The Use of Garcinia Extract (Hydroxycitric Acid) as a Weight loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials

Abstract

The aim of this systematic review is to examine the efficacy of Garcinia extract, hydroxycitric acid (HCA) as a weight reduction agent, using data from randomised clinical trials (RCTs). Electronic and nonelectronic searches were conducted to identify relevant articles, with no restrictions in language or time. Two independent reviewers extracted the data and assessed the methodological quality of included studies. Twenty-three eligible trials were identified and twelve were included. Nine trials provided data suitable for statistical pooling. The meta-analysis revealed a small, statistically significant difference in weight loss favouring HCA over placebo (MD: -0.88 kg; 95% CI: -1.75, -0.00). Gastrointestinal adverse events were twice as common in the HCA group compared with placebo in one included study. It is concluded that the RCTs suggest that Garcinia extracts/HCA can cause short-term weight loss. The magnitude of the effect is small, and the clinical relevance is uncertain. Future trials should be more rigorous and better reported.

Full text

Hindawi Publishing Corporation
Journal of Obesity
Volume 2011, Article ID 509038, 9pages
doi:10.1155/2011/509038
Review Article
The Use of
Garcinia
Extract (Hydroxycitric Acid) as a
Weight loss Supplement: A Systematic Review and Meta-Analysis
of Randomised Clinical Trials
Igho Onakpoya, Shao Kang Hung, Rachel Perry, Barbara Wider, and Edzard Ernst
Peninsula Medical School, University of Exeter, Devon EX2 4NT, UK
Correspondence should be addressed to Igho Onakpoya, igho.onakpoya@pcmd.ac.uk
Received 13 May 2010; Revised 13 July 2010; Accepted 22 October 2010
Academic Editor: S. B. Heymsfield
Copyright © 2011 Igho Onakpoya et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
The aim of this systematic review is to examine the efficacy of Garcinia extract, hydroxycitric acid (HCA) as a weight reduction
agent, using data from randomised clinical trials (RCTs). Electronic and nonelectronic searches were conducted to identify relevant
articles, with no restrictions in language or time. Two independent reviewers extracted the data and assessed the methodological
quality of included studies. Twenty-three eligible trials were identified and twelve were included. Nine trials provided data suitable
for statistical pooling. The meta-analysis revealed a small, statistically significant difference in weight loss favouring HCA over
placebo (MD: −0.88 kg; 95% CI: −1.75, −0.00). Gastrointestinal adverse events were twice as common in the HCA group
compared with placebo in one included study. It is concluded that the RCTs suggest that Garcinia extracts/HCA can cause short-
term weight loss. The magnitude of the effect is small, and the clinical relevance is uncertain. Future trials should be more rigorous
and better reported.
1. Introduction
The prevalence of overweight and obesity has increased over
the last decade [1], and current measures have not been
able to stem the tide. A wide variety of weight management
strategies are presently available, and some involve the use
of dietary supplements marketed as slimming aids. One
such slimming aid is Garcinia extract, (-)-hydroxycitric acid
(HCA).
HCA is a derivative of citric acid and can be found in
plant species native to South Asia such as Garcinia cambogia,
Garcinia indica, and Garcinia atroviridis [2]. HCA is usually
marketed as a weight loss supplement either alone or in
combination with other supplements [2,3]. Some authors
have suggested that HCA causes weight loss by competitively
inhibiting the enzyme adenosine triphosphatase-citrate-lyase
[3–6]. HCA has also been reported to increase the release
or availability of serotonin in the brain, thereby leading to
appetite suppression [7]. Other postulated weight loss mech-
anisms include inhibition of pancreatic alpha amylase and
intestinal alpha glucosidase, thereby leading to a reduction
in carbohydrate metabolism [8].
Animal studies have suggested that HCA causes weight
loss [3,9], and human trials involving the use of HCA as a
weight loss supplement have been carried out [3].
Theprimaryobjectiveofthissystematicreviewwasto
examine the efficacy of HCA in reducing body weight in
humans, using data from randomised clinical trials.
2. Methods
Electronic searches of the literature were conducted in the
following databases: Medline, Embase, TheCochraneLibrary,
Amed, and Cinahl. The search terms used included dietary
supplements, antiobesity agents, body weight, hydroxyci-
trate, garcinia, and derivatives of these. Each database was
searched from inception until March, 2010. We also searched
the Internet for relevant conference proceedings and hand
searched relevant medical journals, and our own files. The
bibliographies of all located articles were also searched.

2Journal of Obesity
•
11 articles excluded for the following reasons:
•HCA as part of a combination package: 6
•Unblinded trial: 1
•Single-blinded trial: 1
•Duplicates: 2
•Didn’t measure body weight: 1
12 randomised clinical
trials included
23 full texts/abstracts retrieved
for more detailed evaluation of
the articles
5002 references retrieved
4979 articles excluded based on title/abstract, mainly
because they did not investigate a food supplement for
weight loss or the study design was unsuitable
Figure 1: Flow chart showing the process for the inclusion of randomised controlled trials.
