Ginseng, American

Panax quinquefolius L.

[Fam. Araliaceae]

Overview

Ginseng is one of the most widely used medicinal herbs with at least six species used in traditional systems of medicine. Most world production and trade of ginseng involves two species: Asian ginseng (Panax ginseng) and American ginseng (P. quinquefolius) (AAFC, 2000). According to TRAFFIC USA (the division of the World Wildlife Fund that monitors the status of threatened and endangered species), no other plant better represents the cultural and economic value of medicine harvested from the wild in North America than American ginseng (Robbins, 1997). The U.S. Department of Commerce (USDOC) measures ginseng production separately from other herbs due to its significant economic value. The U.S. exports up to two million pounds of cultivated ginseng roots annually (USDOC, 1995; USFWS, 1999a) and approximately 132,000 pounds of wild ginseng, primarily to China (Robbins, 1997; USDOC, 2000). Wisconsin produces 97% of all U.S.-grown ginseng. In 1998, Canada produced over 60% of the world supply of American ginseng (approximately four million pounds annually), the U.S. produced approximately 30%, and China produced the balance (approximately 7%). China remains the largest consumer of American ginseng (Xiao, 2000).

Native to North America, American ginseng is used in traditional indigenous medicine, particularly by the Cherokee, Creek, Iroquois, Menominee, Ojibwa, Pawnee, and Seneca tribes (Foster, 1999; Heffern, 1976; Moerman, 1998). In 1718, Canadian Jesuits began organizing the collection of American ginseng from the wild for export to China (Rafinesque, 1830), where in 1765, during the Qing dynasty, it was added to the Supplement to the Grand Materia Medica (a.k.a., Omissions from Ben Cao Gang Mu), by Zhao Xuemin (Bensky et al., 1986; Foster and Chongxi, 1992). American ginseng (xi yang shen) has since become integrated into Traditional Chinese Medicine (TCM) with indications for use distinctly different from those of Asian ginseng (ren shen) (Awang, 1998; Xiao, 2000). American ginseng became official in the United States Pharmacopeia (USP) in 1842. It was removed from the USP in 1882, but its popular use by American Eclectic medical doctors and homeopaths continued (Felter and Lloyd, 1898; Foster, 1999; HPUS, 1992; Millspaugh, 1892; Scudder, 1891). Its primary use was as a stomach tonic, though it was also used for nervous exhaustion from overwork (Felter and Lloyd, 1898; Scudder, 1891). By the late 19th century, American ginseng was already a threatened species due to overcollecting, and extensive cultivation efforts began (Millspaugh, 1892; USFWS, 1977; Wood et al., 1926). In 1947, the cultivation of American ginseng also began in China, but did not become large-scale until 1980 (AAFC, 1998; Xiao, 2000). American ginseng consumption in the U.S. trails far behind that of Asian ginseng and eleuthero (previously called Siberian ginseng, Eleutherococcus senticosus). Besides being sold as a dietary supplement, American ginseng’s primary use is as an ingredient in beverages. Compared to the scores of clinical trials on Asian ginseng, few clinical studies have been conducted on American ginseng (see table below). Each species of ginseng has similar but distinct chemical profiles, and therefore exhibits
different pharmacological and clinical activity.

Description

American ginseng root consists of the mature, dried, (usually) cultivated root of Panax quinquefolius L. [Fam. Araliaceae], harvested in the fall, separated from rhizomes, dried at low temperature, and containing no less than 1.0% of ginsenoside Rb1 as determined by HPLC (PPRC, 2000). American ginseng is harvested usually after a minimum of five years growth, although many roots cultivated in North America are harvested after four years. The highest-quality dried roots break with a somewhat soft and waxy fracture, while immature or undersized roots dry hard and glassy (USDA, 1978). Plant maturity can be determined before harvesting using two methods: counting the number of leaves (a.k.a., prongs) and/or removing soil where the stem joins the root to count the number of bud scale scars on the root. A single scar is produced every autumn after the plant’s stem falls (USFWS, 1999b). In December 1998, China issued quality control standards for American ginseng and its products entitled Grade and Quality Standards of Products of Processed American Ginseng (State Standard of People’s Republic of China, 1998).

