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The Efficacy of Irvingia Gabonensis Supplementation in the Management of Overweight and Obesity: A Systematic Review of Randomized Controlled Trials

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ABSTRACT The aim of this systematic review was to evaluate the evidence from randomized controlled trials (RCTs) involving the use of the African Bush Mango, Irvingia gabonensis for body weight reduction in obese and overweight individuals. Electronic and nonelectronic searches were conducted to identify relevant RCTs. The bibliographies of located articles were also searched. No age, gender, or language restrictions were imposed. The reporting quality of identified RCTs was assessed using a methodological checklist adapted from the Consolidated Standard of Reporting Trials Statement and Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Two reviewers independently determined eligibility and assessed the reporting quality of included studies. Three RCTs were identified, and all were included. The RCTs all had flaws in the reporting of their methodology. All RCTs reported statistically significant reductions in body weight and waist circumference favoring I. gabonensis over placebo. The results from the RCTs also suggest positive effects of I. gabonensis supplementation on the blood lipid profile. Adverse events included headache and sleep difficulty. Due to the paucity and poor reporting quality of the RCTs, the effect of I. gabonensis on body weight and related parameters are unproven. Therefore, I. gabonensis cannot be recommended as a weight loss aid. Future research in this area should be more rigorous and better reported.
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Journal of Dietary Supplements, 10(1):29–38, 2013
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2013 by Informa Healthcare USA, Inc.
Available online at www.informahealthcare.com/jds
DOI: 10.3109/19390211.2012.760508
The Efcacy of Irvingia Gabonensis
Supplementation in the Management of
Overweight and Obesity: A Systematic Review of
Randomized Controlled Trials
Igho Onakpoya, MD, Lucy Davies, PhD, Paul Posadzki, PhD,
& Edzard Ernst,
MD, PhD
Complementary Medicine, Peninsula Medical School, University of Exeter,
United Kingdom
ABSTRACT. The aim of this systematic review was to evaluate the evidence from ran-
domized controlled trials (RCTs) involving the use of the African Bush Mango, Irvingia
gabonensis for body weight reduction in obese and overweight individuals. Electronic
and nonelectronic searches were conducted to identify relevant RCTs. The bibliogra-
phies of located articles were also searched. No age, gender, or language restrictions
were imposed. The reporting quality of identied RCTs was assessed using a method-
ological checklist adapted from the Consolidated Standard of Reporting Trials State-
ment and Preferred Reporting Items for Systematic Reviews and Meta-analyses guide-
lines. Two reviewers independently determined eligibility and assessed the reporting
quality of included studies. Three RCTs were identied, and all were included. The
RCTs all had aws in the reporting of their methodology. All RCTs reported statis-
tically signicant reductions in body weight and waist circumference favoring I. gabo-
nensis over placebo. The results from the RCTs also suggest positive effects of I. gabo-
nensis supplementation on the blood lipid prole. Adverse events included headache
and sleep difculty. Due to the paucity and poor reporting quality of the RCTs, the ef-
fect of I. gabonensis on body weight and related parameters are unproven. Therefore,
I. gabonensis cannot be recommended as a weight loss aid. Future research in this area
should be more rigorous and better reported.
KEYWORDS. Irvingia gabonensis, obesity, overweight, randomized controlled trial,
systematic review
INTRODUCTION
The prevalence of adult obesity has doubled over the last three decades
(Finucane, Stevens, Cowan, Danaei, Lin, & Paciorek, 2011), and hundreds of weight
loss supplements are currently available. However, the efcacy of most of these
Address correspondence to: Igho Onakpoya, MD, Complementary Medicine, Peninsula Medical School, Uni-
versity of Exeter, United Kingdom. (Email: igho.onakpoya@pcmd.ac.uk)
(Received 22 June 2012; revised 18 September 2012; accepted 17 December 2012)
29
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30 Onakpoya et al.
supplements is not established. One such supplement is the seed extract of the
African bush mango, Irvingia gabonensis.
I. gabonensis is an herb native to West Africa, and belongs to the Irvingiaceae
family (White & Albernethy, 1996). The eshy fruity part of the African mango is
usually consumed, while the seed is also used in various types of dishes (Okafor
& Okolo, 1996). I. gabonensis reportedly has high ber content, and its seeds con-
tain glycoproteins which can inhibit hydrolysis (Okafor & Okolo, 1996). I. gabo-
nensis has been hypothesized to possess antidiabetic properties due to its ability
to decrease fasting blood sugar levels (Adamson, Okafor, & Abu-Bakare, 1990),
and has also been demonstrated to inhibit adipogenesis in vitro (Oben, Ngondi,
& Blum, 2008). I. gabonensis also reportedly possesses anticholesterol properties
(Tchoundjeu, & Atangana, 2007; Ross, 2011).
