Very preliminary studies suggest that cat’s claw may help immune function.
Have you noticed the outbreak of news coverage on infectious diseases lately? It’s easy to think we live in a sea of vicious bugs, ever ready to attack.
The human immune system might be our most important defense for living in the modern world. In recent decades, scientists have become increasingly interested in immunity as a hot topic for research. As the body of studies grows, more of the benefits of traditional immune-enhancing herbs are confirmed.
During this year’s cold and flu season, you may begin to see a few newcomers on health-food store shelves. You may also hear about new research confirming healing properties of your old favorites.
Berberine has been a hot research topic lately. More than sixty scientific studies were published on this chemical in 1999 and the first half of 2000 alone.
A newcomer to the immune scene
Long revered in Traditional Chinese Medicine (TCM), andrographis (Andrographis paniculata) is just beginning to get attention in the United States. Also known as chuan xin lian, the herb grows as a wild, annual shrub in Asia. It has been used historically to treat colds, fevers, bronchitis, diarrhea, worms, and liver disorders.
Andrographis has been researched extensively. At least fifty-eight scientific studies of the herb have been published since the 1970s for male birth control, diabetes, cardiovascular benefits, and for immune-stimulating and antioxidant properties. The bulk of the findings point to the herb’s actions as an immune booster and as a liver protectant.
The main constituent responsible for these actions seems to be andrographolide. This compound and related ones have cooling and anti-inflammatory effects.
A 1999 study from Chile showed that people with colds may benefit from taking andrographis. Researchers gave 158 people the herb in a dose of 1,200 mg of dried extract per day. Then they measured the subjects’ symptoms of headache, tiredness, earache, sleeplessness, sore throat, nasal secretion, phlegm, and frequency and intensity of cough. At day four, the people taking andrographis experienced a 95 percent decrease in the intensity of all of their cold symptoms.
An earlier Thai study of 152 patients with inflammation of the pharynx and tonsils found that treatment with andrographis for a week was as effective as treatment with acetaminophen in providing relief of fever and sore throat.
Andrographis has been used for more than twelve years in Scandinavia for reducing the symptoms and duration of colds. A double-blind, placebo-controlled Swedish study treated fifty patients in the early stages of a cold with an herbal preparation containing 85 mg of andrographis extract three times daily. After five days, 68 percent reported complete recovery, compared to only 36 percent in the group that took a placebo. In the treated group, 55 percent characterized their colds as unusually mild. These patients also took less sick leave from work.
Based on the historical and scientific evidence for andrographis’ effect on the immune system, researchers think the herb might have some benefit for HIV patients. A 1991 test-tube study from the University of California at Davis found that a compound made from andrographis inhibited the spread of the virus among cells.
In 2000, an initial study was undertaken to investigate this possibility. Researchers from Bastyr University in Seattle gave the herb to thirteen HIV-positive patients and five HIV-uninfected, healthy volunteers. In this very preliminary study, andrographis produced a significant rise in one marker of increased immune function.
Andrographis is gradually finding its way into combination herbal products in North America. Look for it in combination with other immune-enhancing herbs such as echinacea, lemon balm, slippery elm bark, cinnamon bark, and Chinese fritillary bulb. If you use it by itself, a typical dose is 1 to 6 g per day of dried herb, or up to 20 ml per day of the tincture. So far, there are no cautions known about taking andrographis.
Elder flower and berry (Sambucus nigra)
Elder flower is a renowned fever reducer that has been a mainstay in European herbal cold treatment. Combined with gentian root (Gentiana lutea), it forms the basis of a well-known European herbal formula for sinus infections. Since 1972, at least eight scientific studies have shown beneficial results from these two herbs when combined with cowslip flower (Primula veris) and sorrel (Rumex acetosa), herbs that liquefy mucus and enhance drainage, and vervain (Verbena officinalis), another anti-inflammatory.
A randomized, placebo-controlled study done in Freiburg, Germany, in 1999 compared this blend of herbs with the use of an antibiotic drug and a decongestant for the treatment of viral sinus infections. The herbs produced faster response, greater effect, and a lower prevalence of side effects.
Echinacea (Echinacea spp.)
Echinacea has been one of the top-selling herbal remedies ever. But there has been some conflicting data on whether it works and, if so, how well and for which conditions.
A 2000 study published in Pharmacotherapy evaluated the existing scientific literature on echinacea. Although results were unclear due to flaws in the design of the study evaluated, twelve clinical studies published from 1961 to 1997 concluded that echinacea effectively treated the common cold. Out of five trials published after 1997, three concluded that the herb reduces the frequency, duration, and severity of common cold symptoms.