Primary Uses

Endocrinology

Reduces postprandial glycemia in non-diabetics and type 2 diabetes patients (Vuksan et al., 2001, 2000a, 2000b)

Other Potential Uses

Sports Medicine

May improve cardio-respiratory endurance during submaximal work (reduced ventilation and increased oxygen consumption ability) (Goode et al., 1993)

Cognition

May improve mood-fatigue, may improve proofreading error detection (Johnson et al., 1980)

Traditional Chinese Medicine (TCM)

Deficiency of qi (diminished function of the internal organs and lowered body resistance); deficiency of yin (lack of body fluid, vital essence and blood, often resulting in endogenous heat); internal-heat (heat syndrome typically manifested by fever, night sweating, thirst, and constipation); cough and asthma; phlegm mixed with the blood; dysphoria and tiredness; diabetes; dry mouth and throat (PPRC, 2000). (These are terms and concepts used in TCM and may not always be correlated easily to Western biomedical terminology.)

Dosage

Internal

Crude Preparations

Decoction: 3–6 g dried root simmered in 720–960 ml water for approximately 45 minutes (PPRC, 2000; Yen, 1992). Other sources recommend simmering 2–9 g (Bensky et al., 1986; Foster and Chongxi, 1992).

Infusion: 150–240 ml boiling water poured over 1–2 g cut, dried root and steeped for 20 minutes (Xiao-fan and Liscum, 1996).

Root powder (dry): 1–3 g in capsules 40 minutes prior to meal for normalization of blood sugar in postprandial glycemia with or after meal (Vuksan et al., 2001).

Whole Root Powder: 3 g daily for postprandial glycemia in type 2 diabetes mellitus (Vuksan et al., 2000a).

Dry Extract: 330 mg, 3 times daily for improving physical endurance during work (Goode et al., 1993).

Duration of Administration

According to previous Eclectic medical use, American ginseng does not have an immediate effect and short-term use provides little benefit. Thus, continued use over an extended period of time is usually recommended (Felter and Lloyd, 1898). However, recent clinical trials have demonstrated an almost immediate effect in blood sugar metabolism when taken before meals (Vuksan et al., 2001, 2000a).

Chemistry

American ginseng has a chemical profile distinct from that of Asian ginseng. Its concentration of ginsenosides varies considerably depending on root age, month of harvest, method of drying, and method of analysis (Court et al., 1996; Reynolds, 1998). Studies identified 3.0–7.3% dammarane-type triterpene glycosides (saponins) including 1.22–1.6% ginsenoside Rb1, 0.02–0.27% ginsenoside Rb2, 0.18–0.29% ginsenoside Rc, 0.09–0.8% ginsenoside Rd, 0.9–1.1% ginsenoside Re, 0.12–0.2% ginsenoside Rg1; oleanolic acid derived ginsenoside: 0.1–0.25% ginsenoside Ro (Chuang et al., 1995; Li et al., 1996; Yen, 1992); 0.78% malonyl (m) ginsenosdes: 0.78% m-Rb1, 0.20% m-Rb2, 0.24% m-Rc, 0.14% m-Rd (Ren and Chen, 1999); dammarane-type triterpene oligoglycosides: quinquenosides I, II, III, IV, V (Yoshikawa et al., 1998); acetylenic alcohols: panaxynol, falcarindiol, panaxydol, and panaxytriol (Wang et al., 2000); a homodimeric protein quinqueginsin (Wang and Ng, 2000); and 0.04–0.97% volatile oil (Zheng et al., 1989).