I. gabonensis has become popular as a weight loss supplement, and has been
reported in the media as the new “obesity killer” (Benzinga.com, 2011). A recent
review article concluded that I. gabonensis has shown potential benet in causing
weight loss (Egras, Hamilton, Lenz, & Monaghan, 2011). Controlled trials involving
the use of I. gabonensis for body weight reduction are now being conducted, and
results from such trials have recently become available.
The objective of this systematic review is to critically evaluate the evidence for
or against the efcacy of I. gabonensis supplementation in overweight and obese
humans.
METHODS
We conducted electronic searches in the following databases: Medline, Embase,
Amed, and The Cochrane Library. Each database was searched from inception to
April, 2012. The search terms used included antiobesity agent, overweight, obe-
sity, weight loss, slimming, body weight, body fat, adiposity, BMI, I. gabonensis,
bush mango, wild mango, African mango, bread tree, dika nut, and derivatives of
these (a comprehensive search strategy has been included as a supplement to this
manuscript as Figure 1S). We also searched the internet for relevant conference
proceedings and hand searched relevant medical journals, and our own les. The
bibliographies of all located articles were also searched. No age, gender, or lan-
guage restrictions were imposed.
Only randomized, double-blind, placebo-controlled trials (RCTs) were included
in this review. To be considered for inclusion, RCTs had to test the efcacy of
orally administered I. gabonensis-containing supplement for body weight reduction
in overweight (BMI 25–29.9 kg/m
2
) or obese (BMI 30 kg/m
2
) human volun-
teers (World Health Organisation, 2011). Included studies also had to report body
weight or body composition as an outcome measure. Studies were also included ir-
respective of whether or not they incorporated lifestyle modication into the trial
regimen.
Two reviewers (I. Onakpoya and L. Davies) independently assessed the eligibil-
ity of studies. Data were extracted by two reviewers (I. Onakpoya and L. Davies)
according to patient characteristics, interventions, and results. The methodologi-
cal quality of all included studies was assessed by the use of a quality assessment
checklist adapted from the Consolidated Standard of Reporting Trials Statement
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The Efcacy of Irvingia gabonensis Supplementation 31
Records identified through database
searching
(n = 458)
Screening Included
Eligibility
Idenficaon
Additional records identified
through other sources
(n = 0)
No. of duplicates removed
(n = 27)
Records screened
(n = 431)
Records excluded
(n = 428)
Full-text articles assessed
for eligibility
(n = 3)
Full-text articles excluded,
with reasons
(n = 0)
Studies included in
qualitative synthesis
(n = 3)
Studies included in
quantitative synthesis
(meta-analysis)
(n = 0)
FIGURE 1. Flow chart showing the process for the inclusion and analysis of RCTs. The
Flow Diagram has been adapted from the online version of the PRISMA statement, 2009.
Available from: http://www.prisma-statement.org/statement.htm.
(Schulz, Altman, & Moher, 2010) and the Preferred Reporting Items for System-
atic Reviews and Meta-analyses guidelines (Moher, Liberati, Tetzlaff, & Altman,
2009). Disagreements were resolved through discussion.
RESULTS
Our electronic searches identied 431 nonduplicate citations (Figure 1), out of
which 3 eligible trials (Ngondi, Etoundi, Nyangono, Mdofung, & Oben, 2009;
Ngondi, Oben, & Minka, 2005; Oben, Ngondi, Momo, Agbor, & Sobgui, 2008) were
identied, and subsequently included in the review. These RCTs included a total of
208 participants. Key details of these RCTs are summarized in Tables 1 and 2. Two
RCTs (Ngondi et al., 2009; Oben et al., 2008) were of parallel design, while one
(Ngondi et al., 2005) was cross-over. Participants in all three RCTs were of African
origin.
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TABLE 1. Reporting Characteristics of I. gabonensis RCTs
First Author
Year Country
Main
Outcome (s)
Main Diagnoses
of Study
Participants
Study
Design
Sex
M/F
Randomization
Appropri-
ate?
Allocation
Con-
cealed?
Sample
Size De-
termined?
Groups
Similar at
Baseline?
Outcome
Assessor
Blinded?
Care
Provider
Blinded?
Patients
Blinded?
Attrition
Bias?
ITT
Analy-
sis?
Modied
Lifestyle?
Ngondi 2009
Cameroon
Body weight,
BMI lipid
prole
Healthy over-
weight/obese
subjects
Parallel 62/58 Unclear Unclear Unclear Yes Unclear Unclear Unclear Unclear No Yes
(Ngondi
et al.,
2005)
Cameroon
Body compo-
sition,
body
weight
Healthy over-
weight/obese
subjects
Cross-
over
NR Unclear Unclear Unclear No Unclear Yes Yes Unclear No Yes
(Oben et al.,
2008)
Cameroon
Body compo-
sition,
lipid
prole
Healthy over-
weight/obese
subjects
Parallel 33/39 Unclear Unclear Unclear Yes Unclear Yes Yes Unclear Unclear No
Abbreviation: M/F, males/females; NR, not reported.
