THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINEVolume 7 Number 5 2001 pp 405ndash515Mary Ann Liebert Inc

Therapeutic Plants of Ayurveda A Review of SelectedClinical and Other Studies for 166 Species

SARAH KHAN MS MPH CNS and MICHAEL J BALICK PhD

ABSTRACT

This paper reports on the results of a literature survey involving 166 different species of plantsused in the Ayurvedic pharmacopoeia based on a sampling of the literature available to us Wefound a wide range of clinical and other in vivo studies for many of the plant-based therapiesutilized in the Ayurvedic system Of the 166 plants investigated 72 (43) had at least one ormore human studies and 103 (62) had one or more animal studies These results appear to con-tradict the generally held notion that herbal remedies used in non-Western systems of botani-cal medicine have not been evaluated in human or in vivo trials Some of these studies are notalways as large or methodologically rigorous as clinical studies reported in major medical jour-nals Indeed a critical assessment of the research according to the standards of evidence-basedmedicine would eliminate many of these studies for lack of rigor according to criteria of ran-domization sample size adequacy of controls etc However the studies do suggest whichspecies might be appropriate for larger and better-controlled trials in the future Accordingly asynopsis of the plants their therapeutic applications and their clinical or experimental evalua-tions is presented

405

INTRODUCTION

Non-Western healing systems that utilizebotanical medicines are often criticized be-

cause of a supposed paucity of in vivo studies tosupport the safety and efficacy of individualplants or plant mixtures For example Barrett etal (1999) state that therapies outside the med-ical mainstream suffer from a dearth of researchand critical evaluation From a biomedical par-adigm rigorous studies include those that pro-vide randomized controlled data on efficacy aswell as information on toxicity dosage method

of use and adverse reactions Few herbals orother references available to practitioners ofbotanical medicine contain information aboutor citations of clinical trials or related studiesAt the same time billions of people around theworld have studied and utilized ancient med-ical systems such as Ayurveda (translated as theldquoscience of liferdquo) for centuries

To evaluate the availability of studies onplants used in Ayurveda we conducted asearch in two databases as well as other sourcesof information using a list of 166 species thatare important to this system of medicine

Institute of Economic Botany The New York Botanical Garden Bronx NY

ORIGINAL PAPERS

KHAN AND BALICK406

MATERIALS AND METHODS

The research was conducted between Janu-ary 1996 and January 2000 The databasessearched were MEDLINEreg and NAPRALERTIn addition we collected literature on tradi-tional medicine and searched two Indian jour-nals not included in MEDLINE Aryavaidyanand the Indian Journal of Medical Research Thesepublications were selected based on theiravailability to us as examples of Indian jour-nals that report on studies of plants and theirtreatment of disease There are many other In-dian journals that contain a great deal of valu-able information however they were not ac-cessible to usmdashwe expect that if access to thistype of traditional knowledge can be facilitatedin some way much more information of inter-est could be located In this paper we only con-sider those studies that include individualplants or mixtures of plants consistent with thephilosophy of Ayurveda We did not includesix species that have been reported on in manyjournals in both human and animal studies Al-lium sativum L Cannabis indica Lam Digitalispurpurea L Papaver somniferum L Rauwolfiaserpentina L and Zingiber officinalis RoscoeHowever we did include these species in thecalculation of percentage of animal and humantrials of the 166 Ayurvedic medicinal plants

RESULTS AND DISCUSSION

Summary of human studies

A summary of the human studies and thespecies included in the plant mixtures are pre-sented in Table 1 Ayurvedic Plants and Hu-man Studies The disease categories listed inTable 1 are graphically depicted in Figure 1 asbreakdown into eleven disease categories forthe 166 plants (minus the six species alreadydocumented) with human studies The diseasecategories include antimicrobial antimuta-gens cardiovascular dermatology Diabetesmellitus gastrointestinal liver dysfunction nervous system paininflammation renalbloodimmune system and other There are atotal of 145 effects based on the 66 human stud-ies In a few instances when one plant demon-

strated more than one effect ie reduction ofboth blood glucose and triglyceride levels theeffect was counted in both the cardiovascularand Diabetes mellitus categories For the sake ofcomparison Figure 2 represents a breakdownof drugs used in the US pharmacopoeia ac-cording to treatment category based on thework of Paul Cox (1994)