Only randomised, double-blind, placebo-controlled
studies were included in this paper. To be considered for
inclusion, studies had to test the efficacy of oral HCA or
any of its salts for weight reduction in obese or overweight
humans. Included studies also had to report body weight
as an outcome. No age, time, or language restrictions were
imposed for inclusion of studies. Studies which involved
the use of HCA as part of a combination treatment (dietary
interventions containing other supplements in addition to
HCA), or not involving obese or overweight subjects based
on body mass index (BMI) values, were excluded from this
paper.
Two independent reviewers assessed the eligibility of
studies to be included in the paper. Data were extracted
systematically by two independent reviewers according to
the patient characteristics, interventions, and results. The
methodological quality of all included studies was assessed
by the use of a quality assessment checklist adapted from
the Consolidated Standard of Reporting Trials (CONSORT)
guidelines [10,11]. In addition, the Jadad score [12] was also
used to assess the quality of included studies. Disagreements
were resolved through discussion with the other authors.
Data are presented as means with standard deviations.
Mean changes in body weight were used as common
endpoints to assess the differences between HCA and placebo
groups. Using the standard meta-analysis software [13], we
calculated mean differences (MDs) and 95% confidence
intervals (CIs). Studies included in the meta-analysis were
weighted by SD (a proxy for study size). If a trial had 3
arms, only the HCA and placebo arms were included in the
meta-analysis. The I2statistic was used to assess for statistical
heterogeneity amongst studies. A funnel plot was used to test
for publication bias.
3. Results
Our searches produced 5002 “hits” of which 23 potentially
relevant articles were identified (Figure 1). Six trials were
excluded because they involved the use of HCA in combina-
tion with other therapies [7,14–18]. One trial was excluded
because it was not blinded [19], and another because it
was single blinded [20]. Two articles were excluded because
they were duplicates. One of these articles [21] was the
same trial published in another journal which had been
earlier excluded, while the other article [22]wasareportof
two individual trials which were included in this systematic
review. One trial was excluded because the investigators did
not measure weight as an outcome [23]. Thus 12 randomised
clinical trials (RCTs) including a total of 706 participants met
our inclusion criteria, and were included in this systematic
review [2,4–6,24–31]. Their key details are summarized in
Tab l e s 1,2,and3.
All of the studies had one or more methodological
weaknesses (Tabl e 1 ). None of the included studies reported
on how double blinding was carried out, and all studies
were also unclear about how the allocation was concealed.
The randomization procedure was clear in only a third of
included studies [4,6,25,29].
ThreeRCTs[4,28,31] did not provide actual values
to enable statistical pooling (Tabl e 3 ). One of these RCTs

Journal of Obesity 3
Tab le 1: Characteristics of included studies.a
Authors
Year Main outcome (s) Main diagnoses
of participants
Randomisation
appropriate?
Allocation
concealed?
Groups
similar at
baseline?
Similar
follow-up of
groups?
Outcome
assessor
blinded?
Care
provider
blinded?
Patients
blinded?
Attrition
bias?
ITT
analysis?
Jadad
Score
Hayamizu et al.
2001 [24]
Visceral fat, BW
indices
Overweight
subjects ? ? + + ???
−− 2
Hayamizu et al.
2003 [4]
Visceral fat, BW
indices
Overweight
subjects + ? + + ????
−3
Heymsfield et al.
1998 [25]BW, fat mass Overweight
subjects + ? + + ????+5
Kovacs et al. 2001
[26]
Satiety, food
intake, BW
Normal to
moderately
obese subjects
? ? ? + ???
−− 3
Kovacs et al. 2001
[27]
Satiety, food
intake, BW
Normal to
moderately
obese subjects
? ? ? + ???
−− 3
Mattes and
Bormann 2000 [5]
Satiety, body
composition
Overweight
subjects ? ? + + ????
−2
∗Preuss et al. 2002
[28]
BW, BMI,
appetite
Moderately
obese subjects ? ? ? ? ?????2
Preuss et al. 2004
[29]
BW, BMI, lipid
profile, appetite
Healthy, obese
volunteers + ? + + ????
−3
Preuss et al. 2004
[6]
BW, BMI, lipid
profile, appetite
Healthy, obese
volunteers + ? ? + ????
−4
Ramos et al. 1995
[30]BW, BMI, lipids Obese subjects ? ? ? ? ? ? ? ? ? 2
Roongpisu-
thipong et al. 2007
[2]
BW, BMI, BP,
waist-hip ratio
Healthy,
overweight
volunteers
? ? + + ????