32
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TABLE 2. Main Results of I. gabonensis RCTs
First Author
Year
Daily
Dosage and
Formulation
Randomized/
analyzed Age in Years
Baseline Body Weight
(kg)
Treatment
Duration
Main Results on Body
Anthropometry (I.
gabonensis versus Placebo)
Other Metabolic Parameters
(I. gabonensis versus
Placebo) Adverse Events (AE)
Ngondi 2009 150 mg × 2
capsules
120/102 19 to 50 for all
subjects
97.9 ± 9.1 (IG)
96.4 ± 12.3 (PLA)
10 weeks Sig in BW (12.8 versus
0.7 kg);% BF (6.3 versus
2.0%) and WC (16.2
versus 5.3 cm)
Sig in serum leptin levels
(16.0 versus 3.0 ng/ml);
LDL-C (22.4 versus
3.8 mg/dL) and CT (39.8
versus 2.8 mg/dL); CRP
(0.8 versus 0.01 mg/L);
FBG (19.3 versus
4.3 mg/dL) and signicant
adinopectin (19.4 versus
2.8 mg/L).
Headache, sleep
difculty, atulence
(Ngondi
et al.,
2005)
1,050 mg × 3
capsules
40/40 19 to 55 for all
subjects
105.1 ± 16.98 (IG)
79.43 ± 9.83 (PLA)
4 weeks Sig in BW (4.1 versus
0.1 kg),
2
WC (6.2 versus
+1.5 cm) and HC (4.5
versus 0.7 cm). No sig diff
in % BF (0.8 versus
0.3%)
Sig in systolic BP (3.6
versus 1.2mmHg). Sig in
HDL-C in IG
(28.7 mg/dL). Sig in CT
(84.3 mg/dL) and LDL-C
(55.3 mg/dL), CT/HDL
ratio (2.1), and FBG
(1.2 mmol/L) levels in IG
group.
Not reported
1
Oben et al.,
2008
250 mg × 2
capsule
(IG-CQ)
72/72 21 to 44 for all
subjects
99.79 ± 13.5 (IG)
98.05 ± 12.3 (PLA)
10 weeks Sig in BW (11.9 versus
2.1 kg), % BF (20.1 versus
4.0%) and WC (21.9 versus
1.0 cm).
Sig in LDL-C (25.8 versus
3.0 mg/dL), CT (44.8
versus 2.2 mg/dL), and
FBG (27.6 versus
2.1 mg/dL).
Headache, sleep
difculty, gas
Abbreviations: IG, Irvingia gabonensis; IG-CQ, Irvingia gabonensis-Cissus quadrangularis combination; PLA, placebo; BW, body weight; % BF, percentage body fat; WC, waist circumference;
HC, hip circumference; CRP, C-reactive protein; FBG, fasting blood glucose; LDL-C, low-density lipoprotein cholesterol; CT, total cholesterol; HDL-C, high-density lipoprotein cholesterol.
1
Study had three groups of participants; analysis was confined to the IG-CQ and PLA groups.
2
Decrease in waist circumference in I. gabonensis group and an increase in waist circumference in placebo group.
33
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34 Onakpoya et al.
All RCTs included in the review had aws in the reporting of their methodol-
ogy (Table 1). None of the RCTs reported appropriate randomization or allocation
concealment procedures in their trial, and no RCT reported outcome assessors as
being blinded. Two RCTs (Ngondi et al., 2005; Oben et al., 2008) reported ade-
quate blinding of both care providers and study participants, while the participants
in one RCT (Ngondi et al., 2005) did not have similar characteristics at baseline.
No RCT reported carrying out a sample size calculation, and none performed an
intention-to-treat (ITT) analysis.
Two RCTs (Ngondi et al., 2009; Oben et al., 2008) lasted 10 weeks each, while
the third RCT (Ngondi et al., 2005) lasted 4 weeks. Although one RCT (Ngondi
et al., 2005) was reported as cross-over, the investigators did not report whether
or not there was a wash-out period. The daily dosages of I. gabonensis differed
amongst the three RCTs. This ranged from about 200 mg (Oben et al., 2008) to
about 3,150 mg (Ngondi et al., 2005).
Two RCTs (Ngondi et al., 2009; Oben et al., 2008) reported using a stadiometer
for body weight measurement, while the scale used in the third RCT (Ngondi et al.,
2005) was not specied. All the RCTs estimated body fat composition with bioelec-
tric impedance. All the RCTs also measured waist and hip circumferences by using
a nonstretchable plastic tape on the narrowest and widest part of the trunk.