Table 2 is a detailed list of all the plants or-ganized by genus and species with the familynames Information on common Sanskrit andEnglish names is also presented as well asmention of the plant part used preparation anddosage used in the study design model andsample size when known results (negative andpositive) and the original reference that wasexamined Forty-three percent (43) (a total of72) of the species in Table 2 contain referenceto one or more studies with humans and 62(a total of 103) of the species listed in this tablecontain reference to at least one animal trialCareful examination of the studies revealed avariation in sample size quality of researchand presentation of results However there isa great deal of interesting information con-tained in these studies representing a signifi-cant accumulation of evidence supporting theefficacy of plant therapies used in AyurvedaAlthough the table is quite long and detailedthere are a number of plants exhibiting im-pressive therapeutic effects in humans At thesame time this corpus of information serves topoint the way to species that deserve furtherstudy both in animal models and at the clinicToward this end we suggest the adoption ofldquoGood Botanical Practicesrdquo (Balick 1999) withproperly collected vouchered materials usedto produce the phytotherapies under studyThis is the only way that reproducibility of re-sults can be assured should further testing bewarranted

CONCLUSIONS

Plants have long been the principal tools oftraditional medical systems Although ancientin origins many traditional medical paradigmsand their pharmacopoeias have evolved intoquite sophisticated healing systems usingthousands of plants and other natural materi-

THERAPEUTIC PLANTS OF AYURVEDA 407

als such as minerals and animal products Inmany parts of the world traditional medicineis still used to provide the major part of pri-mary health care The World Health Organiza-tion has estimated that the majority of theworldrsquos population depends on botanical med-icines for basic health care needs (Akerele1985) Reasons for this include the fact thatthese local systems are culturally acceptablecheaper for many conditions as compared tobiomedicine and efficacious in many of the cir-cumstances in which they are used

In a recent editorial in the New England Jour-nal of Medicine the editors cautioned against the

use of herbal medicines as ldquoa reversion to irra-tional approaches to medical practicerdquo (Angelland Kassirer 1998) In this paper we have at-tempted to dispel the all-too-commonly heldnotion that no clinical or other evidence existsto support the use of plants used in traditionalmedical systems We acknowledge that someof the studies are not as rigorous as desired be-cause of resource or other limitations How-ever the work described in this review canserve to help guide future studies by pointingout promising therapies and thus research av-enues for specific conditions In the case ofAyurvedic medicine Indian journals often re-

FIG 1 Ayurvedic medicinal plant uses classified according to the treatment categories (Based on human studiesn 5 66)

FIG 2 US Pharmacopoeia drug uses classified according to the treatment categories From Cox 1994

gional or those published by individual re-search centers are rich in experimental studiesas well This exercise has also pointed out theneed for access to such publications via greaterinternational cooperation involving informa-tion exchange

This study has been limited by our own ac-cess to information and there are numerous ad-ditional journals that contain information onplants and complex mixtures of plants pre-pared according to traditional formulationsused in the Ayurvedic medical system Wehave undertaken this task in the hope that someof the initial studies presented may help to di-rect research on plants deserving of more in-tensive evaluation as clinical therapies

ACKNOWLEDGMENTS

We are grateful to Scott Gerson MD PhDmedical director of the National Institute ofAyurvedic Medicine Brewster NY for pro-viding us with a listing of the species ofAyurvedic medicinal plants discussed in thispaper We would like to thank the followingthe NAPRALERT staff for providing informa-tion on clinical trials The New York BotanicalGarden Library (for interlibrary loans) JenniferCooper of Naturersquos Herbs for providing refer-ences on some of the plants The Asian Eco-nomic Botany Fund of The New York BotanicalGarden (for funding travel and SK salary) andThe New York Botanical Garden Institute of

Economic Botany Bronx NY staff and internsJan Stevenson Kate Armstrong (1998 EverettPublic Service Intern) Kelvin Chan (volunteer)with special thanks to Rebekka Stone (ResearchAssistant) and Roberta Lee MD We wouldalso like to express our gratitude to GerryBodeker EdD for his thoughtful commentson the piece and to Jackie Wootton MEd andKim Jobst MA DM MRCP MFHom

