Essiac: Systematic review by the natural standard research collaboration

Abstract

The objective of this study was to evaluate the scientific evidence on the safety and efficacy of Essiac. This review serves as a clinical support tool. Electronic searches were conducted in 10 databases, 20 additional journals (not indexed in common databases), and bibliographies from 50 selected secondary references. No restrictions were placed on the language or quality of the publications. Standardized inclusion and exclusion criteria were used for selection. A review of the literature on Essiac and essiac formulations showed a lack of high-quality clinical trials to substantiate any of Essiac's traditional uses. Weak evidence from preclinical, animal, and laboratory data warranted a discussion regarding Essiac's use for cancer, but the results are inconclusive. Several other essiac preparations are noted in the literature, adding confusion to the exact formula and its proposed benefits. In general, there is a lack of both safety and efficacy data for Essiac and essiac formulations. Well-designed trials testing Essiac or individual herbal components are necessary to make firm recommendations.

Full text

REVIEW
Essiac: Systematic Review by the Natural Standard Research
Collaboration
Catherine
Ulbricht,
PharmD, Wendy
Weissner,
BA, SadafHashmi, MD, MPH,
Tracée Rae
Abrams,
PharmD,
Cynthia
Dacey,
PharmD,
Nicole
Giese,
MS,
Paul
Hammerness,
MD, Dana A. Hackman,
BS,
fenny
Kim,
PharmD,
Audrey
Nealon,
PharmD, Ruslan
Voloshin,
PharmD
The objective of this study was to evaluate the scientific evidence on the safety and efficacy of Essiac. This review serves as a ciinicai
support
tool.
Electronic searches were conducted in 10 databases, 20 additional journals (not indexed in common databases), and
bibliographies from 50 selected secondary references. No restrictions were placed on the language or quality of the publications. Stan-
dardized inclusion and exclusion criteria were used for selection. A review of the literature on Essiac and essiac formulations showed
a lack of high-quality clinical trials to substantiate any of Essiac's traditional uses. Weak evidence from preclinical, animal, and labora-
tory data warranted a discussion regarding Essiac's use for cancer, but the results are inconclusive. Several other essiac preparations
are noted in the literature, adding confusion to the exact formula and its proposed benefits. In general, there is a lack of both safety
and efficacy data for Essiac and essiac formulations. Well-designed trials testing Essiac or individual herbal components are necessary
to make firm recohimendations.
V."'»••'•
!'
Key words:
cancer,
Essiac,
herb-drug interactions, herbs, interactions, pharmacology, systematic review
T^ssiac
is a combination product of four herbs, including
J—/ burdock root, sheep sorrel, slippery
elm
bark, and Turkey
rhubarb. The exact formulation is
a
proprietary secret and has
been adjusted over the years. More than 40 essiac formula-
tions are available in the United Kingdom, Australia, and
North America.' For example, Flor-Essence is a combination
of
the
original four ingredients, along with blessed thistle, red
clover, kelp, and watercress. These additional ingredients were
added to theoretically potentiate the original compound.
Although Essiac is currently unavailable for sale in
Canada, the Canadian government allows Essiac to be sold
to patients on compassionate grounds. A survey conducted
in 2000 found almost 15% of Canadian women with breast
cancer to be using some form of essiac.-^ More recent sur-
veys and reviews reinforce Essiac's use among patients with
cancer.'"* The majority of the information available on Essiac
is from anecdotal sources or testimonials. Completed clini-
cal trials validating the use of the formulation are currently
lacking.
Essiac has been marketed and claimed to treat numerous
conditions. The aim of this systematic review is to evaluate
the evidence to determine the safety and efficacy of Essiac.
Adverse effects and toxicities may be anticipated based on
theoretical or empirical knowledge of the individual constit-
uents of the original formula, which include burdock root,
sheep sorrel, slippery elm bark, and Turkey rhubarb. This
review serves as a clinical support tool.