Due to the potential adulteration of American ginseng with Asian ginseng in the marketplace, methods have been developed to differentiate the two species. For example, 24(R)-pseudo-ginsenoside-F11 is a characteristic constituent of American ginseng but occurs only in minute quantities in Asian ginseng, whereas ginsenoside-Rf is the characteristic constituent of Asian ginseng that is lacking in American ginseng (Chan et al., 2000; Dou et al., 1998; Shaw and But, 1995; Wenkui et al., 2000). Malonyl ginsenosides are found at much lower levels in Asian ginseng, at 10% total ginsenoside content compared to 40% total ginsenoside content in American ginseng (Awang, 2000). Thorough reviews of ginseng chemistry have been or will soon be published (Court, 2000; Chen et al., 2003).

Pharmacological Actions

Human

American ginseng whole root powder reduced postprandial glycemia in type 2 diabetes mellitus and in nondiabetic subjects (Vuksan et al., 2000a; 2000b). American ginseng root powder reduced glycemia in healthy individuals (Vuksan et al., 2001). American ginseng total extract demonstrated specific effect on the Fourier components of the radial artery pulse, confirming TCM descriptions (Wang et al., 1994), and increased respiratory endurance in exercise (Goode et al., 1993).

Traditional Chinese Medicine (TCM) Actions

Dispel wind (exogenous pathogenic factor with symptoms such as upper respiratory catarrh with headache and urticaria) and remove heat (symptoms such as fever, flushed face, thirst); relieve cough and resolve phlegm (secretions of the respiratory system) (PPRC, 2000).

Animal

American ginseng root stimulated copulatory behavior in male rats (Murphy et al., 1998); aqueous extract possessed significant gastricmodulating effect on brain neuronal activity in rats (Yuan et al., 1998a, 1998b); methanolic American ginseng extract exhibited liver-protective effect against D-galactosamine- and lipopolysaccharide-induced injury in mice (Yoshikawa et al., 1998); aqueous American ginseng extract significantly exhibited hypoglycemic activity in mice (Oshima et al., 1987); inhibitory effect on the cerebral cortex and moderately stimulates subcortical centers (Bensky et al., 1986); saponin extract decreased plasma glucose levels in resting rats (Martinez and Staba, 1984). Research on fractions and isolated constituents have been conducted, yielding results which may or may not be consistent with studies on whole American ginseng extracts: isolated saponins significantly elevated total and maximum heat production and improved cold tolerance in rats (Wang and Lee, 2000); pseudoginsenoside-F11 antagonized scopolamine-induced memory impairment in mice and rats (Li et al., 1999); ginsenoside Rb1 prevented scopolamine-induced amnesia in rats (Benishin et al., 1991).

In vitro

American ginseng root extract showed effective antioxidant activity in both lipid and aqueous mediums by chelation of metal ions and free radical scavenging (Kitts et al., 2000); ethanolic extract showed nicotinic activity by displacement of 3H-(-)nicotine from human brain cerebral cortex membranes (Lewis et al., 1999); inhibited thrombin-induced endothelin release in cultured human umbilical vein endothelial cells (Yuan et al., 1999); ethyl acetate American ginseng extract inhibited nitrite production by inducible nitric oxide synthase (iNOS) (Wang et al., 2000); isolated quinqueginsin inhibited human immunodeficiency virus-1 reverse transcriptase (Wang and Ng, 2000); standardized extract and breast chemotherapeutic drugs synergistically inhibited MCF-7 breast cancer cell growth (Duda et al., 1999); extract exhibited estrogenic activity in MCF-7 breast cancer cells (Duda et al., 1997).

Mechanism of Action

The mechanisms of action of American ginseng are not fully understood. Some suggested mechanisms include:

Animal

Reduced plasma prolactin levels and significantly stimulated copulatory behavior due to ginseng-induced alterations in dopaminergic neurotransmission (Murphy et al., 1998). Research also suggests that American ginseng’s apparent increase of the male sexual arousal response is the result of relaxing and vasodilating the corpus cavernosum, allowing greater erectile performance, which appears to occur by means of an interaction with nitric oxide synthase (Nocerino et al., 2000).