Two RCTs (Ngondi et al., 2009; Ngondi et al., 2005) incorporated lifestyle mod-
ication into their trial regimen. While participants in one of these RCTs (Ngondi
et al., 2005) had a restricted daily caloric intake (1,800 kcal), subjects in the other
RCT (Ngondi et al., 2009) had daily caloric intakes ranging from 2,580 to 3,341
kcal. Two RCTs (Ngondi et al., 2009; Ngondi et al., 2005) had I. gabonensis as sole
intervention, while participants in the intervention group in the third RCT (Oben
et al., 2008) had I. gabonensis in combination with another herbal supplement (Cis-
sus quadrangularis). Generally, subjects in all RCTs were allowed to continue with
their normal level of physical activity.
Because of the small number and poor reporting quality of the included RCTs,
a meta-analysis was deemed inappropriate. The main results of the three RCTs are
discussed here. All RCTs (Ngondi et al., 2009; Ngondi et al., 2005; Oben et al.,
2008) reported statistically signicant reductions in body weight in the I. gabonen-
sis group compared with placebo (12.8 versus 0.7 kg, p < .01; 4.1 versus 0.1 kg, p <
.01; and 11.9 versus 2.1 kg, p < .0001, respectively). Using a 10-week time point,
the weight loss in each of these RCTs translate to >5% from baseline, and sug-
gest clinical signicance (Lau, Douketis, Morrison, Hramiak, Sharma, & Ur, 2006).
Two RCTs (Ngondi et al., 2009; Oben et al., 2008) reported signicant reductions
in percentage body fat in the I. gabonensis group compared with placebo (6.3%
versus 2.0% and 20.1 versus 4.0%, respectively, p < .05 in both studies), while one
study (Ngondi et al., 2005) reported no signicant changes in both I. gabonensis
and placebo groups (0.8% versus 0.3%).
All RCTs (Ngondi et al., 2009; Ngondi et al., 2005; Oben et al., 2008) reported
statistically signicant changes in waist circumference in the I. gabonensis group
compared with placebo (16.2 versus 5.3 cm, p < .05; 6.2 versus +5.5 cm, p <
.01; and 21.9 versus 1.0 cm, p < .0001, respectively), and one RCT (Ngondi et al.,
2005) also noted a signicant reduction in hip circumference in the I. gabonensis
group compared with placebo (4.5 versus 0.7 cm, p < .0001).
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The Efcacy of Irvingia gabonensis Supplementation 35
Two RCTs (Ngondi et al., 2009; Oben et al., 2008) reported statistically sig-
nicant reductions in total cholesterol in the I. gabonensis group compared with
placebo (39.8 versus 2.8 mg/dL, p < .05; and 68.4 versus 7.8 mg/dL, p < .001,
respectively). The third RCT (Ngondi et al., 2005) noted a signicant decrease
(84.3 mg/dL, p < .05) in total cholesterol in the I. gabonensis group without a sig-
nicant change in the placebo group. Two RCTs (Ngondi et al., 2009; Oben et al.,
2008) reported signicant reductions in low-density lipoprotein (LDL) cholesterol
in the I. gabonensis group compared with placebo (22.4 versus 3.8 mg/dL, p < .01;
and 25.8 versus 3.0 mg/dL, p < .001), while the third RCT (Ngondi et al., 2005) de-
scribed a signicant decrease in LDL cholesterol in the I. gabonensis group (46%;
p < .05) without mentioning the result of between-group differences. One RCT
(Ngondi et al., 2005) reported a signicant increase in high-density lipoprotein
(HDL) cholesterol level in the I. gabonensis group (47%; p < .05), and a signi-
cant decrease in total cholesterol/HDL ratio in the I. gabonensis group (2.1, p <
.05) without a signicant change in the placebo group for these variables.
Two RCTs (Ngondi et al., 2009; Oben et al., 2008) observed statistically signi-
cant reductions in fasting blood glucose levels in the I. gabonensis group compared
with placebo (19.3 versus 4.3 mg/dL, p < .05; and 27.6 versus 2.1 mg/dL, p < .001,
respectively), while the third RCT (Ngondi et al., 2005) reported a signicant de-
crease in fasting blood glucose levels in the I. gabonensis group (32.4%; p < .05)
with a corresponding increase in the placebo group (8.3%); there was no report
on between-group differences. One RCT (Ngondi et al., 2009) noted signicant de-
creases in serum leptin levels in the I. gabonensis group compared with placebo
(16.0 versus 3.0 ng/ml, p < .01), and corresponding signicant increase in serum
adinopectin (19.4 versus 2.8 ng/ml, p < .05). One RCT (Ngondi et al., 2005) demon-
strated a statistically signicant reduction in systolic blood pressure in the I. gabo-
nensis group compared with placebo (3.6 versus 1.2 mmHg, p < .001).