Catherine Ulbricht:
Massachusetts
General
Hospital,
Boston,
MA;
Wendy Weiss-
ner, and Nicole Giese: Natural Standard
Research
Collaboration,
Somerville,
MA;
Sadaf Hashnii:
Johns Hopkins School
oj
Hygiene
and
Public
Health,
Bal-
timore,
MD;
Tracée Rae
Abrams:
University
of
Rhode
Island,
Kingston,
RI;
Paul
Hammerness:
Harvard Medical
School,
Cambridge,
MA; Cynthia Dacey, Dana
A. Hackman, and Audrey Nealon:
Northeastern
University,
Boston,
MA; Jenny
Kim and Ruslan Voloshin:
Massachusetts College
of
Pharmacy,
Boston,
MA.
Reprint
requests:
Catherine Ulbricht, PharmD, Natural Standard
Research
Collaboration, One Davis Square, Somerville, MA 02140;
e-mail:
info@
naturalstandard.com.
DOI 10.2310/7200.2009.0010
© 2009 BC Decker Inc
DECKEI^
Methods
To prepare each Natural Standard review (<http://www.
naturalstandard.com>), electronic searches are conducted
in 10 databases, including AMED,
CANCERLIT,
CINAHL,
CISCOM,
the Cochrane Library, EMBASE,
HerbMed,
International Pharmaceutical Abstracts, Medline, and
M4PiML£i?rthrough December
2008.
Search terms include
all of the common names, scientific names, and listed
Journal
of the Society for
Integrative
Oncology,
Vol
7,
No 2
(Spring),
2009:
pp 73-80 73

74fournal of the Society for
Integrative
Oncology,
Spring
2009,
Volume
7,
Number
2
synonyms
for
each topic* Hand searches
are
conducted
of
20 additional journals
(not
indexed
in
common databases)
and
of
bibliographies from
50
selected secondary refer-
ences.
No
restrictions
are
placed
on the
language
or
quality
of publications. Researchers
in the
field
of
complementary
and alternative medicine
(CAM) are
consulted
for
access
to additional references
or
ongoing research.
All
literature
is collected pertaining
to
efficacy
in
humans (regardless
of
study designs, quality,
or
language), dosing, precautions,
adverse effec s,
use in
pregnancy
and
lactation, interactions.
alteration
of
laboratory assays,
and
mechanisms
of
action
(in vitro, animal research, human data). Standardized inclu-
sion
and
exclusion criteria
are
used
for
selection
of
evidence
used
to
determine the grades
for
effectiveness (Table
1).
Data
extraction
and
analysis
are
performed by health care profes-
sionals conducting clinical work and/or research
at
academic
centers using standardized instruments that pertain
to
each
review sectioi (defining inclusion
and
exclusion criteria
and
analytic tech liques, including validated measures
of
study
quality). Data
are
verified
by a
second reviewer. Blinded
review
is
conducted
by
multidisciplinary research-clinical
faculty
at
major academic centers with expertise
in
epide-
miology
and
research,
and
ment,
a
three-member panel of the editorial board addresses
conflicts
and
High-quality
reviews,
efficacy
or
lacking
in
high-quality
the
biostatistics, pharmacology, toxicology,
CAM
clinical practice.
In
cases
of
editorial disagree-
consults experts when applicable.
The
authors
of studies
are
contacted when clarification
is
required.
Results
Efficaq^
human trials (meta-analyses, systematic
randomized controlled trials) that would suggest
:k
of
efficacy
for
Essiac
for any
condition were
available literature.'
In the
absence
of
these
trials,
evidence from surveys, epidemiologic
studies, basic science, animal studies,
and
theory
was col-
lected
to
assess Essiac's clinical profile. Only
one
condition
(cancer)
had
enough preciinical supportive data
to
discuss
and
was
graded
"C" for
unclear
or
conflicting efficacy
(see
Table
1 for a
description
of
grades). Literature review
did
not suggest supportive evidence
for
other traditional uses
of
Essiac.