We are also grateful to The Philecology Trustand The Metropolitan Life Foundation for theirgenerous support of Michael Balickrsquos researchprogram in ethnomedicine

REFERENCES

Angell M Kassirer JP Alternative medicine The risks ofuntested and unregulated remedies [editorial] N Eng-land J Med 1998339839ndash841

Akerele O The WHO Traditional Medicine ProgrammePolicy and Implementation International TraditionalHealth Newsletter Geneva Switzerland World HealthOrganizations 198511

Balick MJ Good Botanical Practices In Eskinazi D (ed)Botanical Medicine Efficacy Quality Assurance andRegulation Larchmont NY Mary Ann Liebert Inc1999121ndash125

Barrett B Kiefer D Rabago D Assessing the risks andbenefits of herbal medicine An overview of scientificevidence Altern Ther Health Med 19995(4)40ndash49

Cox P The ethnobotanical approach to drug discoveryStrengths and limitations In Chadwick D Marsh J(eds) Ethnobotany and the Search for New Drugs JohnWiley amp Sons 199425ndash36

Address reprint requests toMichael J Balick PhD

The New York Botanical GardenBronx NY 10458

E-mail mbalicknybgorg

KHAN AND BALICK408

The Foundation for the Revitilization of Local HealthTraditions (wwwfrlht-indiaorg) founded by DarshanShankar in 1991 is one such pioneering organization ded-icated to the conservation of Indian biodiversity and lo-cal health traditions and cultures

KHAN AND BALICK406

MATERIALS AND METHODS

The research was conducted between Janu-ary 1996 and January 2000 The databasessearched were MEDLINEreg and NAPRALERTIn addition we collected literature on tradi-tional medicine and searched two Indian jour-nals not included in MEDLINE Aryavaidyanand the Indian Journal of Medical Research Thesepublications were selected based on theiravailability to us as examples of Indian jour-nals that report on studies of plants and theirtreatment of disease There are many other In-dian journals that contain a great deal of valu-able information however they were not ac-cessible to usmdashwe expect that if access to thistype of traditional knowledge can be facilitatedin some way much more information of inter-est could be located In this paper we only con-sider those studies that include individualplants or mixtures of plants consistent with thephilosophy of Ayurveda We did not includesix species that have been reported on in manyjournals in both human and animal studies Al-lium sativum L Cannabis indica Lam Digitalispurpurea L Papaver somniferum L Rauwolfiaserpentina L and Zingiber officinalis RoscoeHowever we did include these species in thecalculation of percentage of animal and humantrials of the 166 Ayurvedic medicinal plants

RESULTS AND DISCUSSION

Summary of human studies

A summary of the human studies and thespecies included in the plant mixtures are pre-sented in Table 1 Ayurvedic Plants and Hu-man Studies The disease categories listed inTable 1 are graphically depicted in Figure 1 asbreakdown into eleven disease categories forthe 166 plants (minus the six species alreadydocumented) with human studies The diseasecategories include antimicrobial antimuta-gens cardiovascular dermatology Diabetesmellitus gastrointestinal liver dysfunction nervous system paininflammation renalbloodimmune system and other There are atotal of 145 effects based on the 66 human stud-ies In a few instances when one plant demon-

strated more than one effect ie reduction ofboth blood glucose and triglyceride levels theeffect was counted in both the cardiovascularand Diabetes mellitus categories For the sake ofcomparison Figure 2 represents a breakdownof drugs used in the US pharmacopoeia ac-cording to treatment category based on thework of Paul Cox (1994)