Two RCTs (Ngondi et al., 2009; Oben et al., 2008) reported adverse events
(Table 2). These included headache, sleep difculties, and atulence. In general,
the authors noted that there were no signicant differences in adverse events be-
tween the I. gabonensis and placebo groups. Adverse event reports were lacking in
one RCT (Ngondi et al., 2005). None of the RCTs provided information regard-
ing the compliance of study participants during the intervention period. Eighteen
drop-outs were reported in one RCT (Ngondi et al., 2009); the other RCTs did not
mention information on drop-outs/attrition.
Two RCTs (Ngondi et al., 2009; Oben et al., 2008) reported their sources of fund-
ing. While one of these (Ngondi et al., 2009) was partially funded by the govern-
ment, the other RCT (Oben et al., 2008) was entirely funded by industry.
DISCUSSION
The results of the RCTs included in this review suggest that I. gabonensis supple-
mentation generates statistically signicant reductions in body weight and waist cir-
cumference, compared with placebo. The ndings also indicate that I. gabonensis
supplementation causes markedly positive effects on the blood lipid prole when
compared with placebo. The results of these RCTs should be interpreted with cau-
tion because of deciencies in the reporting of methodology in the included RCTs.
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36 Onakpoya et al.
I. gabonensis has been reported to have benecial effects on body composition
largely via its action on serum leptin. Leptin regulates energy intake and expendi-
ture by acting as an adiposity signal (Williams, Scott, & Elmquist, 2009), and hu-
man studies have demonstrated that serum leptin levels are positively correlated
with body weight and percentage body fat (Iwamoto, Takeda, Sato, & Matsumoto,
2011). Research in humans has also shown that while serum leptin correlates with
percentage body fat in white populations, same nding was not observed in blacks
(Ruhl et al., 2004). I. gabonensis has been purported to decrease the levels of serum
leptin (Oben et al., 2008; Ngondi et al., 2009), thereby reducing adipose tissue lev-
els. Even though one RCT (Ngondi et al., 2009) reported signicant reductions in
serum leptin due to I. gabonensis supplementation, the hypotheses linking I. gabo-
nensis with reduced serum leptin levels have largely been based on animal studies.
Whether blacks are genetically susceptible to the effects of I. gabonensis on serum
leptin is not clear, and requires further investigation.
A recent animal study has shown that I. gabonensis binds to bile acids in the gut,
thereby causing its fecal elimination (Nangue, Womeni, Mbiapo, Fanni, & Michel,
2011). This study reported signicant increases in HDL cholesterol compared with
placebo, but no signicant differences were observed for LDL cholesterol. The nd-
ings from one of the RCTs (Ngondi et al., 2005) corroborate the result of the animal
study regarding HDL cholesterol. However, in contrast to the ndings from this
study, the RCTs in this review reported signicant effects of I. gabonensis on LDL
cholesterol. Investigations into the mechanism by which this effect was achieved
seem warranted; similarly, it would be interesting to determine whether this mech-
anism differs from that observed in animals.
One RCT (Ngondi et al., 2005) reported a signicant decrease in systolic blood
pressure in the I. gabonensis-supplemented group. However, the therapeutic value
of this decrease seems doubtful. The subjects in the study all had normal systolic
blood pressures (136 mmHg), and a reduction of 3.6 mmHg does not necessarily
indicate clinical relevance. There have been no trials investigating the effects of I.
gabonensis on blood pressure, and no mechanism is known.
Adjustments in lifestyles, such as behavior, diet, and physical activity, are an
important aspect in the management of overweight and obesity (Avenell, Sattar,
& Lean, 2007; Wadden, Butryn, & Wilson, 2007). There were wide discrepancies
in the daily caloric intakes of participants in the two RCTs (Ngondi et al., 2009;
Ngondi et al., 2005) which reported this variable. Though participants in all the
RCTs were asked to continue with their normal level of physical activity during the
intervention duration, the levels of this activity was not specied. It is unclear the
extent to which these variations in lifestyle adjustment inuenced the outcome of
study results. It is also quite puzzling how participants in one RCT (Ngondi et al.,
2009) though having very high daily caloric intakes, lost a lot of weight during the
trial.
The wide variation in average daily dosages across the three RCTs included in
this review is concerning, as the large differences make it difcult to ascertain the
minimum effective dose of I. gabonensis required to cause a weight loss. Participants
in one RCT (Ngondi et al., 2005) received >10 times the daily dosages of I. gabonen-
sis compared with the subjects in the other two RCTs (Ngondi et al., 2009; Oben
et al., 2008), but the weight loss in all the RCTs was comparable (approximately
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The Efcacy of Irvingia gabonensis Supplementation 37
4 kg weekly). Similar ndings were also reported for fasting blood sugar and blood
lipid prole variables across the studies.