Historical
or
Theoretical Indications
that
Lack
Sufficient
Evidence
Essiac
and
essiac formulations have been traditionally
or his-
torically used
for
adenocarcinoma, acquired immune defi-
ciency syndrome (AIDS), appetite stimulation, arthritis,
asthma, blood cleansing, chelating, chronic fatigue syndrome,
detoxification, diabetes, energy enhancement, Hodgkin
dis-
ease,
immune system enhancement (cell repair), increasing
well-being, increasing life span, lupus, Lyme disease, paralysis,
reduction of chemotherapy side effects, and thyroid disorders.
Quality of
Scientific
Evidence:
Cancer
-
Crade
C
A Canadian study showed that 62%
of
cancer patients used
CAM therapy, among which essiac
was
listed
as one of
the
top
therapies used
by
these patients.^ Despite popular
use,
Ernst
and
Cassileth noted
in a
review that essiac
did
not offer reasonable hope
for the
treatment
of
cancer
but
may
be
promising
in
terms
of
cancer prevention.* Several
unpublished investigations, anecdotal
and
case reports,
and
indirect evidence
for
anticancer activity
of
constituent herbs
of Essiac have been presented.""*''"
An in
vitro study
in
rats showed that essiac preparations
may be
able
to
inhibit
tumor cell growth while enhancing
the
immune response
to antigenic stimulation. This may
be
especially valuable
in
immunosuppressed individuals.'" However, animal stud-
ies
of
Essiac (prepared
by
Caisse)
in the
1970s
at
Memorial
Sloan-Kettering Cancer Center
and a
more recent
in
vitro
*Essiac
synonyms/common
names/related
substances;
Burdock
root:
Akujitsu, anthraxivore, arctii, Arctium minus, Arctium
tomentosa,
bardana, Bardanae Radix,
bardane, bardane grande (French), beggar's buttons, burdock root, burr, burr seed, chin, clotbur, clot-burr, cocklebur, cockle button, cocklebuttons, cuckold,
daiki kishi, edible burdock, fox's dote, grass burdock, great
bur,
great burdock, great burdocks, gobo (Japan), grosse Klette (German), happy major, bardock,
hare burr, hurrburr, Kletterwurzel (German), lampazo (Spanish), lappola, love leaves,
niu
bang
zi, oil of
lappa, personata, Philanthropium, thorny burr,
Turkey burrseed, woo-bang-ja, wild gobo. Rhubarb: Baoshen pill. Canton rhubarb, Chinese rhubarb, chinesischer Rhabarber (German), chong-gi-huang,
common rhubarb, da-huang.
Da
Huang,
Da
huang Liujingao, daio, English rhubarb, Extractum Rhei Liquidum, Himalayan rhubarb, Indian rhubarb, Japa-
nese rhubarb, Jiang-
Zhi
Jian-Fel
yao
(JZJFY), Jinghuang tablet, medicinal rhubarb,
pie
rhubarb, Polygonaceae (family), Pyralvex, Pyralvex Berna, racine
de
rhubarbee (French),
RET
(rhubarb extract tablet), rhabarber, rhei radix, rhei rhizoma, rheum. Rheum
australe.
Rheum
B,
Rheum emodi. Rheum emodi Wall,
Rheum
officinale
Baill, Rheum
raponticum.
Rheum
rhaponticum.
Rheum tanguticum Maxim, Rheum tanguticum Maxim, ex.