Table 2 is a detailed list of all the plants or-ganized by genus and species with the familynames Information on common Sanskrit andEnglish names is also presented as well asmention of the plant part used preparation anddosage used in the study design model andsample size when known results (negative andpositive) and the original reference that wasexamined Forty-three percent (43) (a total of72) of the species in Table 2 contain referenceto one or more studies with humans and 62(a total of 103) of the species listed in this tablecontain reference to at least one animal trialCareful examination of the studies revealed avariation in sample size quality of researchand presentation of results However there isa great deal of interesting information con-tained in these studies representing a signifi-cant accumulation of evidence supporting theefficacy of plant therapies used in AyurvedaAlthough the table is quite long and detailedthere are a number of plants exhibiting im-pressive therapeutic effects in humans At thesame time this corpus of information serves topoint the way to species that deserve furtherstudy both in animal models and at the clinicToward this end we suggest the adoption ofldquoGood Botanical Practicesrdquo (Balick 1999) withproperly collected vouchered materials usedto produce the phytotherapies under studyThis is the only way that reproducibility of re-sults can be assured should further testing bewarranted

CONCLUSIONS

Plants have long been the principal tools oftraditional medical systems Although ancientin origins many traditional medical paradigmsand their pharmacopoeias have evolved intoquite sophisticated healing systems usingthousands of plants and other natural materi-

THERAPEUTIC PLANTS OF AYURVEDA 407

als such as minerals and animal products Inmany parts of the world traditional medicineis still used to provide the major part of pri-mary health care The World Health Organiza-tion has estimated that the majority of theworldrsquos population depends on botanical med-icines for basic health care needs (Akerele1985) Reasons for this include the fact thatthese local systems are culturally acceptablecheaper for many conditions as compared tobiomedicine and efficacious in many of the cir-cumstances in which they are used

In a recent editorial in the New England Jour-nal of Medicine the editors cautioned against the

use of herbal medicines as ldquoa reversion to irra-tional approaches to medical practicerdquo (Angelland Kassirer 1998) In this paper we have at-tempted to dispel the all-too-commonly heldnotion that no clinical or other evidence existsto support the use of plants used in traditionalmedical systems We acknowledge that someof the studies are not as rigorous as desired be-cause of resource or other limitations How-ever the work described in this review canserve to help guide future studies by pointingout promising therapies and thus research av-enues for specific conditions In the case ofAyurvedic medicine Indian journals often re-

FIG 1 Ayurvedic medicinal plant uses classified according to the treatment categories (Based on human studiesn 5 66)

FIG 2 US Pharmacopoeia drug uses classified according to the treatment categories From Cox 1994

gional or those published by individual re-search centers are rich in experimental studiesas well This exercise has also pointed out theneed for access to such publications via greaterinternational cooperation involving informa-tion exchange

This study has been limited by our own ac-cess to information and there are numerous ad-ditional journals that contain information onplants and complex mixtures of plants pre-pared according to traditional formulationsused in the Ayurvedic medical system Wehave undertaken this task in the hope that someof the initial studies presented may help to di-rect research on plants deserving of more in-tensive evaluation as clinical therapies

ACKNOWLEDGMENTS

We are grateful to Scott Gerson MD PhDmedical director of the National Institute ofAyurvedic Medicine Brewster NY for pro-viding us with a listing of the species ofAyurvedic medicinal plants discussed in thispaper We would like to thank the followingthe NAPRALERT staff for providing informa-tion on clinical trials The New York BotanicalGarden Library (for interlibrary loans) JenniferCooper of Naturersquos Herbs for providing refer-ences on some of the plants The Asian Eco-nomic Botany Fund of The New York BotanicalGarden (for funding travel and SK salary) andThe New York Botanical Garden Institute of

Economic Botany Bronx NY staff and internsJan Stevenson Kate Armstrong (1998 EverettPublic Service Intern) Kelvin Chan (volunteer)with special thanks to Rebekka Stone (ResearchAssistant) and Roberta Lee MD We wouldalso like to express our gratitude to GerryBodeker EdD for his thoughtful commentson the piece and to Jackie Wootton MEd andKim Jobst MA DM MRCP MFHom

We are also grateful to The Philecology Trustand The Metropolitan Life Foundation for theirgenerous support of Michael Balickrsquos researchprogram in ethnomedicine

REFERENCES

Angell M Kassirer JP Alternative medicine The risks ofuntested and unregulated remedies [editorial] N Eng-land J Med 1998339839ndash841

Akerele O The WHO Traditional Medicine ProgrammePolicy and Implementation International TraditionalHealth Newsletter Geneva Switzerland World HealthOrganizations 198511