The variety in study methodology (in relation to both reporting quality and de-
sign), small sample sizes, variation in dosages, and the generally short duration of
the intervention period limit the extent to which efcacy or otherwise can be in-
ferred, and lack of detailed reporting creates doubts regarding the internal and ex-
ternal validity of the included studies (Schulz et al., 2010; Moher et al., 2009; Wittes,
2002). The demographic characteristics of the study participants also conne the
ndings of the results to individuals of black African descent. Furthermore, all the
RCTs have been conducted by a small group of investigators from the same geo-
graphical area, and published in the same journal. Larger and more independent
trials, which also involve volunteers from other racial backgrounds, are necessary
to allow for a broader and more objective evaluation of the effects of I. gabonensis.
Though the RCTs did not report any signicant differences in adverse events
between the I. gabonensis and placebo groups, this does not conclusively imply that
I. gabonensis supplementation is entirely risk free. Future trials should be longer,
and large postmarketing surveillance studies would be valuable for determining the
safety of I. gabonensis (Ioannidis, Evans, & Gøtzsche, 2004).
This systematic review has several limitations. Though we searched both elec-
tronic and nonelectronic sources, we may not have identied all RCTs involving
the use of I. gabonensis, especially unpublished trials, if any. Furthermore, the poor
quality of RCTs prevents us from making rm conclusions about the effects of I.
gabonensis on body composition.
CONCLUSION
The results from available RCTs suggest that I. gabonensis supplementation causes
signicant reductions in body weight and waist circumference. However, the report-
ing of the methodology of the RCTs is poor and all the trials are of short duration.
Until good quality trials demonstrating its efcacy are available, I. gabonensis can-
not be recommended as a weight loss aid. Future trials of this supplement should
be more rigorous and better reported.
Declaration of interest: I. Onakpoya was funded by a grant from GlaxoSmithk-
line.
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... Functionality through randomized controlled trials (RCTs) in normal healthy and individuals with disease throws light on the use of plant extracts for specific purposes. Studies by Onakpoya, Davies, Posadzki, and Ernst (2013) and Lee, Chung, Fu, Choi, and Lee (2020) focused on (1) healthy individuals (less than 20% had cardiovascular disease/diabetes/people who were obese); (2) oral intake of IGOB131, a proprietary patented form of Irvingia gabonensis seed extract, or any other preparation of I. gabonensis seed extract; (3) outcomes related to weight (body weight, body fat, and waist circumference), cardiovascular biomarkers (high-density lipoproteins, low-density lipoproteins, total cholesterol, triglycerides, and blood pressure); and (4) parallel or crossover RCTs. RCTs of I. gabonensis seed extract supplementation on anthropometric measures and cardiovascular biomarkers were identified from 4 databases by . ...
... Further, high-quality RCTs are needed to determine the effectiveness of I. gabonensis seed extract supplement on weight-related health outcomes. A 2013 systematic review identified only 3 RCTs and concluded that I. gabonensis cannot be recommended for weight loss (Onakpoya et al., 2013). Critchley, Zhang, Suthisisang, Chan, and Tomlinson (2000) suggested that the controls should be carefully chosen such that they closely match with the intervention group as well as standardized for factors such as color, odor, duration, and frequency of intake. ...
Chapter
Plant extracts contain a varied range of chemicals such as terpenoids, phenolic compounds, alkaloids, glucosinolates, and various organic acids. These chemicals are responsible for their unique nature and perceived biological activity of plant extracts. Owing to the wide acclaimed biological activities of plant extracts, they have been used as natural ingredients and have received significant renewed interest recently. Several plant extracts have been used as commercial preservatives in food because of their green image. The current chapter discusses various chemicals present in plant extracts and emphasizes the structure activity relationship of these chemicals.
... The fat contained in Irvingia gabonensis seeds did not influence the body weight of rats or the weight of their organs, although in males it reduced the weight of the liver (Nangue et al., 2011). Numerous studies confirm the ability of Irvingia gabonensis to facilitated weight reduction and treat obesity in humans (Ngondi et al., 2005, Egras, 2011, Ross, 2011, Onakpoya et al, 2013, Méndez-Del Villar et al., 2018. However, the shortcomings in the methodology of these tests cast doubt on the reliability of their results (Egras, 2011). ...
... When applying Irvingia gabonensis, adverse side-effects such as headaches and sleep disorders were determined (Onakpoya et al, 2013). No toxic effects of Irvingia, even at large doses, were found (Kothari et al., 2012). ...
