Garcinia cambogia Uses and Evidence

Garcinia cambogia
Uses and Evidence
            by Sarah Penney, MSc, ND
            Hamilton Health & Wellness Centre
            865 Upper James St.
            Hamilton, ON
            www.HamiltonND.ca

                                              The prevalence of overweight and obesity
                                              has skyrocketed in North America over
                                              recent years, and weight management
                                              strategies employed have had little
                                              widespread success. Both science
                                              and the public have been interested in
                                              natural and synthetic weight loss aids for
                                              decades, the most recent slimming agent
                                              being Garcinia cambogia (G. cambogia)
                                              and its extract (−)‑hydroxycitric acid
(HCA). This extract can be found in the Garcinia family of plants native to South Asia,
India, and parts of Africa, and is marketed in hundreds of products, both alone and in
combination with other ingredients. HCA is thought to work as both a weight-loss agent,
by inhibiting an enzyme responsible for converting carbohydrates into fats, and as an
appetite suppressant, by increasing a hormone called serotonin in the brain.[1] Whether
or not these benefits hold true in human trials, HCA and G. cambogia supplements
have become one of the hottest products in the multibillion dollar weight-loss industry.
Is G. cambogia really the magic bullet we are looking for? Let’s look at the evidence
behind some of these health claims, and see if this trend has lasted for a reason other
than promotion by Dr. Oz.

                                                Weight Loss and Appetite
                                                Suppression
                                                Weight management is one of the most
                                                common health concerns on our minds,
                                                and for good reason. Overweight and
                                                obesity are important underlying causes
                                                to conditions like diabetes, heart disease,
                                                and even types of cancer. The natural-
                                                health industry has not been blind to

this trend, and it’s easy to walk into any supplement dispensary and find a section
dedicated to weight loss. G. cambogia and HCA have recently become available on
Canadian markets and can now be found among these supplements, although many
products were previously accessible through the USA and online. The human evidence
investigating the weight-management effect of G. cambogia and HCA have been
mixed, and results from different studies may depend on the extract or product used,
study design and duration, potential bias through sponsorship, and other confounding
factors like diet changes of the participants. Several rigorous reviews exist on the use of
G. cambogia and weight loss or appetite that summarize these trials, the most recent of
which was published in 2013. This report identified five human trials using G. cambogia
or HCA, each involving over 20 overweight or obese participants, for longer than two
weeks, that met multiple other requirements for inclusion. Although five trials may not
sound like many, this herb has the most available research among any of the popular
natural weight-management supplements that were studied. Most trials looked at both
appetite and weight change over the duration of study, and only one reported a positive
effect on appetite control in the group taking G. cambogia.[2] In this study, participants
took a highly absorbable calcium–potassium supplement containing 2.8 g of HCA, at
least 30 minutes before meals, for eight weeks. Unfortunately, most of the products
available on our market are in a calcium salt form, which decreases absorption of HCA,
thus likely impacting effectiveness. Two of these studies also reported a significant
decrease in body weight at the end of their trials, although neither of them reported the
content of HCA in their supplements. One administered 2.4 g of G. cambogia daily for 12
weeks, while the other used a combination product containing G. cambogia, caffeine,
and ephedra for 39 weeks. It is difficult to determine the value of the G. cambogia
when used in a combination product with other known weight-loss agents like in this
trial. A previous review published in 2011 considered nine trials in their analysis, several
of which overlap with the 2013 review, and concluded G. cambogia has a short-term
and small magnitude of effect, if any.[3] Further rigorous trials isolating G. cambogia are
needed to establish impact on weight management.

Cholesterol Control
High cholesterol is a clinical finding often associated with overweight and obesity, and is
an important predictor of long-term health consequences like heart attack and stroke.
Although effective medications are marketed to target this issue, many people look for
alternative solutions due to risk of side effects, cost, or personal preference. Interest in
the use of G. cambogia to lower cholesterol is currently mounting in the research world
regarding the potential effect of HCA on cholesterol production.

HCA seems to act by inhibiting an enzyme called ATP-citrate lyase, which is involved in
the production of fatty acids.[4] One trial published in 2014 examined the use of 2.4 g

of G. cambogia (50% HCA) taken for
                                               60 days before meals by 30 overweight
                                               subjects. Authors reported that while this
                                               treatment had no effect on LDL (“bad”
                                               cholesterol) or HDL (“good” cholesterol),
                                               it did significantly lower triglyceride
                                               levels by 28%; triglycerides are a type
                                               of fat that have been correlated with an
                                               increased risk of stroke.[4] Another trial
                                               published in 2008 has also examined
                                               this effect, dosing a combination product
                                               of G. cambogia (2.4 g, 52% HCA) and a
                                               fibre-like compound called glucomannan
                                               to 32 subjects for a 12 week period.
                                               Authors reported a positive lowering
                                               effect on total cholesterol and LDL levels
                                               in the treatment group, even though there
was no effect on triglyceride levels or weight.[5] It is again hard to isolate the effect of
G. cambogia from these results, due to the inclusion of an additional ingredient that
may lower cholesterol levels. A third intervention previously described also measured
several cholesterol parameters during their eight-week trial, reporting a significant
decrease in total cholesterol, LDL, and triglycerides.[2] Interestingly, HDL also increased
in their treatment group, which is a marker of decreased cardiovascular risk. Although
these results seem promising, further human study is necessary before conclusions are
drawn on the effect of G. cambogia and HCA on cholesterol levels.