Balick MJ Good Botanical Practices In Eskinazi D (ed)Botanical Medicine Efficacy Quality Assurance andRegulation Larchmont NY Mary Ann Liebert Inc1999121ndash125

Barrett B Kiefer D Rabago D Assessing the risks andbenefits of herbal medicine An overview of scientificevidence Altern Ther Health Med 19995(4)40ndash49

Cox P The ethnobotanical approach to drug discoveryStrengths and limitations In Chadwick D Marsh J(eds) Ethnobotany and the Search for New Drugs JohnWiley amp Sons 199425ndash36

Address reprint requests toMichael J Balick PhD

The New York Botanical GardenBronx NY 10458

E-mail mbalicknybgorg

KHAN AND BALICK408

The Foundation for the Revitilization of Local HealthTraditions (wwwfrlht-indiaorg) founded by DarshanShankar in 1991 is one such pioneering organization ded-icated to the conservation of Indian biodiversity and lo-cal health traditions and cultures

THERAPEUTIC PLANTS OF AYURVEDA 407

als such as minerals and animal products Inmany parts of the world traditional medicineis still used to provide the major part of pri-mary health care The World Health Organiza-tion has estimated that the majority of theworldrsquos population depends on botanical med-icines for basic health care needs (Akerele1985) Reasons for this include the fact thatthese local systems are culturally acceptablecheaper for many conditions as compared tobiomedicine and efficacious in many of the cir-cumstances in which they are used

In a recent editorial in the New England Jour-nal of Medicine the editors cautioned against the

use of herbal medicines as ldquoa reversion to irra-tional approaches to medical practicerdquo (Angelland Kassirer 1998) In this paper we have at-tempted to dispel the all-too-commonly heldnotion that no clinical or other evidence existsto support the use of plants used in traditionalmedical systems We acknowledge that someof the studies are not as rigorous as desired be-cause of resource or other limitations How-ever the work described in this review canserve to help guide future studies by pointingout promising therapies and thus research av-enues for specific conditions In the case ofAyurvedic medicine Indian journals often re-

FIG 1 Ayurvedic medicinal plant uses classified according to the treatment categories (Based on human studiesn 5 66)

FIG 2 US Pharmacopoeia drug uses classified according to the treatment categories From Cox 1994

gional or those published by individual re-search centers are rich in experimental studiesas well This exercise has also pointed out theneed for access to such publications via greaterinternational cooperation involving informa-tion exchange

This study has been limited by our own ac-cess to information and there are numerous ad-ditional journals that contain information onplants and complex mixtures of plants pre-pared according to traditional formulationsused in the Ayurvedic medical system Wehave undertaken this task in the hope that someof the initial studies presented may help to di-rect research on plants deserving of more in-tensive evaluation as clinical therapies

ACKNOWLEDGMENTS

We are grateful to Scott Gerson MD PhDmedical director of the National Institute ofAyurvedic Medicine Brewster NY for pro-viding us with a listing of the species ofAyurvedic medicinal plants discussed in thispaper We would like to thank the followingthe NAPRALERT staff for providing informa-tion on clinical trials The New York BotanicalGarden Library (for interlibrary loans) JenniferCooper of Naturersquos Herbs for providing refer-ences on some of the plants The Asian Eco-nomic Botany Fund of The New York BotanicalGarden (for funding travel and SK salary) andThe New York Botanical Garden Institute of

Economic Botany Bronx NY staff and internsJan Stevenson Kate Armstrong (1998 EverettPublic Service Intern) Kelvin Chan (volunteer)with special thanks to Rebekka Stone (ResearchAssistant) and Roberta Lee MD We wouldalso like to express our gratitude to GerryBodeker EdD for his thoughtful commentson the piece and to Jackie Wootton MEd andKim Jobst MA DM MRCP MFHom

We are also grateful to The Philecology Trustand The Metropolitan Life Foundation for theirgenerous support of Michael Balickrsquos researchprogram in ethnomedicine

REFERENCES

Angell M Kassirer JP Alternative medicine The risks ofuntested and unregulated remedies [editorial] N Eng-land J Med 1998339839ndash841