−2
Thom 1996 [31]
BW, BP, total
cho-sterol,
appetite
Obesesubjects? ????????2
aQuality assessment checklist adapted from The CONSORT Statement and Jadad criteria [10–12].

4Journal of Obesity
Tab le 2: Results table for studies with adequate data for meta-analysis.b
Author
Year
Country
HCA
formulation
Randomised/
Analysed Age in yrs HCA Dosage Treatment
Duration
Baseline weight
indices for
HCA/placebo groups
Mean change in
weight indices for
HCA/placebo groups
Adverse
events (AE)
Control for
lifestyle factors
Hayamizu et al.
2001 Japan [24]Tablets 40/40
37.1±12.5
(HCA)
36.5±10.7
(PLA)
1 g daily 8 weeks
BW:
75.6±10.3/73.3±10.7
BMI:
27.9±1.8/27.8±1.8
BW:
0±11.5/0.5±11.7
BMI:
0±1.97/0.3±2.3
No serious
AE reported Dietary control
Heymsfield et al.
1998 U.S.A. [25]Capsules 135/135
38.6±7.7
(HCA)
39.4±7.2
(PLA)
1.5 g daily 12 weeks
BW:
83.8±10.7/88.2±13.0
BMI:
31.2±2.8/31.9±3.1
BW:
−3.2±3.3/−4.1±3.9
Headache,
URTI & GI
symptoms
High fibre diet,
stable physical
activity levels
Kovacs et al. 2001
Netherlands [26]Unspecified 21/21
43 ±10
for both
HCA&placebo
groups
1.5 g daily 2 weeks
Mean BW:
79.3±9.0
Mean BMI:
27.6±2
BW:
−0.4±0.9/−0.5±1.4Not reported
No restriction on
food intake; 1 glass
of alcohol
maximum daily
∗§Kova cs e t al .
2001 Netherlands
[27]
Unspecified 11/11
47 ±16
for both
HCA&placebo
groups
1.5 g daily 2 weeks
Mean BW:
85.4±25.8
Mean BMI:
27.4±8.2
BW:
−1.5±1.66/
−1.0±1.34
Not reported
No restriction on
food intake; 1 glass
of alcohol
maximum daily
Mattes and
Bormann 2000
U.S.A. [5]
Caplets 167/89
40.97 ±10
(HCA)
44.0±9.5
(PLA)
1.2 g daily 12 weeks
BW:
75.5±10.2/75.8±12.6
BMI:
28.3±0.6/28.8±0.7
BW:
−3.7±3.1/−2.4±2.9Not reported
Dietary control,
exercise
encouraged, but no
formal regimen
prescribed
§Preuss et al. 2004
India [29]Unspecified 60/53 Range: 21–50 2.8 g daily 8 weeks
BW:
91.7±15.7/80.4±36.9
BMI:
34.7±5.5/32.5±2.6
BW:
−4.5±16.6/
−1.6±34.1
BMI:
−1.7±5.8/−0.7±2.74
Gas, stomach
burn,
headache,
skin rash
Dietary control,
walking exercise
programme
§Preuss et al. 2004
India [6]Unspecified 30/29 Range: 21–50 2.8 g daily 8 weeks
BW:
88.5±21.8/87.4±15.9
BMI:
33.6±6.2/34.0±4.5
BW:
−5.5±23.7/
−1.4±17.3
BMI:
−2.1±6.85/−0.5±4.8
No serious
AE reported
Dietary control,
walking exercise
programme
Ramos et al. 1995
Mexico [30]Capsules 40/ 35
35.3±11.8
(HCA)
38.7±12.3
(PLA)
1.5 g daily 8 weeks BMI:
32.6±4.3/33.2±4.4
BW:
−4.1±1.8/−1.3±0.9
Nausea,
headache Dietary control
Roongpisu-
thipong et al. 2007
Thailand [2]
Sachets 50/42
40.0±10.0
(HCA)
36.0±10.0
(PLA)
Unclear 8 weeks
BW:
69.0±5.0/65.0±5.0
BMI:
27.5±1.0/26.7±2.5
BW:
−2.8±0.5/−1.4±0.5
BMI:
−0.9±1.0/−0.6±1.0
Not reported Dietary control
Abbreviations: HCA: Hydroxycitric acid; PLA: Placebo; BW: Body Weight; BMI: Body Mass Index.
bUnless otherwise specified, values for age, baseline weight and mean change in weight indices have been reported as means with standard deviations.
∗Studies included as crossover design, otherwise all included trials had parallel-study design.
§Studies with 3 intervention groups.

