Uncertainty over Garcinia's weight-loss claims
DOES IT WORK?Further studies needed to determine effects, writes DÓNAL O'MATHÚNA
GARCINIA SPECIES are widely used in Thai and Indian cuisine. The fruit, especially from Garcinia cambogia, has developed a reputation among those seeking to lose weight and build muscle.
Extracts of the fruit contain up to 50 per cent hydroxycitric acid, which is believed to be the active ingredient.
Earlier this year, the Food Safety Authority of Ireland (FSAI) issued a product alert, calling on consumers to discontinue using all “Hydroxycut’’ products.
The product name comes from hydroxycitric acid, which is added to some of the products in the form of Garcinia cambogia. The FSAI called on retailers not to sell these products, but they can still be found on Irish websites and remain available elsewhere.
The FSAI alert is based on recent case reports suggesting a link between Hydroxycut products and liver damage. The Canadian manufacturer voluntarily withdrew its products from the US market after the Food and Drug Administration (FDA) issued a consumer warning.
The weight-loss properties of hydroxycitric acid have been studied since the 1960s. Laboratory tests have shown that it inhibits an enzyme involved in producing body fat from other foods. Research also suggested that hydroxycitric acid may suppress appetite and reduce food intake in animals.
These results led to a series of small human studies in the early 1990s which produced contradictory results. One of the largest randomised controlled trials of hydroxycitric acid to date was published in 1998.
More than 130 overweight men and women took either 1.5g hydroxycitric acid (3g Garcinia cambogia) daily or placebo while also eating a high-fibre, low-calorie diet. Both groups lost weight during the study, but the two groups did not differ in the amount of weight lost or their body fat. Some have claimed that the diet may have interfered with the effects of the Garcinia.
At this point, close to a dozen randomised controlled trials have been conducted with Garcinia, although some of them have used it in combination with other herbs. Some of the studies have produced positive effects, although the quality of the research was sometimes poor.
The safety of hydroxycitric acid has been evaluated in recent studies, in addition to the long traditional use of Garcinia. In general, the herb and food supplements have not produced adverse effects and are generally regarded as safe at recommended doses.
Then several case reports were published in the medical literature of liver damage following consumption of Hydroxycut products. In 2009, the FDA reported that it had received 23 cases of serious health effects from these products.
The damage ranged from jaundice to liver failure requiring transplantation and one death. Although the number of cases is low, their seriousness led to the consumer alerts mentioned above and subsequent product withdrawals.
Determining the precise cause of the liver damage is difficult. Hydroxycut contains a number of herbs and other agents, with different mixtures used in different products. Some formulations do not contain any Garcinia cambogia.
The case reports have not been able to identify which ingredient, or combination of ingredients, may have led to the liver damage.
Further research is needed to understand the precise source of these problems.
Hydroxycitric acid from Garcinia cambogia shows some potential as a weight-loss product. However, the available studies are variable in their quality and the types of products tested. More studies are needed to demonstrate whether or not the products are effective and safe.
The reports of potential liver damage associated with Hydroxycut products point to the need for careful evaluation and monitoring of all herbal remedies.
When products contain several herbs, the precise source of positive or negative effects is difficult to determine. Given this uncertainty, and the complexity of weight loss, people should rely on the standard, proven methods of weight loss: reduce calorie intake, increase physical activity and find others to support your efforts.
While some supplements may be helpful, Hydroxycut should be avoided.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University. He is author of Alternative Medicine: The Christian Handbook, Updated and Expanded Edition, Zondervan, 2007