This issue, learn about new studies on garlic, ginseng and castor beans.
A supplement to the Herb Companion from the American Botanical Council and the Herb Research Foundation.
Although numerous clinical studies, involving a total of thousands of subjects, have shown that garlic reduces cholesterol levels, a six-month double-blind, randomized study at Oxford University of 115 subjects ages thirty-five to sixty-four found no significant difference in cholesterol levels between the treatment and placebo groups at the end of the study. Those in the treatment group had received 900 mg of a garlic tablet standardized to 1.3 percent allicin three times daily. The results question the methodology of previous garlic studies. The researchers called for a rigorous, long-term trial of at least 1,000 subjects to determine whether garlic does in fact lower cholesterol.(1)
Traditionally, the roots of Asian ginseng (Panax ginseng), valued for their adaptogenic or tonic effects, have been considered of high quality only if they are at least four or five years old. A 1984 study showed that the highest yields of the primary active constituents, called ginsenosides (770 mg per root of Korean-grown Asian ginseng), are obtained at the end of the summer of the plant’s fifth year, as the root doubles in weight between the fourth and fifth years. After the fifth year, root size and ginsenoside content increased only slightly. Because of this finding, the roots are normally harvested in the fall of the plant’s fifth or sixth year.
In 1994, chemists with Agriculture and Agri-Food Canada measured the ginsenoside content of one-, two-, three-, and four-year-old roots of American ginseng (P. quinquefolius) growing in artificial shade. From the end of the third year to the end of the fourth year, the ginsenoside content increased from 4.74 percent of dried root weight to 7.83 percent. A 1995 trial yielded similar results, confirming that high-quality material should be at least four years old. Ontario is the leading producer of ginseng in North America, followed by Wisconsin and British Columbia.(2,3)
In the search for new contraceptives, researchers have been evaluating traditional methods throughout the world. A recent joint Jordanian/Saudi Arabian study found that feeding rabbits poisonous castor beans (Ricinus communis) prevented conception, although the mechanism of action and active compound have not been determined. Castor beans have been used as a contraceptive in many countries, including India and Korea. In Algeria, women dip a castor bean in warm rabbit blood before eating it. Egyptian women have been reported to eat one bean after childbirth in the hope of preventing pregnancy for at least nine months.
Of twenty-one female rabbits in the study that were fed a small amount of castor beans every day for ten days, 81 percent (seventeen rabbits) failed to become pregnant. But each also experienced diarrhea and weight loss. A constituent of the seed pulp called ricin, which interferes with protein synthesis, is one of the most toxic substances known, and the quantity of castor beans effective to prevent contraception in humans is close to the lethal dose. Some people have died after consuming as few as three beans. It’s definitely not an herb to experiment with.(4)
(1) Neil, H.A.W., et al. “Garlic Powder in the Treatment of Moderate Hyperlipidaemia: A Controlled Trial and Meta-analysis”. Journal of the Royal College of Physicians of London 1996, 30(4):329–334.
(2) Soldati, F., and O. Tanaka. “Panax ginseng: Relation between Age of Plant and Content of Ginsenosides.” Planta Medica, 1984 50:351–52.
(3) Court, W. A., et al. “Influence of Root Age on the Concentration of Ginsenosides of American Ginseng (Panax quinquefolius)”. Canadian Journal of Plant Sciences 1996, 76(4):853–855.
(4) Salhab, A. S., et al. “On the Contraceptive Effect of Castor Beans”. International Journal of Pharmacognosy 1997, 35(1):63–65.
“Herbs for Health” is offered bimonthly by the American Botanical Council and the Herb Research Foundation as a supplement to The Herb Companion. Editor, Steven Foster
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“Herbs for Health” is intended as an educational service, not a source of medical advice or a guide for self-medication. Please consult a qualified health-care professional for treatment of any serious health problems. For further information on any of the topics in “Herbs for Health”, write the
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