Journal of Obesity 5
Tab le 3: Results of included studies without suitable data for meta-analysis.ρ
Author
Year
Country
HCA
formulation
Randomised/
Analysed Age in yrs HCA
Dosage
Treatment
Duration
Baseline weight
indices for
HCA/placebo
groups
Main Results
Adverse
events
(AE)
Control
for lifestyle
factors
Hayamizu
et al. 2003
Japan [4]
Tablets 44/39
43.7±11.9
(HCA)
45.2±13.0
(PLA)
1 g daily 12 weeks
BW:
75.1±12.3/
75.9±11.5
BMI:
28.9±4.7/
28.5±4.6
No significant
differences in
BMI or body
weight at week 12
Common
cold,
toothache,
diarrhea
Dietary
control
Preuss et al.
2002
(abstract)
India [28]
Unspecified 48/unclear Not
reported 2.8 g daily 8 weeks Not reported
4.8% loss in body
weight, and 6.8%
decrease in BMI
for HCA group
Not
reported
Diet
control,
exercise
Thom 1996
(abstract)
Norway
[31]
Capsule 60/unclear Not
reported 1.32 g daily 8 weeks Not reported
Significant
decrease in body
weight in HCA
group compared
with placebo
(P<.001)
Stomach
ache
Low fat
diet,
exercise
Abbreviations: HCA: Hydroxycitric acid; PLA: Placebo; BW: Body Weight; BMI: Body Mass Index.
ρUnless otherwise stated, all trials are parallel-study designs.
reported a nonsignificant difference in BMI or body weight
between groups [4], another reported a significant difference
(P<.001) in the HCA group compared with placebo [31].
The third RCT [28] reported a decrease in body weight and
(BMI) from baseline for the HCA group, without providing
results of intergroup differences.
A forest plot (random effect model) for studies with
data suitable for statistical pooling is shown in Figure 2.The
meta-analysis reveals a statistically significant difference in
body weight between the HCA and placebo groups. The
average effectsizewas,however,small(MD:−0.88 kg; 95%
CI: −1.75, −0.00), with a Pvalue of .05. This translates to
about 1% in body weight loss in HCA group compared with
placebo. The I2statistic suggests that there was considerable
heterogeneity amongst the trials, the duration of treatment,
and the dosages of HCA used in the different trials varied
widely. A funnel plot of mean difference plotted against trial
sample size (Figure 3) indicated that most of the studies
(which had small sample sizes) were distributed around the
mean difference of all the trials.
Sensitivity analyses were performed to test the robustness
of the overall analysis. The first included 7 trials [2,5,6,
24,25,29,30] with parallel-group design, excluding two
studies which were crossover [26,27]. Meta-analysis of these
trials revealed MD of −1.22 kg (95% CI: −2.29, −0.14).
Heterogeneity was substantial. A second meta-analysis for
studies with parallel group designs and dosage ranges of
HCAbetween1and1.5gperday[5,24,25,30] did not
reveal a significant difference between HCA and placebo;
heterogeneity was also substantial in this analysis. A third
meta-analysis excluding three studies with outlying data for
MD [6,29,30] did not reveal a significant difference in
weight loss between HCA and placebo, but heterogeneity
was considerable. A further meta-analysis of the two trials
with good methodological quality [6,25]revealedanon-
significant difference in weight loss (MD: 0.88 kg; 95% CI:
−0.33, 2.10) between HCA and placebo, with I2value of
0, suggesting that heterogeneity might not be important.
Finally, a meta-analysis of the change in BMI for four studies
[6,24,29,31] did not reveal any significant difference
between HCA and placebo (MD: −0.34 kg; 95% CI: −0.88,
0.20), with I2value of 0.
One study [2] reported a significant decrease in fat mass
in the HCA group compared with placebo (P<.05),
while two studies [4,24] reported a significant decrease in
visceral, subcutaneous, and total fat areas in the HCA group
compared with placebo (P<.001). In contrast two other
studies [5,25] found no significant difference in body fat loss
between HCA and placebo.
Adverse events reported in the RCTs included headache,
skin rash, common cold, and gastrointestinal (GI) symp-
toms. In most of the studies, there were no major differences
in adverse events between the HCA and placebo groups.
However, in one trial, GI adverse events were twice as
frequent in the HCA group compared with the placebo
group [25]. In total, there were 88 drop outs. A further 45
participants were reported to have been excluded from the
analysis in one trial [5] because they either took a mixture of
HCA and placebo (28), or were males (17).