... First, a clear distinction between I. gabonensis and I. wombolu with comparative study are not often undertaken, because the two taxa are morphologically similar [40,67,90,91,92,93,94] and misidentification is suspected in many studies. For example, a sour taste appreciated in African diets [95], was mentioned for the fruit pulp of I. wombolu [34,96] and even used to distinguish I. wombolu from the sweet-tasting I. gabonensis [97], while such a taste has never been perceived by consumers. Thus, botanical misidentification is a serious issue to be addressed in future research, since knowledge of the correct botanical and taxonomic position of plants is essential for a proper understanding of their ethnobotany, medical use, and conservation [98]. ...
... Most of these studies were systematically reviewed by Onakpoya et al., who reported that administration of 200-3150 mg/ day Irvingia gabonensis extract for 4-10 weeks could lead to statistically and clinically significant weight loss and decreased waist circumference compared to a placebo group. Side effects of the extract included headache and sleep difficulty [74]. Irvingia gabonensis emerged from these studies as a useful adjuvant dietary supplement in weight reduction management. ...
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Obesity and associated complications including diabetes, cardiometabolic dysfunction, disability, malignancy and premature mortality are considered epidemic. Research on obesity is therefore of worldwide importance. The development of obesity is a multifactorial phenomenon with contributions from biological, behavioral, genetic and environmental factors. Obesity and its associated issues require various lifestyle modifications and treatment options such medication, exercise, diet, surgery, pharmacological therapy and dietary supplements. Dietary supplements are considered an attractive alternative to traditional therapy due to their low toxicity profile and their accessibility to the general population. Dietary supplements may include one or more dietary ingredients. In this narrative review, we analyze the effects on obesity and obesity-related issues of various natural components. For example, there are a myriad of supplements that have been used as dietary supplements for weight loss such as minerals, vitamins, amino acids, metabolites, herbs, and plant extracts. This narrative review aims to present the benefits and side-effects of several ingredients of dietary supplements for weight loss and treatment of obesity. In particular, the mechanism of action, results of clinical trials, and possible side effects will be presented for the following ingredients: β-Glucans, bitter orange, calcium, vitamin D, chitosan, chromium, cocoa, coleus forskohlii, conjugate linoleic acid, ephedra sinica, fucoxanthin, garcinia cambogia, glucomannan, green coffee, green tea, guar gum, raspberry, hoodia gordonii, irvingia gabonensis, phenylpropylamine, pyruvate, white kidney bean.
... Several plants and their derivatives have brought positive results, mainly in weight reduction, waist circumfer-ence, and suppression of inflammatory pathways. [59][60][61][62][63][64][65][66][67][68] In this context, drugs derived from the Cannabis sativa plant, called phytocannabinoids, have been studied as a treatment option for several pathologies. This plant and its derivatives bring important results in the literature associated with anti-inflammatory, antioxidant, and anticonvulsant effects, among others, 12,69-73 and can be an alternative for the metabolic re-establishment in obesity, given the complexity and incidence of adverse events related to the currently available therapeutic options. ...
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Introduction: Obesity is defined as an excess of accumulation of fat that can be harmful to health. Storage of excess fat in the adipose tissue triggers an inflammatory process, which makes obesity a low-grade chronic inflammatory disease. Obesity is considered a complex and multifactorial disease; hence, no intervention strategy appears to be an ideal treatment for all individuals. Therefore, new therapeutic alternatives are often studied for the treatment of this disease. Currently, herbal medicines are gaining ground in the treatment of obesity and its comorbidities. In this context, much attention is being paid to Cannabis sativa derivatives, and their therapeutic functions are being widely studied, including in treating obesity. Objective: Highlight the pharmacological properties of Δ9-tetrahydrocannabivarin (THCV), Δ9-tetrahydrocannabidinol (THC), and cannabidiol (CBD), the predominant isolated components of Cannabis sativa, as well as its therapeutic potential in the treatment of obesity. Methods: This is a narrative review that shows the existing scientific evidence on the clinical application of Cannabis sativa as a possible treatment for obesity. Data collection was performed in the PubMed electronic database. The following word combinations were used: Cannabis and obesity, Cannabis sativa and obesity, THCV and obesity, THC and obesity, CBD and obesity, and Cannabis sativa and inflammation. Results: Evidence shows that Cannabis sativa derivatives have therapeutic potential due to their anti-inflammatory properties. In addition, people who use cannabis have a lower body mass index than those who do not, making the plant an option to reduce and reverse inflammation and comorbidities in obesity. Conclusion: It is concluded that phytocannabinoids derived from Cannabis sativa have therapeutic potential due to its anti-inflammatory, antioxidant, and neuroprotective properties, making the plant a study option to reduce and reverse inflammation and comorbidities associated with obesity.