Regulated GABAergic neurotransmission (Yuan et al., 1998a; Yuan et al., 1998b).

In vitro

Facilitated the release of acetylcholine (ACh) from hippocampal slices (ginsenoside Rb1, isolated from American ginseng roots and fibers), which is associated with an increased uptake of choline into nerve endings. The ability of Rb1 to prevent memory deficit in animal experiments may be related to ACh metabolism in the central nervous system (Benishin et al., 1991).

Contraindications

None known.

Traditional Chinese Medicine (TCM) Contraindications

Cold-Damp Stomach (condition marked by intolerance of cold and abdominal distention) (Bensky et al., 1986).

Pregnancy and Lactation: No known restrictions (McGuffin et al., 1997).

Adverse Effects

None known.

Drug Interactions

None known. Insulin levels in diabetic patients may need monitoring due to American ginseng’s blood sugar modulating effect.

American Herbal Products Association (AHPA) Safety Rating

Class 1: Herbs that can be safely consumed when used appropriately (McGuffin et al., 1997).

Regulatory Status

Canada: Food, if no therapeutic claims are made, and New Drug if drug claims are made (HPB, 1993) except as per the Traditional Herbal Medicine (THM) Policy. Permitted as a THM, if the claim(s) are supported by traditional references, requiring premarket authorization and assignment of a Drug Identification Number (DIN) (Health Canada, 1999). Also, permitted as a homeopathic over-the-counter (OTC) drug with premarket authorization and assignment of a DIN (Health Canada, 2001).

China: Regulated as a drug, which must meet the State Standard of People’s Republic of China 1998: Grade and Quality Standards of American Ginseng. American ginseng dried roots and teas are Class 3 materials (herbal pharmaceuticals). American ginseng capsules are also Class 3 drugs, but require additional premarket licenses and inspection from the Ministry of Health (AAFC, 1998; Xiao, 2000).

France: No official monograph for this species of Panax.

Germany: No official monograph for this species of Panax.

Italy: No official monograph for this species of Panax.

Japan: Used in traditional Kampo medicine (Rister, 1999). Before May 23, 2000, American ginseng was considered a drug; now deregulated by Japan’s Ministry of Health and Welfare, and may be sold as a food product without medical efficacy claims (USDS, 2000).

Sweden: Possible Natural Remedy for self-medication requiring advance application for marketing authorization. As of January 2001, no American ginseng products have been listed in the Medical Products Agency (MPA) “Authorised Natural Remedies” (MPA, 2001). Food, if no therapeutic claims are made.

Switzerland: No official monograph for this species of Panax.

U.K.: Entered in General Sales List, Table A (internal or external use) of Schedule 1 (subject to a full product license) (GSL, 1994).

U.S.: Dietary supplement (USC, 1994). The homeopathic tincture (1X) of the fresh or dried root is an OTC Class C drug of the Homeopathic Pharmacopoeia of the United States (HPUS, 1992).

Clinical Review

Six studies are outlined in the following table, “Clinical Studies on American Ginseng,” including a total of 126 participants. All but one of the studies (Morris et al., 1996), demonstrated positive effects on diabetes, circulation, or oxygen utilization during athletic performance. One double-blind placebo-controlled (DB, PC) study and one PC crossover (CO) study reported beneficial effects of American ginseng root powder on postprandial glycemia in type 2 diabetes mellitus subjects (Vuksan et al., 2000a; 2000b). A subsequent randomized, PC, CO study evaluated the effects of powdered American ginseng on postprandial glycemia in healthy individuals (Vuksan et al., 2001). These subjects experienced a reduction in postprandial glycemia. Improved athletic performance was the focus of two PC studies (Goode et al., 1993; Morris, 1996). One small comparison, PC study examined the effects of ginseng on psychomotor skills and found Asian and American ginseng to have equal effects on improving proofreading error-detection and mood-fatigue (Johnson et al., 1980). All these studies are small and need confirmation in larger trials. The evidence on American ginseng’s ability to lower postprandial blood sugar levels in both healthy individuals and type 2 diabetics in one dose is mounting but needs validation in larger, longer-term studies.

