In the search for the perfect figure without having to starve, we are often tempted to turn to one or more of the many slimming supplements on the market at the moment. We are often asked about Garcinia cambogia (GC) so we have picked apart the existing evidence for this supplement. If you are thinking of taking any product containing GC or HydroxyCitricAcid (HCA), read on..
First of all, please forgive this article being a little dry.
We'll begin with a list of the papers considered with links to the abstracts. We examined all reported clinical trials and reviews after the 2011 review, which was sufficiently high quality to be definitive up to that point:
- Allen et Al November 2014 - A case report of a patient suffering severe heart problems 2 weeks after starting GC. This may or may not be related to the supplement use - it is impossible to be sure.
- Chong et Al October 2014 - this paper compared a proprietary GC product with placebo in 91 patients. Patients were given a personalised weight loss diet by the This seems to have been a very high quality study with good methodology. Both groups lost a small amount of weight though neither lost as much as would be expected from the diet alone. The GC group lost slightly more weight but though the study claims a statistically significant difference, the weight loss and group sizes were sufficiently small that just a couple of aberrant results could account for this. Disappointingly, the lead researchers were employees of the company marketing the supplement.
- Kim et Al August 2013 - A study in mice allowed free access to a high fat diet howed that GC could inhibit central fat deposition and liver fat deposition but increased liver fibrosis and signs of liver stress. A quality study but limited by being animal based rather than human.
- Vasques et Al June 2014 - A study in a minor journal shows that GC can improve adverse lipid profiles in overweight women. A small number of patients with very wide age range makes this a poor study.
- Astell, Mathai and Su August 2013 - A review of evidence in a minor journal concludes there is insufficient evidence of safety or benefit to recommend GC.
- Egras et Al August 2011 - A very high quality evidence-based review of the data to that point in a prestigious journal. The evidence supports GC being well tolerated but not effective for weight loss.
In trying to answer the question of utility for any product, whether natural or otherwise, it is important to consider the following points:
- Is it effective - does the product perform as expected?
- Is there a plausible mechanism of action - can the effects be explained by known scientific evidence? Does the proposed mechanism have a scientific basis?
- Is it safe - there are potential adverse effects from any medication but are these well documented: is there good evidence of safety or ongoing monitoring?
For GC, testing against these criteria:
Effectiveness: Studies to date have been small scale, and the only reasonable quality trial suffers from critical investigatory bias potential and a small sample size. No studies have been performed beyond 12 weeks which makes it impossible to show significant benefit in maintaining weight loss. Untill studies extending beyond 12 months have been performed in large populations the effectiveness of GC must be considered doubtful.
Plausible Mechanism: There is a plausible mechanism which has been well investigated. The compound interferes with fatty acid synthesis (full details are found in the Egras et Al review) and has been shown to reduce adipose tissue formation in animal studies.
Safety: There are serious safety concerns about the use of GC with several reported cases of severe liver side effects and one of severe heart problems. Evidence of the association between GC and liver damage is concerning in animal studies but there is no ongoing safety surveillance programme so it is possible that the small number of reported cases in humans underestimates the risk.
Whether you take a medication or not requires a balanced decision. All medications have risks and some have benefits. If you wish to take Garcinia cambogia supplements, the evidence to date suggests that there is a risk that it may cause liver damage however real world experience is that there are very few serious adverse effects attributed to GC. There is, however, no reliable evidence that it promotes weight loss in humans and even the most optimistic study (Chong et al) showed a 1.3Kg mean extra weight loss after 12 weeks.
For us, we feel that the evidence for GC is better than for many supplements but simply does not add up to it being worth taking. It is, however, based on current evidence, not dangerous enough to advise you not to take it if you really want to. Do be aware that there are some potentially serious side effects and that you could get more benefit than the best study in favour of GC by doing 20 minutes of moderate exercise each day, an intervention proven to improve heart health and which costs nothing.