Balf.,
Rheum tanguticum Maxim
L.,
Rheum
x
cultorum. Rheum rhabarbarum. Rheum undulatum. Rheum webbianum (Indian
or
Himalayan rhubarb), rheirhubarbe
de
chine (French), rubarbo,
ruibarbo (Spanish), shenshi rhubarb,
tai
huang, Turkey rhubarb, Turkish rhubarb. Sheep sorrel: Acedera, acid sorrel, azeda-brava, buckler
leaf,
cigreto,
com-
mon sorrel, cuckoo sorrow, cuckoo's meate, dock, dog-eared sorrel, field sorrel, French sorrel, garden sorrel, gowke-meat, greensauce, green sorrel, herba
acetosa, kemekulagi, Polygonaceae (family),
red
sorrel,
red top
sorrel, round leaf sorrel, Rumex
acetosa
L,
Rumex
acetosella
L,
Rumex scutatus, sheephead
sorrel, sheep's sorrel, sorrel dock, sour dock, sour grass, sour sabs, sour sauce, sour suds, Wiesensauerampfer, wild sorrel. Slippery
ebn
bark: Indian
elm,
moose elm,
red
elm, rock elm, slippery elm, sweet elm, Ulmaceae (family), Ulmusfulva, Ulmi
rubrae
cortex, Ulmusfulva Michaux, Ulmus
rubra,
winged
elm.

Table 1. Natural Standard Grading Scale
Level of Evidence Grade
Ulbricht
et
al,
Essiac
75
Criteria
A (strong scientific evidence)
B (good scientific evidence)
C (unclear
or
conflicting scientific evidence)
D (fair negative scientific evidence)
F (strong negative scientific evidence)
Statistically significant evidence
of
benefit from
> 2
properly randomized controlled
trials (RCTs), OR evidence from one properly conducted RCT AND one properly
conducted meta-analysis, OR evidence fi-om multiple RCTs
with!
a
clear majority
of
the
properly conducted trials showfing statistically significant evidence
of
benefit AND v^^ith
supporting evidence
in
basic science, animal studies,
or
theory.
Statistically significant evidence
of
benefit from
1-2
properly randomized trials, OR
evidence
of
benefit from
>
1
properly conducted meta-analysis, OR evidence
of
benefit
from
>
1
cohort/case-control/nonrandomized trials AND with supporting evidence
in
basic science, animal studies,
or
theory.
This grade applies
to situations in which
a
well-designed
RCT
reports negative results
but
stands in
contrast to
the positive
efficacy results
of multiple
other less well-designed trials
or
a
well-designed
meta-analysis,
while
awaiting
confirmatory
evidence from an additional
well-designed
RCT.
Evidence
of
benefit frorri
>
1
small RCT(s) without adequate size, povifer, statistical
significance,
or
quality
of
design by objective criteria,* OR conflicting evidence from
multiple RCTs without
a
clear majority
of
the properly conducted trials showing evi-
dence
of
benefit
or
ineffectiveness, OR evidence
of
benefit from
>
1
cohort/case-control/
nonrandomized trials AND without supporting evidence
in
basic science, animal stud-
ies,
oi"
theory, OR evidence
of
efficacy only from basic science, animal studies,
oi"
theory.
Statistically significant negative evidence (ié, lack
of
evidence
of
benefit) from cohort/
case-control/nonrandornized
trials,
AND evidence
in
basic science, animal studies,
or
theory suggesting
a
lack
of
benefit.
This grade also applies
to situations in which >
1 well-designed
RCT
reports negative
results,
notwithstanding
the existence
of
positive efficacy results
reported from
other less
well-
designed trials or a
meta-analysis.
(Note:
if
there are > 1 negative RCTs
that
are well
designed
and
highly
compelling,
this will
result
in
a grade
of'F"
notwithstanding positive
results from
other less well-designed
studies.)
Statistically significant negative evidence (i.e. lack
of
evidence
of
benefit) from
>
1
properly
randomized adequately powered trial(s)
of
high-quality design by objective criteria.*
Adapted from Natural Standard. Available at: http://www.naturalstandard.com. (accessed February 2009)
Grades reflect the level
of
available scientific evidence
in
support
of
the efficacy
of
a
given therapy
for a
specific indication. Expert opinion and folkloric
precedent are
not
included
in
this article. Evidence
of
harm is considered separately; the grades apply only to evidence
of
benefit.