Branded Products

Chai-Na-Ta^® CNT2000™ capsules: Chai-Na-Ta Corp., 5965 205A Street / Langley, BC / V3A 8C4 / Canada / Tel.: (800) 406-7668 / Fax (604) 533-8891 / www.chainata.com. One capsule, standardized to 6% genenosides, contains 500 mg of 3-year-old Ontario-grown, dried and ground American ginseng root, standardized to 6% ginsenosides.

References

AAFC. See: Agriculture and Agri-Food Canada.

Agriculture and Agri-Food Canada (AAFC). Ginseng and Nutraceuticals in China. Ottawa, ON: Agriculture and Agri-Food Canada; 1998, Sept.

Agriculture and Agri-Food Canada (AAFC). Special Crops: Canadian Ginseng Profile. Ottawa, ON: Agriculture and Agri-Food Canada; 2000; Available at: http://www.agr.ca/misb/spcrops/gin_e.html.

Awang D. The neglected ginsenosides of North American ginseng (Panax quinquefolius L.). J Herbs Spices & Med Plants 2000;7(2):103–9.

Awang D. The anti-stress potential of North American ginseng (Panax quinquefolius L.). J Herbs, Spices & Med Plants 1998;6(2):87–91.

Benishin C, Lee R, Wang L, Liu H. Effects of ginsenoside Rb1 on central cholinergic metabolism. Pharmacology 1991;42(4):223–9.

Bensky D, Gamble A, Kaptchuck T. Chinese Herbal Medicine Materia Medica. Seattle, WA: Eastland Press; 1986;518.

Chan T, But P, Cheng S, et al. Differentiation and authentication of Panax ginseng, Panax quinquefolius, and ginseng products by using HPLC/MS. Annl Chem 2000;72(6):1281–7.

Chen YJ, Wu CF, Awang DVC, et al. Ginsenosides: The Chemistry, Pharmacology, and Clinical Perspectives. 2003 [in press].

Chuang W, Wu H, Sheu S, et al. A comparative study on commercial samples of Ginseng Radix. Planta Med 1995;61:459–65.

Court W. Ginseng: The Genus Panax. Amsterdam: Harwood Academic Publishers; 2000.

Court W, Reynolds L, Hendel J. Influence of root age on the concentration of ginsenosides of American ginseng (Panax quinquefolium). Can J Plant Sci 1996;76:853–5.

Dou D, Hou W, Chen Y. Studies on the characteristic constituents of Chinese ginseng and American ginseng. Planta Med 1998;64:585–6.

Duda R, Zhong Y, Navas V, et al. American ginseng and breast cancer therapeutic agents synergistically inhibit MCF-7 breast cancer cell growth. J Surg Oncol 1999;72(4):230–9.

Duda R, Taback B, Navas V, Zhong Y, Slomovic B, Alvarez J. Comparison of estrogenicity of Panax quinquefolium and Panax ginseng in MCF-7 breast cancer cells (meeting abstract). Proc Annu Meet Am Assoc Cancer Res 1997;38:A756.

Felter H, Lloyd J. King’s American Dispensatory, 18th edition, 3rd revision. Cincinnati, OH: The Ohio Valley Co.; 1898;1429–30.

Foster S. American Ginseng Panax quinquefolius. Austin, TX: American Botanical Council; Botanical Series No. 308;1999.

Foster S, Chongxi Y. Herbal Emissaries: Bringing Chinese Herbs to the West. Rochester, VT: Healing Arts Press; 1992;102–12.

General Sale List (GSL). Statutory Instrument 1994 No. 2410 – The Medicines (Products Other Than Veterinary Drugs). Amendment Order 1994. London, U.K.: Her Majesty’s Stationery Office (HMSO). 1994.

