We are all aware of the fact that slimming is a mega-dollar industry. With millions, if not billions of people of all ages struggling to lose weight, and very few pharmaceutically effective medications available to assist them, the desperate public will literally clutch at straws. 

Every week sees the launch of a new “miracle” diet pill or potion and a “surefire” diet guaranteed to help believers shed kilos like magic.

Recently Garcinia cambogia became the flavour of the year. If you search the internet for information on this exotic fruit extract you will be assured that this is finally the miracle we have all been waiting for, which will produce dramatic weight loss. Endorsements by various TV personalities and other luminaries have added to the allure of Garcinia cambogia slimming products.

According to a recent local study from the  Tshwane University of Technology (TUT) “this small fruit, reminiscent of a pumpkin in appearance, is currently most popularly used and widely advertised as a weight-loss supplement”. 

The good side

But just how effective is this plant for shedding the kilos? 

The comprehensive overview from TUT suggests that studies have shown that “the extracts as well as (-)-hydroxycitric acid (HCA), a main organic acid component of the fruit rind, exhibited anti-obesity activity”. It also regulates the serotonin levels related to satiety, leading to reduced food intake. 

“According to clinical trial reports, Garcinia extracts were beneficial to obese individuals in many cases. In addition, studies on the toxicity and observations during clinical trials indicate that Garcinia is safe to use. Most of the negative reports have been related to cases where multi ingredient formulations were consumed and the effect could not be attributed to a specific ingredient.”

The research does, however, caution against an increase in serotonin, especially in people who take medicines that are already increasing serotonin levels, such as SSRIs. Research into these effects has not been conducted. 

“Moreover, regulatory authorities should provide and enforce legislation requiring the compulsory basic safety demonstration of supplements pre-marketing and develop post-marketing surveillance systems,” the study concluded. 

The bad side

Dr Ingrid van Heerden, a registered dietitian, is of opinion that we should be cautious of Garcinia, since it has not undergone rigorous testing. What follows is reviewed information from her pen, including her final verdict:

Often, once a person who wants, or needs to lose weight, is hooked on the promise of a slim, sexy figure, they are sucked into the deception. If the drops, wafers or powders don’t work, well then it is the fault of the user who did not adhere to one or other often impossible instruction such as “stick to a 500 kcal/day diet” or “drink 5 litres of water a day”, never that of the diet pill. 

When eventually science and legislation catch up with the manufacturers, they calmly take product A off the market, change their formulation slightly, change the name to product B, and then blithely sell product B using the same advertising gambits as before, raking in the money and pulling the wool over everyone’s eyes all over again.

In keeping with the ever-changing slimming product ranges, there are what one can call “ingredients of the year” (sometimes an ingredient lasts for only three to six months, but some have longer life spans, and then of course some are resurrected every two to three years).

We have had apple cider vinegar (which has made many a comeback over the years), green tea (which has earned some merit in scientific studies), hoodia (which just does not manage to produce the research results that will make it a front-runner), willow bark (or salicylic acid which is good for aches and pains but not as efficacious for slimming), and good old caffeine (which has a diuretic effect thus helping you lose weight until you replenish the water in your body, and also a stimulant effect when taken in large quantities that can be potentially dangerous), to name but a few.

While it is perfectly possible that more extensive and well controlled scientific studies will reveal that an extract of Garcinia cambogia which contains a chemical called hydroxycitric acid (HCA) will assist weight loss, we are at present not yet sure how this tamarind or brindall berry or brindleberry or Garcinia gummi-gutta works, what side-effects it may or may not have and what dosage is required to achieve really significant weight loss.

But I hear you say: “For once we have a number of scientific studies that were carried out with Garcinia cambogia, so what’s the problem?”

Well some of the studies did not show any weight loss differences between patients who took Garcinia pills and those who took dummy pills, while other studies did show differences in weight loss with the subjects taking pills containing Garcinia losing slightly more weight than those that did not (Marquez et al, 2012).

Some of these weight loss differences were not exactly exciting either, so we can’t say for sure that Garcinia cambogia does promote weight loss. It also seems likely that this is not the wonder pill it is made out to be.