*Objective criteria are derived from validated instruments
for
evaluating study quality, including the
5-point
scale developed by Jadad and colleagues,
in
which
a
score below 4 is considered
to
indicate lesser quality methodologically."
Study found no significant effects on tumor growth or anti-
proliferative effects in prostate cancer cells." In addition,
there are a lack of prospective, randomized, controlled trials
evaluating the safety and effectiveness of essiac therapy in
adults or children suffering from any form of cancer.'"'*"
Evidence from a retrospective cohort study did not show
improvement in quality of life or mood states in patients
with cancer using Essiac."
Different brands may contain variable ingredients, and
the comparative effectiveness of these formulas is not known.
None of the individual herbs used in Essiac have been tested
in rigorous human cancer trials (rhubarb has shown some
antitumor properties in animal experiments; slippery elm
inner bark has not; sheep sorrel and burdock have been
used traditionally in cancer remedies). Numerous individual
patient testimonials and reports from manufacturers are
available on the Internet, although these cannot be consid-
ered scientifically viable as evidence." Essiac is probably safe
within certain guidelines but is not known to be effective if
taken before, during, or after treatment for cancer. Thus,
individuals with cancer are advised not to delay treatment
with more proven therapies. Suggestions for future research
include in vivo study and/or higher quality human trials that
evaluate Essiac's ability to infiuence clinical outcomes, such
as cancer recurrence.
Adverse Effects
Allergy
Avoid if there is a known allergy or hypersensitivity to
the constituents of Essiac, rhubarb, sheep sorrel {Rumex
acetosa
L.), slippery elm bark, or burdock. Rhubarb leaf is

76
Journal
of the Society for
Integrative
Oncology,
Spring
2009,
Volume
7,
Number
2
commonly known
for its
toxic effect
and
anaphylaxis
has
been reported after rhubarb leaf
ingestion.
Allergy
is
possible
in patients taking Essiac products contaminated with
rhu-
barb
leaf,
although
the
traditional Essiac preparation does
not contain rhubarb
leaf.
Anecdotal reports
of
allergic reac-
tions
to
oral products containing sorrel exist.^" Sheep
sor-
rel
may
cause
hay
fever during harvesting.^' Although rare,
urticaria
has
pccurred following contact with slippery
elm
outer bark."
Gardiovascular
Atropine-likereactions such
as
bradycardia have been
reported following consumption
of
burdock products,
which
may
have been contaminated with belladonna alka-
loids."""
Arrhythmias, cardiac toxicity,
and
neuromuscular
dysfunction have been reported with chronic
use of rhu-
barb,
which
may be due to
hypokalemia, secondary
to its
cathartic effedts.^'
Dermatolonc
has been associated with burdock root,
:,
and
rhubarb
Contact dern atitis
slippery elm bark
Endocrine
Estrogenic effects have been associated with oral burdock
by human immunodeficiency virus
(HIV)
consumption
patients.^" Based
on
animal study using streptozocin-
induced diabetic mice, burdock
may
aggravate diabetic
conditions
in
mice,^' which stands
in
opposition
to its
traditional role
as
having hypoglycémie effects.^^ Based
on
a report
of
sheep sorrel, hypocalcemia
may
occur owing
to
the binding
of
oxalate
to
calcium with consequent precipi-
tation."
The
¿»ccurrence
of
tetany
is
attributed
to the com-
bination
of
ionic calcium with oxalic acid.-''' Chronic
use of
rhubarb
may
:ause electrolyte loss (particularly potassium)
and hyperaldosteronism.
Gastrointestinal
Transient nausea, vomiting,
and
diarrhea
may
occur with
the adniinistration
of
Essiac
if
ingested around meals."