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We investigated the effects of Irvingia gabonensis (IG) kernel extract on the metabolism, adiposity indices, redox status, inflammation, adipocytokines, blood leukocyte relative telomere length (RTL), and aerobic capacity of overweight/obese individuals. All participants used the first 12-week phase to monitor body weight. They were then randomly divided into two groups: (1) 300 mg IG or (2) placebo (PLA). Both groups took one tablet per day for 12 weeks. The variables were measured before supplementation and after 3, 6, and 12 weeks of supplementation. RTL and aerobic capacity were measured before and after 12 weeks. Compared with the PLA, the IG increased plasma vitamin C after supplementation at 6 (p < 0.01) and 12 weeks (p < 0.05) and serum adiponectin after 3 weeks (p < 0.05). Compared with before supplementation, plasma malondialdehyde and serum leptin were decreased after 12-week supplementation in both groups and in the PLA, respectively, without any differences between the groups. There were no differences between groups with respect to metabolism, inflammation, RTL, and aerobic capacity after the supplementation. We suggest that 12-week daily IG supplementation improved plasma vitamin C and adiponectin. The findings show the possible mechanism contributing to the effect of IG supplementation on a reduction in obesity-related complications.
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The processing and consumption of mango (Mangifera indica) generate a sizeable amount of kernel waste with enormous and largely unexplored potential, while by-products from njangsa (Ricinodendron heudelotii) seed and bush mango (Irvingia gabonensis) kernel oil extraction are often discarded. This study aims to repurpose these kernels and seed wastes into added/high-value products and evaluate the ethanolic and methanolic extracts of their pressed marcs for polyphenolic content and potential antioxidant activity. The total phenolic content (TPC) and total flavonoid content (TFC) in the marc extracts ranged between 47.87 and 376.0 mg GAE/g and 4.85 and 13.70 mg Rutin/g, respectively. Both mango kernel marc extracts showed higher potent reducing power, ABTṠ⁺ radical and DPPḢ radical scavenging activities with half effective concentration (EC50) values (0.20 - 0.22 mg/mL) comparable to the reference compound; ascorbic acid (0.20 mg/mL). The TPC and TFC of the marc extracts generally strongly correlated with antioxidant activity. Relatively higher contents of xanthophyll and β-carotene were detected in bush mango kernel methanolic extract than in the other extracts. Extraction solvent affected the composition and content of bioactives in pressed marcs of njangsa seed and mango kernel.
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Background This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) is intended to provide clinicians an overview of the body weight effects of concomitant medications (i.e., pharmacotherapies not specifically for the treatment of obesity) and functional foods, as well as adverse side effects of common supplements sometimes used by patients with pre-obesity/obesity. Methods The scientific information for this CPS is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership. Results This CPS outlines clinically relevant aspects of concomitant medications, functional foods, and many of the more common supplements as they relate to pre-obesity and obesity. Topics include a discussion of medications that may be associated with weight gain or loss, functional foods as they relate to obesity, and side effects of supplements (i.e., with a focus on supplements taken for weight loss). Special attention is given to the warnings and lack of regulation surrounding weight loss supplements. Conclusions This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on concomitant medications, functional foods, and supplements is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of pre-obesity/obesity. Implementation of appropriate practices in these areas may improve the health of patients, especially those with adverse fat mass and adiposopathic metabolic consequences.
Chapter
Plants have always been the primary source of food and medicine for humans. Plant extracts have received high interest as antimicrobials, flavor enhancers, preservation agents, and nutraceutical ingredients in the food industry. Plant extracts are exceptionally capable candidates to replace synthetic compounds, which render toxic and carcinogenic effects. Plant extracts exploited in food industry also pose some challenges based on the extraction strategies, stability, purity levels, regulatory issue, and cost-based factors.
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The objective of the present study was to identify factors correlated with the serum leptin concentration in women with knee OA. Fifty postmenopausal Japanese women with knee OA (age: 50-88 years) were recruited in our outpatient clinic. Plain radiographs of the knee were taken, and urine and blood samples were collected. Dual-energy X-ray absorptiometry (DXA) scanning was performed for the whole body and lumbar spine, and factors correlated with the serum leptin concentration were identified. A simple linear regression analysis showed that body weight, body mass index, whole-body bone mineral density (BMD), total fat mass, and total fat percentage, but not age, height, lumbar spine BMD, lean body mass, serum and urinary bone turnover markers, or the radiographic grade of knee OA, were significantly correlated with the serum leptin concentration. A multiple regression analysis showed that among these factors, only body weight and total fat mass exhibited a significant positive correlation with the serum leptin concentration. These results suggest that the serum leptin concentration might be related to increases in body weight and total fat mass, but not to BMD or bone turnover markers, in postmenopausal women with OA.