• Garcinia cambogia offers a novel and natural product for weight management.

Weight management supplements are controversial products but they have a place in the nutritionals business. It has been a goal of many over-the-counter medicine businesses that being able to modify the satiating effects would prove valuable in the battle to reduce obesity (Trigueros et al., 2013). Obesity continues to increase in the developing worlds at an alarming rate.

One of the most intriguing is the extract of Garcinia cambogia which has been available for some years but is now being seen as a valuable additive in the armoury of clinically proven supplements for reducing weight.  Controversially, early studies have not always proved this point about weight loss. It appears particularly potent though with other supplements and is following a trend in product development of combining various ingredients to promote a particular function.

Hydroxycitric Acid

Garcinia cambogia extract owes its efficacy to hydroxycitric acid (HCA) which is 30% by weight of the fruit and is extracted from its rind. HCA is a derivative of citric acid and is found in two other Garcinia species, G. indica and G. atroviridis (Roongpisuthipong et al., 2007). The chemistry of HCA has been reviewed (Jena et al., 2002).

Hydroxycitric acid is commonly marketed as a weight loss supplement in its own right or combined with other supplements. It is thought to cause weight loss by competitively inhibiting the enzyme adenosine triphosphate-citrate-lyase which is a key enzyme in the citric acid cycle (Mattes and Bormann, 2000; Hayamizu et al., 2003; Preuss et al., 2004; Downs et al., 2005). The enzyme is based in the cytosol of the cell and catalyses the cleavage of citrate to oxaloacetate and acetyl-CoA. This leads to an increase in hepatic glycogen synthesis which leads to the feeling of satiety.  

HCA could also raise the availability and release of serotonin in the brain, thereby leading to appetite suppression (Toromanyan et al., 2007). Inhibition of carbohydrate metabolism might also be achieved by HCA inhibiting pancreatic alpha-amylase and intestinal alpha glucosidase (Yamada et al., 2007). It might also stimulate fat oxidation metabolism between meals (the interprandial period) (Westerterp-Plantenga and Kovacs, 2002).

The fruit is known as the Malabar Tamarind and is related to Mangosteen. It is grown in India and Southeastern Asia. It was often added to meals as a flavour and condiment and to generate a more filling feel which points to its appetite suppressing sensation. Suppression of hunger was seen as the main attribute of the fruit.

In the UK, the regulatory guidelines classify isolates and extracts comprising hydroxycitric acid (HCA) as a medicine  and so any product using this form would have to establish safety and efficacy which sounds counter-intuitive given the extent of the research on the extracts of Garcinia.

Weight-Loss Studies

Panksepp (1977) first identified the weight loss effect with HCA in a rat model.  A double-blind study with 89 women of mean age 40 and a body mass index (BMI) of 28 showed that those who consumed HCA (2.4g Garcinia; 1.2g HCA) compared to a placebo, daily for three months lost about 1.3kg (p=0.026) compared to the placebo group (Mattes and Boorman, 2000). The diet was controlled to 1,200 kcal and 30% fat. A later placebo-controlled diet with 135 subjects of mean age in the late 30s with a BMI of 31 showed that consumption with 1.5g of HCA vs. placebo for three months generated no changes whatsoever (Heymsfield et al., 1998).

Subsequent studies reinforced the view that HCA could cause weight loss in animal models (Leonhardt et al., 2001; Downs et al., 2005). There have been some recent reviews which systematically examine various reported human clinical trials with some strong meta-analysis (Igho et al., 2011; Onakpoya et al., 2011). The findings generally are dismissive of the efficacy of HCA and certainly not as effective as orlistat for example (Rucker et al., 2007).

Products using green tea, caffeine, guarana, L-theanine have all been using more than one of these ingredients to create a functional benefit message. Take  H3^xG for example which is a supplement using at least six clinically researched ingredients.

Natural Products Insider now consider Garcinia cambogia to be part of the disruptive innovation message when it comes to weight loss and weight management. Take Whisbih  RTD Super Green Tea manufactured by Chen Kou Wei Food  from Hong Kong which combines not only green tea, but Flammulina Mushroom extracts, dietary fibre, L-theanine and  L-glutamic acid amongst other ingredients.  Likewise, a few years ago Skinny Water from Jamaica produced a water containing 1.5g of Garcinia cambogia extract with 900mg of (-) hyroxycitric acid. This product claimed with its two key actives, to ‘help people lose and maintain their weight’.

Citrimax™ (Super Citrimax™) is a novel calcium-potassium hyroxycitric acid (HCA-SX) which is more soluble and bioavailable than the just the calcium form and has become a common ingredient of ‘negative calorie’ drinks. The acute oral toxicity studies show that CitriMax (HCA-SX) has a low acute oral toxicity and not likely to cause adverse reproductive or developmental effects. HCA-SX was not mutagenic in the absence or presence of metabolic activation¹.  Up to 2.8 mg/day is thought safe for human consumption. One study showed that administration of HCA-SX over a 80-day period produced a reduction I body weight and no significant changes to the major organs². A histopathological examination of the safety of high doses of HCA showed the ‘no adverse effect level’ (NOAEL) to be 51 mmol HCA/kg diet (389 mg HCA/kg BW/d), above which potent testicular atrophy and toxicity has been observed. The Super CitriMax product is covered by US patent No. 6,875,891.

There is a another mix of ingredients called Lisopresol which combines Garcinia cambogia with L-carnitine and ID-alG, a seaweed extract of Ascophyllum nodosum. Rats fed on a high fat diet were claimed to lose weight when fed Lisopresol which is believed to inhibit digestive enzymes such as lipase and alpha-amylase which would reduce both fat and carbohydrate metabolism or absorption (Terpend et al., 2012).

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References

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2- Mol Cell Biochem. 2004 May; 260(1-2) pp.171-86

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