4. Discussion
The objective of this systematic review was to assess the
efficacy and effectiveness of HCA as a weight reduction
agent. The overall meta-analysis revealed a small difference
in change in body weight between the HCA and placebo
groups. The effect is of borderline statistical significance and
is no longer significant on the basis of a sensitivity analysis

6Journal of Obesity
Study or subgroup
HCA
Mean SD Mean SDTotal
Placebo
Total Weight
Mean difference
IV, random, 95% CI
Mean difference
IV, random, 95% CI
Hayamizu 2001
Heymsfield 1998
Kovacs 2001a
Kovacs 2001b
Mattes 2000
Preuss 2004a
Preuss 2004b
Ramos 1995
Roongpisuthipong 2007
0
−3.2
−0.4
−1.5
−3.7
−4.5
−5.5
−4.1
−2.8
11.5
3.3
0.9
1.66
3.1
16.6
23.7
1.8
0.5
0.5
−4.1
−0.5
−1
−2.4
−1.6
−1.4
−1.3
−1.4
20
66
21
11
42
19
9
18
23
11.7
3.9
1.4
1.34
2.9
34.1
17.3
0.9
0.5
20
69
21
11
47
16
10
17
19
1.4%
14.7%
18%
14.4%
14.4%
0.2%
0.2%
16.6%
20%
−0.5[−7.69, 6.69]
0.9[−0.32, 2.12]
0.1[−0.61, 0.81]
−0.5[−1.76, 0.76]
−1.3[−2.55, −0.05]
−2.9[−21.2, 15.4]
−4.1[−22.93, 14.73]
−2.8[−3.74, −1.86]
−1.4[−1.7, −1.1]
Total (95% CI) 229 230 100% −0.88 [−1.75, −0] 0510
Favours HCA Favours placebo
−10 −5
Test for overall effect: Z=1.96 (P=.05)
Heterogeneity: τ2=0.98; χ2=38.5, df =8(P<.00001); I2=79%
Figure 2: Forest plot of comparison showing the effectofhydroxycitrateonbodyweight.Thevertical line represents no difference in weight
loss between HCA and placebo.
10
8
6
4
2
0
SE(MD)
−100 −50 0 50 100
MD
Figure 3: Funnel plot of the mean difference in body weight
reduction trials of HCA, plotted against sample size. The vertical
line depicts the weighted mean difference of all trials.
of rigorous RCTs. Arguably the overall effect size is also too
small to be of clinical relevance. The overall meta-analytic
result corroborates the findings from one of the studies
without suitable data for statistical pooling [31], but is at
variance with another study [4].
The overall result should be interpreted with caution.
The pooled data from some of the studies were adjusted
values. Three studies with small sample sizes [6,29,30]
seemed to have influenced the overall meta-analytic result in
favour of HCA over placebo. If these three trials are excluded,
the meta-analysis result is no longer significant. The largest
and most rigorous RCT [25] found no significant difference
in weight loss between HCA and placebo.
The result of our systematic review corroborates the
findings from a previous systematic review of weight loss
supplements, which reported that the weight reducing effects
of most dietary supplements is not convincing [32]. HCA
is a commonly marketed as a complementary weight loss
supplement. The meta-analysis from this systematic review
suggests that HCA is not as effective as conventional weight
loss pills, for example, orlistat. In a meta-analysis report of 16
studies including over 10 000 participants [33], overweight
and obese patients taking orlistat had a clinically significant
reduction in body weight compared to placebo (MD: 2.9 kg;
95% CI: 2.5, 3.2). Participants taking orlistat achieved a 5%
and 10% weight loss compared to placebo in the results from
pooled data. This contrasts quite sharply with the results
from the meta-analysis of HCA clinical trials.
All of the studies included in this review had method-
ological issues, which are likely to have affected the outcomes
in these trials. This is supported by the I2values from
the overall meta-analysis result which suggested substantial
heterogeneity. Most of the studies included in this systematic
review had small sample sizes. Only one included study [25]
reported that they performed a power calculation. Larger
study sizes with apriorisample size calculation will help
eliminate a type II error (i.e., failure to reject the null
hypothesis when it should have been rejected).Only one
study [25] performed an intention to treat (ITT) analysis,
while all the participants in three other studies [24,26,27]
were reported to have completed the trial. The failure of
about 66% of the included studies to report ITT analyses
casts a doubt as to the validity of their results. In several of
the RCTs, drop-outs/attrition was unclear. In one study [5],
participants were excluded due to mixed-pill ingestion (an
error in coding of pill bottles resulted in some participants
receiving a mixture of HCA and placebo). Male participants
were also excluded from the analysis of this RCT because they
were too few in number compared with females in the trial.
It was also unclear to which intervention group the excluded
participants belonged to in this study.
The dosage of HCA, and the duration of study also varied
amongst the RCTs. The dosage of HCA used ranged from
1 g to 2.8 g daily. The optimal dose of HCA is currently
unknown. Two included studies which differed widely in
results [25,29] also differed widely in dosage of HCA.

Journal of Obesity 7
Dose effectofHCAonbodyweight
0.5
−0.9
−0.1
0.5
1.3
2.9
4.1
2.8
−2
−1
0
1
2
3
4
5
0 0.5 1 1.5 2 2.5 3
Dosage (g)
Weight loss (kg)
Figure 4: Effect of dosage of HCA on body weight. The dosages
from included RCTs did not produce a linear effect on body weight.
Though one of these studies claimed the bioavailability of
the HCA used in their trial was high [25], the dosage of
HCA used was almost twice that used in the other trial [29].