In addition, many of the studies conducted to date have been flawed (Critchley, 2013) . What that means is for example that in one study the control and experimental subjects were not well matched (i.e. they did not have the same starting weight, age, percentage of body fat etc.), while in other studies too few subjects were used for the results to be significant.

For the results of studies to be plausible one has to compare “apples with apples” (i.e. well-matched subjects and controls) and you need more than just a handful of subjects to produce the same result.

On the positive side, we can say that there is some evidence that Garcinia cambogia products may aid weight loss over a period of 12 weeks. No studies have been conducted for longer periods as yet (Marquez et al, 2012), which is also regarded as a drawback.

Safety issues

There is also at present an argument about the safety of pills containing Garcinia cambogia – one group of researchers slates the pills as dangerous and hepatotoxic (causing liver damage) (Kim et al, 2013), while another group refutes this (Clouatre & Preuss, 2013). Marquez and his coworkers (2012) state that “at the doses usually administered, no differences have been reported in terms of side effects or adverse events (those studied) in humans between individuals treated with G. cambogia and controls.”  

Ano Lob (2009), a public health consultant in the United States has published a warning regarding the hepatotoxicity of a weight loss product called “Hydroxycut”, which contains Garcinia cambogia. The author collected case reports of patients who developed liver toxicity associated with the above mentioned weight loss product.

Evidently approximately one million units of this hydroxycitric acid product are sold per year in the USA. The patients who developed hepatotoxicity reported symptoms of fatigue, nausea, vomiting, cramps, fever, chills, abdominal pain, and jaundice.

While the number of hepatotoxicity cases reported were very few, Lob points out that monitoring of adverse events associated with dietary supplements such as these weight loss products is woefully inadequate in America (as is the case in many other countries, including South Africa), with the FDA only receiving about 1% of these negative reports.

According to Lob (2009), the Poison Control Centres in the USA are more likely to receive reports of adverse events associated with dietary supplements but are not equipped to coordinate such findings.

He cites the truly sobering example of a product called “Metabolife 356″ which was sold as a weight loss supplement in America. Lob’s states that the manufacturers received 14 000 reports over a period of five years that documented “serious adverse events associated with their ephedra-containing product” which included heart attacks, strokes, convulsions and fatalities.

The manufacturers did not inform the FDA or any other US government authority of these reports. As astounding as this may sound, manufacturers of dietary supplements are not required to meet any of the specifications that are strictly enforced when it comes to food and pharmaceutical products (medicines), so they can use this “ethical loophole” not to publish reports of negative and harmful events.

Eventually these events came to light and ephedra-containing products for slimming and other uses were banned in the USA.

The implication contain in Lob’s warning is that HCA or Garcinia cambogia extract may also be potentially toxic unless sufficient, reliable evidence to the contrary is made available.

Conclusion

At the present moment, we do not know enough about slimming products that contain Garcinia cambogia extract or HCA to freely recommend its use. I tend to agree with Astell and coworkers (2013) who conducted a systematic review of double blind randomised controlled clinical trials to assess the evidence available on the efficacy of current dietary supplements used to control appetite and/or weight.

These authors concluded that “According to the finding from this systematic review, the evidence is not convincing in demonstrating that most dietary supplements used as appetite suppressants for weight loss in the treatment of obesity are effective and safe.”

While we wait for more extensive and conclusive evidence obtained with larger numbers of well-matched test subjects treated for longer periods with the “gold standard” of double blind randomised controlled clinical trials, rather avoid using any weight-loss supplement that has not been tested thoroughly.

^{References:
(Astell KJ et al (2013). Plant extracts with appetite suppressing properties for body weight control: a systematic review of double blind randomized controlled clinical trial. Complement Ther Med, 21(4):407-16; Clouatre DL & Preuss HG (2013). Hydroxycitric acid does not promote inflammation or liver toxicity. World J Gastoenterol. 19(44):8160-2; Crtichley G (2013). Garcinia cambogia – is it really a miracle weight loss supplement?; Lob A (2009). Hepatotoxicity associated with weight-loss supplements: A case for better post-marketing surveillance. World J Gastoenterol. 15(14):1786-1787; Marquez F et al (2012). Evaluation of the safety and efficacy of hydroxycitric acid or Garcinia cambogia extracts in humans. Crit Rev Food Sci Nutr, 52(7):585-94)}

Additional reporting by Joshua Carstens