Goode R, Chatha D, Baker J, et al. The Effects of Ginseng on Physical Performance in Human Subjects. Toronto, ON: University of Toronto Dept. of Physiology, Faculty of Medicine and School of Physical and Health Education; 1993.

GSL. See: General Sale List.

Health Canada. Listing of Drugs Currently Regulated as New Drugs—Revised April 1999. Ottawa, ON: Health Canada; 1999, April;11, 21–2.

Health Canada. Product Information: Aralia quinquefolia. In: Drug Product Database (DPD). Ottawa, ON: Health Canada Therapeutic Products Programme; 2001.

Health Protection Branch (HPB). Ginseng. In: HPB Status Manual. Ottawa, ON: Health Protection Branch; 1993, Feb. 19;89.

Heffern R. The Use of North American Ginseng. In: The Complete Book of Ginseng. Millbrae, CA: Celestial Arts; 1976;81–9.

Homeopathic Pharmacopoeia of the United States (HPUS) Revision Service Official Compendium from July 1, 1992. Washington, DC: Homeopathic Pharmacopoeia Convention of the United States; 1992;0201—ARQU.

Hou J. The chemical constituents of ginseng plants. Comparative Med East and West 1977;5(2):123–45.

HPB. See: Health Protection Branch.

HPUS. See: Homeopathic Pharmacopoeia of the United States.

Johnson A, Jiang N, Stuba E. Whole ginseng effects on human response to demands for performance. Proceedings of the 3rd International Ginseng Symposium, Sept. 8–10;1980. Seoul Korea: Korea Ginseng Research Institute.

Kitts D, Wijewickreme A, Hu C. Antioxidant properties of a North American ginseng extract. Mol Cell Biochem 2000;203(1–2):1–10.

Lewis R, Wake G, Court G, et al. Non-ginsenoside nicotinic activity in ginseng species. Phytother Res 1999;13(1):59–64.

Li T, Mazza G, Cottrell A, Gao L. Ginsenosides in roots and leaves of American ginseng. J Agric Food Chem 1996;44:717–20.

Li Z, Guo Y, Wu C, Li X, Wang J. Protective effects of pseudoginsenoside-F11 on scopolamine-induced memory impairment in mice and rats. J Pharm Pharmacol 1999;51(4):435–40.

Martinez B, Staba E. The physiological effects of Aralia, Panax and Eleutherococcus on exercised rats. Jpn J Pharmacol 1984;35(2):79-85.

McGuffin M, Hobbs C, Upton R, Goldberg A (eds.). American Herbal Products Association’s Botanical Safety Handbook. Boca Raton, FL: CRC Press; 1997;82.

Medical Products Agency (MPA). Naturläkemedel: Authorised Natural Remedies (as of January 24, 2001). Uppsala, Sweden: Medical Products Agency. 2001.

Millspaugh C. Medicinal Plants. Philadelphia, PA: John C. Yorston & Co.; 1892;276–9.

Moerman D. Native American Ethnobotany. Portland, OR: Timber Press; 1998;376–7.

Morris A, Jacobs I, McLellan T, et al. No ergogenic effect of ginseng ingestion. Int J Sport Nutr 1996;(6):263–71.

MPA. See: Medical Products Agency.

Murphy L, Cadena R, Chavez D, Ferraro J. Effect of American ginseng (Panax quinquefolium) on male copulatory behavior in the rat. Physiol Behav 1998;64(4):445–50.

Nocerino E, Amato M, Izzo A. The aphrodisiac and adaptogenic properties of ginseng. Fitoterapia 2000, Aug;71(0):S1–S5.

Oshima Y, Sato K, Hikino H. Isolation and hypoglycemic activity of quinquefolans A, B, and C, glycans of Panax quinquefolium roots. J Nat Prod 1987;50(2):188–90.

