraged because it contains liver-toxic pyr­ro­li­zidine alkaloids, and claims for mullein are not well substantiated. Marsh mallow, however, is officially recognized in Germany for its soothing action, and slippery elm bark is an ingredient of a few over-the-counter drugs in the United States.

Herbs traditionally used to help expel phlegm from the upper respiratory tract include thyme leaves (Thymus vulgaris), horehound leaves (Marrubium vulgare), licorice root (Glycyrrhiza glabra), and eucalyptus leaves (Eucalyptus globulus). All are recognized in Europe as expectorants but need further testing for official recognition in the United States.

Ephedra (Ephedra sinica), or ma-huang, which has been used in China for more than 5000 years to treat bronchial asthma and related conditions, may help relieve bronchial congestion from colds and flu. How­ever, people suffering from severe hypertension, glaucoma, hyperthyroidism, prostate enlargement, or coronary thrombosis should not use it. Members of the mint family, especially peppermint (Mentha ¥ piperita), have traditionally been used to help reduce fevers, but this use has not been tested scientifically. For a more comprehensive overview of herbs useful in symptomatic relief of colds and flu, see Varro E. Tyler’s treatment of the subject in Herbs of Choice: The Therapeutic Use of Phytomedicinals.

Echinacea in the Flu Season

Once obscure, echinacea now outsells all other dietary supplements, according to a poll of retailers and distributors of natural foods published in the May 1995 issue of Health Foods Business magazine. The editors attribute its popularity to its reputation as a cure for colds and flu.

Of the nine species in the genus Echinacea, a group in the daisy family (Compositae), three are used in products in the United States: E. angustifolia, E. pallida, and E. purpurea. The roots of both E. angustifolia, narrow-leaved purple coneflower native to western prairies, and E. pallida, a pale purple coneflower from the Midwest, are primarily harvested from the wild, although commercial cultivation of these species has begun. Both the roots and the flowering tops of fresh and dried plants of E. purpurea, the common garden flower and another midwestern native, are used, and the entire world’s commercial supply is cultivated. It was developed as a commercial medicinal species in Germany in the late 1930s, and so it’s not surprising that the lion’s share of pharmacological and clinical studies of echinacea has been done in Germany on this species.

Clinical Studies

Echinacea is an immuno­stimulant–that is, it helps the body defend itself against minor viral infections, such as colds and flu, through a complex series of stimulating mechanisms within the immune system. This nonspecific immunostimulatory action fades relatively quickly, however, requiring repeated doses to sustain the effect.

A number of recent clinical studies in Europe have focused on the use of echinacea to reduce the symptoms associated with colds and flu and to prevent these infections. In a double-blind, placebo-controlled study of 180 volunteers, German researchers in Limberg and Bausendorf found that an alcohol extract of E. purpurea root helped lessen both the severity and the duration of such flu symptoms as nasal inflammation, swelling of the lymph glands, and coated tongue. Volunteers who received the equivalent of 900 mg per day of the extract showed statistically significant improvement in symptoms within three to four days compared with the placebo group and another group of patients who received half that dose.

Another German study, published in 1992, looked at the effect of a fresh juice extract of E. purpurea on the course and severity of cold and flu symptoms in patients deemed to have greater susceptibility to infections (as predetermined by T-cell ratios in the blood). Of 108 patients treated over an eight-week period, half received 2 to 4 ml per day of the extract. Compared with the placebo group, the treatment group had milder symptoms, fewer and briefer infections, and a longer period between infections.

These studies suggest that echinacea preparations can help prevent colds as well as reduce their severity and duration. Even with my less-than-perfect life­style, I find that if I take 2 teaspoons of echinacea alcohol ­extract every four hours as soon as I feel that I’m coming down with a cold or flu and for a ­couple of days thereafter, I’m able to bypass a full-blown ­infection.

Further Reading

• Bräunig, B., et al. Zeitschrift für Phytotherapie 1992, 13:7-13
• Foster, S. Echinacea: Nature’s Immune Enhancer. Rochester, Vermont: Healing Arts Press, 1991.
• Schöneberger, D., S. M. Klein (trans.). Forum Immunologie 1992, 8:2-12.
• Tyler, V. E. Herbs of Choice: The Therapeutic Use of Phytomedicinals. Binghamton, New York: Pharmaceutical Products Press, 1994.
• Wagner, H., and A. Proksch. In Economic and Medicinal Plant Research, edited by H. Wagner, H. Hikino, and N. R. Farnsworth, 1:113-155. Orlando, Florida: Academic Press, 1985.

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