It is not clear if the higher HCA dosage ensures a higher
bioavailability of HCA. A nonlinear, significant (P<.05)
correlation between the dosage of HCA and body weight loss
seems to exist (Figure 4). Garcinia cambogia was the main
source of HCA in most studies, with Garcinia atroviridis
being the source of HCA in one included study [2]. None of
the trials used Garcinia indica as an intervention. It is unclear
if the strain of Garcinia species influences the bioavailability
of HCA. Furthermore HCA is also reported to be found in
Hibiscus subdariffa[8], and none of the studies included in
this review used HCA extracted from this plant species. The
duration of the studies included in the review also differed,
witharangeof2to12weeks,andmodeof8weeks.This
is probably too short a time to assess the effects of HCA on
body weight.
There was some variation in the design of the RCTs
included in the review. All of the studies included had
parallel-study designs except two which were crossover trials
[26,27]. Four included RCTs comprised three intervention
groups [6,26,27,29]. None of the included studies indicated
whether or not outcome assessors were blinded, and seven
studies did not specify the source of funding [2,4,6,24,28,
29,31]. The failure of study investigators to adhere strictly
to the CONSORT guidelines [10,11] may have contributed
to the variation in methodology (and heterogeneity) of the
trials included in the review.
Most (7/12) RCTs reported adverse events, with
headache, nausea, upper respiratory, and gastrointestinal
tract symptoms being the most frequent ones. In most of the
trials, there were no significant differences in adverse events
between HCA and placebo. This seems to corroborate the
report in another article [34] which suggested that HCA is
safe for human consumption. A few of the studies reported a
positive effect of HCA on the blood lipid profile [6,24,29–
31], while one did not find any significant difference between
HCA and placebo on this blood parameter [2]. However,
given the short duration of the studies involving the use
of HCA, it is unclear how safe this dietary supplement is
on the intermediate and long term. In 2009, the Food and
Drug Administration (FDA) warned consumers about the
potential for serious adverse effects associated with the
consumption of hydroxycut, a popular HCA-containing
slimming pill. This resulted in the withdrawal of this
supplement from the market [35].
All of the studies included in this review except two
[26,27] incorporated some form of dietary control into their
trials, with participants in one study receiving high fibre diets
[25]. The daily caloric intake for participants in the trials
included in this review ranged from as low as 1,000 kcal
[2,30], to as high as 3,009 kcal [27]. Half the number of
studies in this review did not institute any form of exercise.
The extent to which the variation in these lifestyle adjustment
factors could have influenced study results is uncertain. Two
studies [28,31] reported a significant reduction in appetite
in the HCA group (P<.001), but not with placebo. Three
other studies did not find any significant difference between
HCA and placebo groups in terms of satiety effect [5,26,27].
All of the studies described their participants as over-
weight, obese, or both. However, in one RCT [2], the
definition of the participants as obese individuals is ques-
tionable, because they had a BMI between 25–30 kg/m2.
Based on the World Health Organisation definition [36], a
BMI between 25–29 kg/m2is considered overweight, while a
BMI ≥30 kg/m2is termed obese.
This systematic review has several limitations. Though
our search strategy involved both electronic and non-
electronic studies, we may not have identified all the available
trials involving the use of HCA as a weight loss supplement.
Furthermore, the methodological quality of most of the
studies identified from our searches is poor, and most studies
are of short duration. These factors prevent us from drawing
firm conclusions about the effects of HCA on body weight.
5. Conclusion
The evidence from RCTs suggests that Garcinia extracts/HCA
generate weight loss on the short term. However, the
magnitudeofthiseffect is small, is no longer statistically
significant when only rigorous RCTs are considered, and its
clinical relevance seems questionable. Future trials should be
more rigorous, longer in duration, and better reported.
Conflict of Interests
I. Onakpoya was funded by a grant from GlaxoSmithKline.
The funder had no role in the preparation of the paper. S. K.
Hung,R.Perry,B.WiderandE.Ernestdeclarenopotential
competing interests.
Acknowledgment
The authors would like to thank Ms. Shoko Masuyama for
help with translating Japanese articles.

8Journal of Obesity
References
[1] T. Farhat, R. J. Iannotti, and B. G. Simons-Morton, “Over-
weight, obesity, youth and health-risk behaviours,” American
Journal of Preventive Medicine, vol. 38, no. 3, pp. 258–267,
2010.
[2] C. Roongpisuthipong, R. Kantawan, and W. Roongpisuth-
ipong, “Reduction of adipose tissue and body weight: effect of
water soluble calcium hydroxycitrate in Garcinia atroviridis on
the short term treatment of obese women in Thailand,” Asia
Pacific Journal of Clinical Nutrition, vol. 16, no. 1, pp. 25–29,
2007.