Pharmacopoeia of the People’s Republic of China (PPRC 2000 English Edition). Beijing, China; Chemical Industry Press. 2000;183–84.

PPRC. See: Pharmacopoeia of the People’s Republic of China.

Rafinesque C. Medical Flora: Manual of the Medical Botany of the United States of America, Volume II. Philadelphia, PA: Samuel C. Atkinson; 1830;53.

Ren G, Chen F. Simultaneous quantification of ginsenosides in American ginseng (Panax quinquefolium) root powder by visible/near-infrared reflectance spectroscopy. J Agric Food Chem 1999;47(7):2771–5.

Reynolds L. Effects of drying on chemical and physical characteristics of American ginseng (Panax quinquefolius L.). J Herbs, Spices & Med Plants 1998;6(2):9–21.

Rister RS. American Ginseng. In: Japanese Herbal Medicine: The Healing Art of Kampo. Garden City Park, NY: Avery Publishing Group; 1999;23–4.

Robbins C. Panax quinquefolius popularity prompts probe. Medicinal Plant Conservation 1997, Nov.1;4:13–5.

Scudder J. The American Eclectic Materia Medica and Therapeutics. Cincinnati, OH: John M. Scudder; 1891;454.

Shaw P, But P. Authentication of Panax species and their adulterants by random-primed polymerase chain reaction. Planta Med 1995;61:466–9.

Sontaniemi E, Haapakoski E, Rautio A. Ginseng therapy in non-insulin-dependent diabetic patients. Diabetes Care 1995;18:1373–5.

State Standard of People’s Republic of China. Grade and Quality Standards of Products of Processed American Ginseng. Beijing, China: Standards Press of China; 1998;GB/T 17356.1~17356.5.

United States Congress (USC). Public Law 103–417: Dietary Supplement Health and Education Act of 1994. Washington, DC: 103rd Congress of the United States; 1994.

United States Department of Agriculture (USDA). Farmers Bulletin Number 2201: Growing Ginseng. Washington, DC: United States Department of Agriculture; 1978, June.

United States Department of Commerce (USDOC). Ginseng: United States Exports by Type and Unit Value. Washington, DC: U.S. Department of Commerce. 1995, April;83–85.

United States Department of Commerce (USDOC). Ginseng Roots, Fresh or Dried, Whether or not Cut, Crushed or Powdered. U.S. Domestic Exports: November 2000 and 2000 YTD, not Seasonally Adjusted; December 1999 and 1999 YTD, not Seasonally Adjusted. Washington, DC: U.S. Department of Commerce; 2000.

United States Department of State (USDS). Deregulation of Herbs Used as Dietary Supplements. Country: Japan. Washington, DC: U.S. & Foreign Commercial Service and U.S. Department of State; June 12, 2000; Available at: http://www.csjapan.doc.gov/imi0006/herb.html.

United States Fish and Wildlife Service (USFWS). News Release: Status Review of American Ginseng Plant. Washington, DC: Department of the Interior: U.S. Fish and Wildlife Service; 1977, Aug. 11;INT:4735–77.

United States Fish and Wildlife Service (USFWS). U.S. Fish and Wildlife Service Announces First-Ever Export Restrictions for Ginseng Roots. Washington DC: U.S. Fish and Wildlife Service International Affairs; 1999a. Available at: http://international.fws.gov/global/ginsenpr.html.

United States Fish and Wildlife Service (USFWS). How to Determine the Age of Ginseng Plants. Washington DC: U.S. Fish and Wildlife Service International Affairs; 1999b. Available at: http://international.fws.gov/global/ginseng.html.

United States Fish and Wildlife Service (USFWS). Convention Permit Applications for Ginseng. Washington DC: U.S. Fish and Wildlife Service International Affairs; 1999c. Available at: http://international.fws.gov/animals/gingfind.html.

USC. See: United States Congress.

USDA. See: United States Department of Agriculture.

USDOC. See: United States Department of Commerce.