Akerele O The WHO Traditional Medicine ProgrammePolicy and Implementation International TraditionalHealth Newsletter Geneva Switzerland World HealthOrganizations 198511

Balick MJ Good Botanical Practices In Eskinazi D (ed)Botanical Medicine Efficacy Quality Assurance andRegulation Larchmont NY Mary Ann Liebert Inc1999121ndash125

Barrett B Kiefer D Rabago D Assessing the risks andbenefits of herbal medicine An overview of scientificevidence Altern Ther Health Med 19995(4)40ndash49

Cox P The ethnobotanical approach to drug discoveryStrengths and limitations In Chadwick D Marsh J(eds) Ethnobotany and the Search for New Drugs JohnWiley amp Sons 199425ndash36

Address reprint requests toMichael J Balick PhD

The New York Botanical GardenBronx NY 10458

E-mail mbalicknybgorg

KHAN AND BALICK408

The Foundation for the Revitilization of Local HealthTraditions (wwwfrlht-indiaorg) founded by DarshanShankar in 1991 is one such pioneering organization ded-icated to the conservation of Indian biodiversity and lo-cal health traditions and cultures

gional or those published by individual re-search centers are rich in experimental studiesas well This exercise has also pointed out theneed for access to such publications via greaterinternational cooperation involving informa-tion exchange

This study has been limited by our own ac-cess to information and there are numerous ad-ditional journals that contain information onplants and complex mixtures of plants pre-pared according to traditional formulationsused in the Ayurvedic medical system Wehave undertaken this task in the hope that someof the initial studies presented may help to di-rect research on plants deserving of more in-tensive evaluation as clinical therapies

ACKNOWLEDGMENTS

We are grateful to Scott Gerson MD PhDmedical director of the National Institute ofAyurvedic Medicine Brewster NY for pro-viding us with a listing of the species ofAyurvedic medicinal plants discussed in thispaper We would like to thank the followingthe NAPRALERT staff for providing informa-tion on clinical trials The New York BotanicalGarden Library (for interlibrary loans) JenniferCooper of Naturersquos Herbs for providing refer-ences on some of the plants The Asian Eco-nomic Botany Fund of The New York BotanicalGarden (for funding travel and SK salary) andThe New York Botanical Garden Institute of

Economic Botany Bronx NY staff and internsJan Stevenson Kate Armstrong (1998 EverettPublic Service Intern) Kelvin Chan (volunteer)with special thanks to Rebekka Stone (ResearchAssistant) and Roberta Lee MD We wouldalso like to express our gratitude to GerryBodeker EdD for his thoughtful commentson the piece and to Jackie Wootton MEd andKim Jobst MA DM MRCP MFHom

We are also grateful to The Philecology Trustand The Metropolitan Life Foundation for theirgenerous support of Michael Balickrsquos researchprogram in ethnomedicine

REFERENCES

Angell M Kassirer JP Alternative medicine The risks ofuntested and unregulated remedies [editorial] N Eng-land J Med 1998339839ndash841

Akerele O The WHO Traditional Medicine ProgrammePolicy and Implementation International TraditionalHealth Newsletter Geneva Switzerland World HealthOrganizations 198511

Balick MJ Good Botanical Practices In Eskinazi D (ed)Botanical Medicine Efficacy Quality Assurance andRegulation Larchmont NY Mary Ann Liebert Inc1999121ndash125

Barrett B Kiefer D Rabago D Assessing the risks andbenefits of herbal medicine An overview of scientificevidence Altern Ther Health Med 19995(4)40ndash49

Cox P The ethnobotanical approach to drug discoveryStrengths and limitations In Chadwick D Marsh J(eds) Ethnobotany and the Search for New Drugs JohnWiley amp Sons 199425ndash36

Address reprint requests toMichael J Balick PhD

The New York Botanical GardenBronx NY 10458

E-mail mbalicknybgorg

KHAN AND BALICK408

The Foundation for the Revitilization of Local HealthTraditions (wwwfrlht-indiaorg) founded by DarshanShankar in 1991 is one such pioneering organization ded-icated to the conservation of Indian biodiversity and lo-cal health traditions and cultures