[3] B. W. Downs, M. Bagchi, G. V. Subbaraju, M. A. Shara, H.
G. Preuss, and D. Bagchi, “Bioefficacy of a novel calcium-
potassium salt of (-)-hydroxycitric acid,” Mutation Research,
vol. 579, no. 1-2, pp. 149–162, 2005.
[4] K. Hayamizu, Y. Ishii, I. Kaneko et al., “Effects of Garcinia
cambogia (Hydroxycitric Acid) on visceral fat accumulation: a
double-blind, randomized, placebo-controlled trial,” Current
Therapeutic Research, vol. 64, no. 8, pp. 551–567, 2003.
[5] R. D. Mattes and L. Bormann, “Effects of (-)-hydroxycitric
acid on appetitive variables,” Physiology and Behavior, vol. 71,
no. 1-2, pp. 87–94, 2000.
[6] H. G. Preuss, D. Bagchi, M. Bagchi, C. V. S. Rao, S.
Satyanarayana, and D. K. Dey, “Efficacy of a novel, natural
extract of (-)-hydroxycitric acid (HCA-SX) and a combination
of HCA-SX, niacin-bound chromium and Gymnema sylvestre
extract in weight management in human volunteers: a pilot
study,” Nutrition Research, vol. 24, no. 1, pp. 45–58, 2004.
[7] E. Toromanyan, G. Aslanyan, E. Amroyan, E. Gabrielyan,
and A. Panossian, “Efficacy of Slim339in reducing body
weight of overweight and obese human subjects,” Phytotherapy
Research, vol. 21, no. 12, pp. 1177–1181, 2007.
[8] T. Yamada, H. Hida, and Y. Yamada, “Chemistry, physiological
properties, and microbial production of hydroxycitric acid,”
Applied Microbiology and Biotechnology, vol. 75, no. 5, pp. 977–
982, 2007.
[9] M. Leonhardt, B. Hrupka, and W. Langhans, “Effect of
hydroxycitrate on food intake and body weight regain after
a period of restrictive feeding in male rats,” Physiology and
Behavior, vol. 74, no. 1-2, pp. 191–196, 2001.
[10] D. Moher, K. F. Schulz, D. G. Altman, and L. Lepage,
“The CONSORT statement: revised recommendations for
improving the quality of reports of parallel-group randomised
trials,” Lancet, vol. 357, no. 9263, pp. 1191–1194, 2001.
[11] D.G.Altman,K.F.Schulz,D.Moheretal.,“TherevisedCON-
SORT statement for reporting randomized trials: explanation
and elaboration,” Annals of Internal Medicine, vol. 134, no. 8,
pp. 663–694, 2001.
[12] A. R. Jadad, R. A. Moore, D. Carroll et al., “Assessing the
quality of reports of randomized clinical trials: is blinding
necessary?” Controlled Clinical Trials, vol. 17, no. 1, pp. 1–12,
1996.
[13] Review Manager (RevMan), [Computer Program]. Version
5.0. Copenhagen: The Nordic Cochrane Centre, The Cochrane
Collaboration, 2008.
[14] A. A. Conte, “A non-prescription alternative in weight reduc-
tion therapy,” American Journal of Bariatric Medicine Summer,
pp. 17–19, 1993.
[15] M. Girola, M. De Bernardi, and S. Contos, “Dose effect in
lipid-lowering activity of a new dietary integrator (Chitosan,
Garcinia cambogia extract, and Chrome),” Acta Toxicolog ica e t
Therapeutica, vol. 17, pp. 25–40, 1996.
[16] D. Q. Rothacker and B. E. Waitman, “Effectiveness of a
Garcinia cambogia and natural caffeine combination in weight
loss: a double-blind placebo-controlled pilot study,” Interna-
tional Journal of Obesity, vol. 12, supplement 2, p. 53, 1997.
[17] C. A. R. Vasques, S. Rossetto, G. Halmenschlager et al.,
“Evaluation of the pharmacotherapeutic efficacy of Garcinia
cambogia plus amorphophallus konjac for the treatment of
obesity,” Phytotherapy Research, vol. 22, no. 9, pp. 1135–1140,
2008.
[18] Y. Yonei, Y. Takahashi, S. Hibino, M. Watanabe, and T.
Yoshioka, “Effects on the human body of a dietary supplement
containing L-carnitine and Garcinia cambogia extract: a study
using double-blind tests,” Journal of Clinical Biochemistry and
Nutrition, vol. 42, no. 2, pp. 89–103, 2008.
[19] V. Badmaev and M. Majeed, “Open field, physician controlled,
clinical evaluation of botanical weight loss formula Citrin,”
in Proceedings of the Nutracon: Nutraceuticals, Dietary Supple-
ments and Functional Foods, Las Vegas, Nev, USA, July 1995.