Sorrel
and
rhubarb's oxalate content exerts corrosive effects
on
the
digestive tract. According
to a
review
of
oxalate-
containing plants, such
as raw
rhubarb, large amounts
may
cause burning pain
in the
esophagus
and
epigastrium,
nau-
sea, diarrhea.
ties
in
slippeiy
elm but may
pose
a
risk with large doses.
Spasmodic cramps
or
watery diarrhea
may be
seen with
short-term
use of
rhubarb, whereas chronic
use may
cause
and colic.''' Oxalate
is
present
in low
quanti-
inhibition
of
gastric motility, pseudomelanosis coli, colic,
and atonic colon. Fluid
and
electrolyte loss, particularly
hypokalemia,
has
also been associated with
the
ingestion
of rhubarb.
In
theory, anthraquinones
in
rhubarb root
or
sheep sorrel
may
lead
to
diarrhea, dehydration,
or
loss
of
electrolytes (such as potassium)
and
may increase
the
effects
of agents with possible laxative properties."
The
inner bark
of slippery
elm is
rich
in
mucilage, consisting
of
insoluble
polysaccharides (hexose, pentose, rnethylpentose), which
form
a
viscous material following oral administration
or
when used topically." Owing
to its
high mucilage content,
slippery elm inner bark may be
a
safe herbal remedy
to
treat
irritations
of the
skin
and
mucous membranes. Although
allergic reactions after contact have been reported, there
is
no known toxicity with typical dosing when products made
only from
the
inner bark
are
used.
Genitourinary
Increased micturition may occur with the use of Essiac. Based
on
in
vitro animal study, short-term
use of
anthraquinones,
which are present
in
rhubarb, may cause uterine contraction
at high concentrations," although
the
clinical significance
of
this effect
is
unclear.
Hepatic
Extensive hepatic necrosis, severe metabolic acidosis with
subsequent hepatic failure,
and
neonatal jaundice have
been reported from ingestion
of
large amounts
of
sorrel
or
rhubarb."'''^
Musculoskeletal
In theory, muscular weakness
or
accelerated bone deteriora-
tion may occur with chronic
use of
rhubarb."'''
Neurologic/Central Nervous
System
Headache
has
been anecdotally reported with
the use of
Essiac. Ingestion
of
rhubarb leaf
may
cause seizures
and
anthraquinone overdose
is
possible."
Pulmonary/Respiratory
Sorrel's pollen is
a
potential trigger
for
allergic rhinitis, bron-
chial asthma,
and
hypersensitivity reactions of the upper
air-
ways.^"
However,
any
pollen would
be a
potential trigger
for
those harvesting.
Renal
Diuretic effects have been associated with oral burdock
use
in
HIV.
patjents.'" Urolithiasis
and
nephrosis
may
result

Ulbricht
et
al,
Essiac
77
from the systemic absorption of oxalates and can conse-
quently lead to proteinuria, oliguria, and anuria.^"* Oxalic
acid adheres to calcium in blood, forming insoluble calcium
oxalate crystals that may be deposited in the kidneys, con-
sequently leading to renal stones. There are also anecdotal
reports of polyuria as
a
possible side effect of sorrel ingestion.
Discoloration of urine, bright yellow or red, may occur with
rhubarb ingestion. Chronic use of rhubarb, or its anthraqui-
none derivatives, may also lead to nephropathies, albuminu-
ria, or hematuria.^' However, this stands in opposition to
many animal and human studies, including reviews, that
note the positive effects of rhubarb use to improve chronic
renal failure and uremia short
Systemic
Anticholinergic effects have been observed in HIV patients
taking burdock root.^° Multiple other reports of anticholin-
ergic reactions have been reported following consumption
of burdock products, which are thought to have been con-
taminated with belladonna alkaloids."""