In 1999, a German experiment demonstrated the positive effect of a combination formula containing echinacea. This randomized, double-blind, placebo-controlled study of the common cold used a blend of echinacea root, baptisia root, and thuja leaf. A total of 263 patients saw doctors at fifteen different study centers. They took the combination three times a day for seven to nine days. Then the patients documented the daily intensity of eighteen cold symptoms, as well as how they felt overall, using a ten-point scale. Among patients with at least moderate symptom intensity, 55.3 percent in the herbal remedy group showed improvement, compared to only 27.3 percent in the placebo group.
From these studies, it seems reasonable to conclude that echinacea can help you kick a cold once you’ve got one. But among experts, there is considerable debate about whether echinacea prevents viral diseases.
Recently, a group of researchers from Montreal added to the evidence that echinacea may play a preventive role. These researchers put echinacea in the food of mice for two weeks. Their 1999 report showed that levels of two types of virus-fighting cells increased in the mice one week into treatment. The fact that such cells were elevated in the bone marrow of the mice indicates that at least one action of this herb is to stimulate new cell production. The significant elevation of these two fundamental immune cells appears to suggest a preventive role for this herb, according to the scientists.
Echinacea appears to be safe; however, individuals who are allergic to ragweed may experience allergic reactions to echinacea.
The plant alkaloid berberine, found in several herbs including Oregon grape root (Mahonia aquifolium), barberry (Berberis vulgaris), Chinese goldthread (Coptis chinensis), and goldenseal (Hydrastis canadensis) has a long history of medicinal use by Ayurvedic and TCM practitioners as well as Native American herbalists. Berberine-containing herbal preparations have demonstrated significant antimicrobial activity against a variety of organisms including bacteria, viruses, fungi, protozoa, and intestinal para- sites. Today, it’s mainly used for cases of bacterial diarrhea, intestinal parasite infections, and chronic bacterial conjunctivitis.
Berberine has been a hot research topic lately. More than sixty scientific studies were published on this chemical in 1999 and the first half of 2000 alone. Evidence has been accumulating that berberine might be valuable in the treatment of various types of cancer cells.
While definitive human studies are lacking, test-tube studies point to several potential uses for this herbal compound. A Japanese study published in 2000 indicates that Chinese goldthread and/or berberine may benefit esophageal cancer. In the test tube, both substances were potent inhibitors of cancer cells. An earlier study from Taiwan revealed that berberine inhibited—and at higher doses killed—human colon cancer cells in laboratory cultures.
Herbalists commonly use berberine-rich plants to treat yeast infections. A study done in Italy established that berberine added to laboratory cultures inhibited the ability of infectious yeast to produce an enzyme it needs to colonize skin and other tissues.
Cat’s claw (Uncaria tomentosa)
A general tonic and anti-inflammatory from South America, cat’s claw burst onto the scene in North America and rapidly advanced from obscurity to become one of the more popular herbs in the United States. Scientific research is still trying to catch up. More than ten new studies have appeared in the past two years—before that there was almost nothing in the published research.
A new but very preliminary study done in 2000, published by Albany Medical College in Albany, New York, indicates that cat’s claw is not only an effective anti-inflammatory but also an antioxidant. Another report from Sweden, performed on both rats and humans, demonstrated that the herb increased immune function and enhanced DNA repair. After taking cat’s claw for six weeks, the four healthy male volunteers in the study had substantially increased white blood cell counts, a sign of enhanced immune response.
Chrysanthemum (Chrysanthemum ¥morifolium)
TCM practitioners consider chrysanthemum to be an immune booster, especially effective for feverish conditions of the upper respiratory tract. This herb has a history of test-tube studies suggesting that it may work against several bacteria, including strep, staph, and shigella. Test-tube studies have also shown that several compounds in chrysanthemum may inhibit the HIV virus.
Woad (Isatis tinctora)
This herb fights many types of viruses and bacteria. It is also used to reduce fever. A 1991 study showed that components from woad stimulate immune function in animal tissues. In 1996, a Danish group studied whether woad could heal lung infections in rats caused by the bacteria Pseudomonas aeruginosa. Compared to the control group, the herb was able to reduce lung abscesses and decrease the severity of the disease. In the great majority of the rats, the herb also reduced inflammation in the lungs.
Karta Purkh Singh Khalsa has more than twenty-five years of experience with medicinal herbs and specializes in Ayurvedic, Chinese, and North American healing traditions. He is a state-certified dietitian/nutritionist, a massage therapist, and a board member of the American Herbalists Guild.