[20] M.S.Westerterp-PlantengaandE.M.R.Kovacs,“Theeffect of
(-)-hydroxycitrate on energy intake and satiety in overweight
humans,” International Journal of Obesity,vol.26,no.6,pp.
870–872, 2002.
[21] A. A. Conte, “The effects of (-)-hydroxycitrate and chromium
(GTF) on obesity,” Journal of American College of Nutrition,
vol. 13, p. 535, 1994.
[22] H. G. Preuss, R. I. Garis, J. D. Bramble et al., “Efficacy of
a novel calcium/potassium salt of (-)-hydroxycitric acid in
weight control,” International Journal of Clinical Pharmacology
Research, vol. 25, no. 3, pp. 133–144, 2005.
[23] E. M. R. Kovacs and M. S. Westerterp-Plantenga, “Effects of
(-)-hydroxycitrate on net fat synthesis as de novo lipogenesis,”
Physiology and Behavior, vol. 88, no. 4-5, pp. 371–381, 2006.
[24] K. Hayamizu, Y. Ishii, and I. Kaneko, “Effects of long-term
administration of Garcinia cambogia extract on visceral fat
accummulation in humans: a placebo-controlled double blind
trial,” Journal of Oleo Science, vol. 50, no. 10, pp. 43–50, 2001.
[25] S. B. Heymsfield, D. B. Allison, J. R. Vasselli, A. Pietrobelli, D.
Greenfield, and C. Nunez, “Garcinia cambogia (hydroxycitric
acid) as a potential antiobesity agent: a randomized controlled
trial,” Journal of the American Medical Association, vol. 280, no.
18, pp. 1596–1600, 1998.
[26] E. M. R. Kovacs, M. S. Westerterp-Plantenga, M. De Vries,
F. Brouns, and W. H. M. Saris, “Effects of 2-week ingestion
of (-)-hydroxycitrate and (-)-hydroxycitrate combined with
medium-chain triglycerides on satiety and food intake,”
Physiology and Behavior, vol. 74, no. 4-5, pp. 543–549, 2001.
[27] E. M. R. Kovacs, M. S. Westerterp-Plantenga, and W. H. M.
Saris, “The effects of 2-week ingestion of (-)-hydroxycitrate
and (-)-hydroxycitrate combined with medium-chain triglyc-
erides on satiety, fat oxidation, energy expenditure and body
weight,” International Journal of Obesity,vol.25,no.7,pp.
1087–1094, 2001.
[28] H. G. Preuss, D. Bagchi, C. V. S. Rao, S. Satyanarayana, and M.
Bagchi, “Effect of hydroxycitric acid on weight loss, body mass
index and plasma leptin levels in human subjects,” FASE B
Journal, vol. 16, no. 5, p. A1020, 2002.
[29] H. G. Preuss, D. Bagchi, M. Bagchi, C. V. S. Rao, D. K. Dey,
and S. Satyanarayana, “Effects of a natural extract of (-)-
hydroxycitric acid (HCA-SX) and a combination of HCA-SX
plus niacin-bound chromium and Gymnema sylvestre extract
on weight loss,” Diabetes, Obesity and Metabolism, vol. 6, no.
3, pp. 171–180, 2004.

Journal of Obesity 9
[30] R. Roman Ramos, J. Flores Saenz, and M. C. F. Alarcon Aguilar
en, “Control of obesity with Garcinia cambogia extract,”
Investigacion Medica Internacional, vol. 22, no. 3, pp. 97–100,
1996.
[31] E. Thom, “Hydroxycitrate (HCA) in the treatment of obesity,”
American Journal of Clinical Nutrition,vol.20,no.l4,p.48,
1996.
[32] M. H. Pittler and E. Ernst, “Dietary supplements for body-
weight reduction: a systematic review,” American Journal of
Clinical Nutrition, vol. 79, no. 4, pp. 529–536, 2004.
[33] D. Rucker, R. Padwal, S. K. Li, C. Curioni, and D. C. W.
Lau, “Long term pharmacotherapy for obesity and overweight:
updated meta-analysis,” British Medical Journal, vol. 335, no.
7631, pp. 1194–1199, 2007.
[34] M. G. Soni, G. A. Burdock, H. G. Preuss, S. J. Stohs, S. E.
Ohia, and D. Bagchi, “Safety assessment of (-)-hydroxycitric
acid and Super CitriMax, a novel calcium/potassium salt,”
Food and Chemical Toxicology, vol. 42, no. 9, pp. 1513–1529,
2004.
[35] “How Worrisome is the Hydroxycut Recall for the Diet
Supplement Industry?” to appear in Nutrition Business Jour-
nal, 2009, http://www.nutritionbusinessjournal.com/supple-
ments/news/0505.
[36] World Health Organisation, “Obesity and overweight,” Fact
sheet no. 311, September 2006, http://www.who.int/media-
centre/factsheets/fs311/en/index.html.