USDS. See: United States Department of State.

USFWS. See: United States Fish and Wildlife Service.

Vuksan V, Sievenpiper J, Wong J, et al. American ginseng (Panax quinquefolius L.) attenuates postprandial glycemia in a time-dependent but not dose-dependent manner in healthy individuals. Am J Clin Nutr 2001;73:753–8.

Vuksan V, Sievenpiper, J, Koo, V, et al. American ginseng (Panax quinquefolius L.) reduces postprandial glycemia in nondiabetic subjects and subjects with type 2 diabetes mellitus. Arch Intern Med 2000a;160:1009–13.

Vuksan V, Stavro MP, Sievenpiper JL, et al. Similar postprandial glycemic reductions with escalation of dose and administration time of American ginseng in type 2 diabetes. Diabetes Care 2000b;23(9):1221–6.

Wang C, Lee T. Effect of ginseng saponins on cold tolerance in young and elderly rats. Planta Med 2000;66:144–7.

Wang C, Shiao Y, Kuo Y, et al. Inducible nitric oxide synthase inhibitors from Saposhnikovia divaricata and Panax quinquefolium. Planta Med 2000;66:644–7.

Wang H, Ng T. Quinqueginsin, a novel protein with anti-human immunodeficiency virus, antifungal, ribonuclease and cell-free translation-inhibitory activities from American ginseng roots. Biochem Biophys Res Commun 2000;269(1):203–8.

Wang W, Chen H, Hsu T, Wang Y. Alteration of pulse in human subjects by three Chinese herbs. Am J Chin Med 1994;22(2):197–203.

Wenkui L., Chungang G., Hongjie Z. et al. Use of High-Performance Liquid Chromatography—Tandem Mass Spectrometry to Distinguish Panax ginseng C.A. Meyer (Asian Ginseng) and Panax quinquefolius L. (North American Ginseng). Anal Chem 2000;72:5417—5422.

Wood G, Bache F. Panax, U.S. In: The Dispensatory of the United States of America, 11th edition. Philadelphia, PA: J.B. Lippincott and Co; 1858;575–6.

Wood H, LaWall C, Youngken H, et al. The Dispensatory of the United States of America, 21st edition. Philadelphia, PA: J.B. Lippincott Co.; 1926;1316.

Xiao M. The Canadian Ginseng Industry: Preparing for the 21st Century. Ottawa, ON: Agriculture and Agri-Food Canada; 2000–02–07.

Xiao-fan Z, Liscum G. Chinese Medicinal Teas. Boulder, CO: Blue Poppy Press, Inc.; 1996;269–70.

Yen K. The Illustrated Chinese Materia Medica—Crude and Prepared. Taipei, Taiwan: SMC Publishing Inc.; 1992;53.

Yoshikawa M, Murakami T, Yashiro K, et al. Bioactive saponins and glycoside. XI. Structures of new dammarane-type triterpene oligoglycosides, quinquenosides I, II, III, IV, and V, from American ginseng, the roots of Panax quinquefolium L. Chem Pharm Bull (Tokyo); 1998;46(4):647–54.

Yuan C, Attele A, Wu J, Liu D. Modulation of American ginseng on brainstem GABAergic effects in rats. J Ethnopharm 1998a;62(3):215–22.

Yuan C, Attele A, Wu J, et al. Panax quinquefolium L. inhibits thrombin-induced endothelin release in vitro. Am J Chin Med 1999;27(2–3):331–8.

Yuan C, Wu J, Lowell T, Gu M. Gut and brain effects of American ginseng root on brainstem neuronal activities in rats. Am J Chin Med 1998b;26(1):47–55.

Zheng Y, Zhang C, Li X, Guo S. A comparison between Chinese Panax quinquefolius and imported Panax quinquefolius—analysis of composition of essential oil in Panax quinquefolius. [in Chinese]. Yao Hsueh Hsueh Pao 1989;24(2):118–21.