Garcinia Cambogia is an extract from a fruit often called the Malabar tamarind, which has had quite an impact in the weight loss industry in the past year or so.
The Garcinia family grows throughout much of the tropical world, and the Malabar tamarind produces an orange to pumpkin-sized fruit that is a popular part of the diet in many South-east Asian countries. It is also used in traditional medicine in these cultures, where its sour flavour is believed to stimulate the digestive system.
It was promoted as a weight loss supplement by the American TV presenter, Dr Oz, who called it a ‘fat buster’ and gave the supplement huge public profile.
The sour flavour comes from hydroxycitric acids found in the fruit. These are related to citric acid, most commonly associated with the flavour of lemons, and it’s a derivative of these acids (called (-)-Hydroxycitric acid) that is thought to help with weight loss. A study on rats found that (-)-Hydroxycitric acid reduced the amount they ate and subsequently their body weight. This happened because the supplement stopped the production of some fatty acids. The weight loss was more than the reduction in the amount eaten would have accounted for.
However, this fat production process is much more important in rats than it is in humans and studies of human weight loss using Garcinia Cambogia have produced mixed results at best.
There have been a number of studies of Hydroxycitric acid as a weight loss agent. They were:
A 2011 study from the Center for Food and Nutritional Genomics Research at Kyungpook National University, in Daegu in South Korea. This study looked at two natural supplements – Glycine max leaves and Garcinia cambogia – to test their usefulness in reducing both weight and types of cholesterol. In the study, 86 subjects, who were all overweight, were given on of the two supplements (2g-a-day of each) or a placebo over 10 weeks and their body weight, cholesterol and diet (as well as several other measures) were checked before and after the 10 weeks. The scientists concluded that the supplements did not induce weight-loss or lower the percentage of body fat. No change in diet was attempted during the study.
A 2000 study from the department of foods and Nutrition at Purdue University in West Lafayette in America looked at (-)-Hydroxycitric acid as a weight loss agent. The study used 89 women, who were described as ‘mildly overweight’. They were put on a restricted diet for 12 weeks with just under half also taking 400-mg of Garcinia cambogia before meals, amounting to a daily dose of 2.4 g. All the participants lost weight, but the group on supplement lost more. The supplement did not appear to have an effect on appetite or feelings of fullness.
In 1998 a group of scientists at the Obesity Research Centre in Columbia University, New York, looked at Garcinia cambogia as an anti-obesity agent. The participants were all overweight and were studied for 12 weeks to see if the supplement would reduce body weight or fat mass. Their diets were controlled and either given 1,500 mg of hydroxycitric acid every day or a placebo. Of the 135 subjects quite a large number dropped out of the study, but those who stayed in were able to lose a ‘significant amount’ of weight. However, there was no statistically significant difference between those patients who had been given the supplement and those who were given nothing.
In 2011, the Journal of Obesity published a review of previous studies conducted by scientists from the University of Exeter Medical School in the UK. They found that 23 studies had been carried out which could be looked at and chose 12 for their study. This study raised concerns about the methodologies of some of the studies, saying that none of them had lasted long enough, for example. It did find some weight loss reported in trials, but concluded that on the evidence they had the effect was small and when they tightened up the criteria for which trials were included this effect was said to be ‘no longer statistically significant’. The study’s authors have called for more and better research on the supplement in the future.
Live Science looked at some of the evidence around Garcinia cambogia in August 2013. It reported the traditional use for digestive problems and said that hydroxycitric acid had been discovered in the fruit’s rind in the late 1960s. According to Catherine Ulbricht, a senior pharmacist, the acid’s action can stop – according to some studies – sugar being turned into fat. Live Science also reported on animal trials which showed the weight-loss effect and reduced fat. They said that the mixed evidence that Garcinia cambogia produced weight loss in humans would not be strong enough for it to be marketed as a drug for that purpose in the USA. Ulbricht warned about the variable quality and quantities of different brands of supplement. There was also a warning about possible side effects from the use of Garcinia cambogia. The fruit seems to be safe. However, the extract can cause lower blood sugar and cause complications with diabetes treatments. There have not been studies on its effects on women who are pregnant or breastfeeding. Ulbricht warned that dementia sufferers may also suffer adverse interactions with Garcinia cambogia. The US Food and Drugs Administration (FDA) issued a warning about a related supplement called Hydroxycut in 2009, which – at the time – contained Garcinia cambogia extract.
Further research include another meta-analysis of nine trials in the Journal of Obesity. The studies included in the survey, 706 people were given the supplement. The studies found a ‘statistically significant’ effect on weight loss, albeit a small one which wasn’t clinically relevant. The studies warned about side-effects including colds, stomach problems, headaches and rashes.
There was a warning attached to a 2005 study on rats which warned about possible damage to the testes. These warnings, however, have been somewhat calmed by a 2008 study on humans. A study in Critical Reviews of Food Science and Nutrition published in 2012 said that the use of Garcinia cambogia seemed to be safe. The evidence suggest a positive correlation between Garcinia Cambogia and weight loss benefits.