                                Blood Sugar Balance
                                Several trials have also examined blood sugar control
                                as an outcome during treatment with G. cambogia or
                                HCA, which is important for both long-term health and
                                weight management. Results have unfortunately been
                                less than promising. Two studies previously described
                                measured glucose levels and insulin levels, respectively,
                                in their trials, but both reported no significant changes
                                after their treatment periods.[4, 5] Interestingly, one
                                additional study has been completed in eight athletes,
                                demonstrating that 500 mg of HCA after exercise
                                lowered blood sugar levels and enhanced fuel recovery
                                in muscle tissue.[9] Although this small study may
                                indicate that HCA does have some situational influence

on blood sugar regulation, these are clearly not the conditions under which it is often
used. G. cambogia has been promoted as a blood sugar–lowering agent, possibly due
to more positive results in animal trials, but the obvious lack of clinical support for these
conclusions makes this marketing questionable. Blood sugar levels are an important
parameter that will hopefully be measured in future weight-management trials using
HCA, especially those involving exercise.

                                               Side Effects and Safety
                                               An important consideration in the marketing
                                               of any over-the-counter supplement is
                                               safety for the general public. G. cambogia
                                               and its isolated ingredient HCA are
                                               relatively new to the supplement market in
                                               North America, although this fruit has been
                                               historically consumed as a flavouring for
                                               certain dishes in its native environments.
                                               Clinical trials of G. cambogia have not
                                               highlighted any significant adverse effects
                                               that seem to arise, and both animal and
                                               human trials have demonstrated relative
                                               safety with regards to mortality, toxicity,
                                               and liver health at reasonable doses of
2.8 mg HCA per day.[6, 7] One clinical trial did, however, report twice the amount of
GI effects in their treatment group of 135 individuals taking 1.5 g HCA per day.[8] One
issue in drawing conclusions about safety is the duration and size of the studies. Most
studies still have a relatively small treatment group, and the longest trial duration has
been 12 weeks, which does not necessarily indicate safety with long-term use. There
have been several case reports of toxicity involving combination products containing
HCA as an ingredient, such as Hydroxycut, but it is impossible to identify HCA as the
offending ingredient in these cases. Hydroxycut and HCA do not seem to present any
significant risk of interactions with medications, although theoretical interactions exist
with drugs that lower blood sugar due to a potential additive effect. There has also
been one case report involving a condition called rhabodmylosis (muscle breakdown)
after the use of a combination product containing Garcinia in conjunction with a statin
medication.[9] Again, direct causation due to G. cambogia is difficult to establish.

G. cambogia and HCA have had massive success in the market of weight-management
supplements, and are only becoming more widespread through inclusion into many
combination products. Although results seem to be mixed when it comes to weight
loss in human trials, the debate continues and ongoing research will narrow down

the value of HCA and its infamous “fat-burning” abilities in the near future. Preliminary
research investigating effects on cholesterol levels has been promising, although results
are far from conclusive. The exact effect HCA has on the different types of cholesterol is
yet to be elucidated. Treatment seems to be generally well-tolerated, and no concerns
regarding toxicity have been raised, making it a relatively safe product for the general
public. Time will tell if Garcinia cambogia and HCA are the panacea the Western world
is searching for to alleviate the rising epidemic of obesity and diseases of lifestyle.

References
1.    Astell, K.J., M.L. Mathai, and X.Q. Su. “Plant extracts with appetite suppressing properties for body weight control: A systematic review of
      double blind randomized controlled clinical trials.” Complementary Therapies in Medicine Vol. 21, No. 4 (2013): 407–416.
2.    Onakpoya, I., et al. “The use of Garcinia extract (hydroxylic acid) as a weight loss supplement: A systematic review of meta-analysis of
      randomized clinical trails.” Journal of Obesity Vol. 2011 (2011): 509038.
3.    Preuss, H.G., et al. “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 & Metabolism Vol. 6, No. 3 (2004): 171–180.
4.    Vasques, C., et al. “Hypolipemic effect of Garcinia cambogia in obese women.” Phytotherapy Research Vol. 28, No. 6 (2004): 887–891.
5.    Vasques, C.A. and S. Rossetto. “Evaluation of the pharmacotherapeutic efficacy of Garcinia cambogia plus Amorphophallus konjac for the
      treatment of obesity”. Phytotherapy Research Vol. 22, No. 9 (2008): 1135–1140.
6.    Chauh, L.O., et al. “In vitro and in vivo toxicity of Garcinia or hydroxycitric acid: A review.” Evidence-Based Complementary and Alternative
      Medicine Vol. 2012 (2012): 197920
7.    Marquez, F., et al. “Evaluation of the safety and efficacy of hydroxycitric acid or Garcinia cambogia extracts in humans.” Critical Reviews in Food
      Science and Nutrition Vol. 52, No. 7 (2012): 585–594.
8.    Heymsfield, S.B., et al. “Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent: A randomized controlled trial”. JAMA Vol. 280,
      No. 18 (1998): 1596–1600.
9.    Cheng, I.S. “Oral hydroxycitrate supplementation enhances glycogen synthesis in exercised human skeletal muscle.” The British Journal of
      Nutrition Vol. 107, No. 7 (2012): 1048–1055.
10.   Mansi, I.A. and J. Huang. “Rhabdomylosis in response to weight-loss herbal medicine”. The American Journal of the Medical Sciences Vol. 327,
      No. 6 (2004): 356–357.