Interactions
In general, there is a lack of human safety and efficacy data
for Essiac. Essiac and essiac-like formulations may theoret-
ically interact with any oral agent owing to the possibility
of altered pharmacokinetics. Drug and herb interactions
are primarily based on theoretical or empirical knowledge
of the individual constituents or from in vitro data on
Essiac and Flor-Essence. Listed interactions include posi-
tive,
synergistic, and negative interactions, and references
are provided when available; this is not a comprehensive
list. Owing to the lack of detailed reporting of scientific
herbal names in the available literature, this report does not
attempt to clarify what particular species was used if not
stated in the original research. This is a common challenge
in herb and supplement research, and care should be taken
in future studies to clarify the scientific name for each com-
mon herbal name.
Interactions with Herbs, Supplements, or Agents Based on
Sorrel
Antibiotics," hepatotoxic agents,*'' iron," licorice," neph-
rotoxic agents, rhubarb, shamrock, and steroidal herbs." In
theory, precipitation of some drugs may occur when taken
concomitantly with sorrel"; therefore, separate administra-
tion is recommended.
Interactions with Herbs, Supplements, or Agents Based on
Burdock
Estrogens and phytoestrogens,'" insulin and oral hypoglycé-
mie agents,'''^^'""*' and oral contraceptives.'"
Interactions with Herbs, Supplements, or Agents Based on
Essiac and Essiac-Like Formulas
Agents metabolized via the cytochrome P-450 enzyme
system (most notably CYP1A2 and CYP2C19),«* alkaloid
agents," ACE inhibitors,''^ antiarrhythmic agents,"" anti-
neoplastic agents, antioxidants,**'"'" antiplatelet and anti-
coagulant agents,""^"'" antipsychotic agents," atropine,"
belladonna," blessed thistle, burdock,^" cardiac-active herbs
(calamus, cereus, cola, coltsfoot, devil's claw, European
mistletoe, fenugreek, fumitory, ginger, Panax
ginseng,
haw-
thorn, white horehound, mate, parsley, quassia, scotch
broom flower, shepherd's purse, and wild carrot), cardiac
glycosides (foxglove),'"•'° cat's claw, chemotherapy agents,
cisplatin," corticosteroids,"'" diuretics," ephedra," gold-
enseal," Glauber's salt (mirabilite),''' hyoscyamine," immu-
nomodulators,** iron," kelp, minerals (calcium, iron, and
zinc),"
red clover, stimulant laxative herbs (aloe dried leaf
sap,
blue flag rhizome, alder buckthorn, European buck-
thorn, butternut bark, cascara bark, castor oil, colocynth,
fruit pulp, gamboges bark exudates, jalap root, black root,
manna bark exudates, podophyllum root, senna leaves
and pods, wild cucumber fruit, and yellow dock root),""
watercress, and valerian."
Interactions with Herbs, Supplements, or Agents Based on
Rhubarb
Alismatics orientalis,'*'' angiotensin-converting enzyme
(ACE) inhibitors,'''»^ antacids, calcium,""** captopril,''''""'"«
cardiac glycosides,"'""''" chlorhexidine," digoxin,'"'" diuret-
ics,"
horsetail," iron,"'''' jimsonweed, laxatives," leeches,"
licorice," nephrotoxic agents," nifedipine,'* potassium-
depleting diuretics,"" sage,'' sanchi powder,* senna,''' steroi-
dal agents," and zinc."
Conclusion
There is a lack of both human safety and efficacy data for
Essiac and essiac formulations. Consumers should be aware
that there are many varieties of essiac formulas and only
one trademarked Essiac, the formula of which is unknown.
Adverse effects and interactions may occur from any of the
constituents. Well-designed trials testing Essiac and assessing
clinical outcomes such as cancer recurrence are necessary to
draw stronger conclusions.

78
Journal
of the Society for
Integrative
Oncology,
Spring
2009,
Volume
7,
Number 2
Acknowledgment
sclosure of authors and reviewers: None
Financial d
reported.
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