Herbal preparations for obesity: are they useful?

The opportunities for additional research in this area are plentiful. Unfortunately, there has been relatively limited funding for research on herbal supplements compared with the amount of funding that is available for research on pharmaceuticals. Botanical dietary supplements often contain complex mixtures of phytochemicals that have additive or synergistic interactions. For example, the tea catechins include a group of related compounds with effects that are demonstrable beyond those that are seen with epigallocatechin gallate, the most potent catechin. The metabolism of families of related compounds may be different than the metabolism of purified crystallized compounds. In some cases, herbal medicines may simply be less purified forms of single active ingredients, but in other cases they represent unique formulations of multiple, related compounds that may have superior safety and efficacy compared with single ingredients. Obesity is a global epidemic, and traditional herbal medicines may have more acceptance than prescription drugs in many cultures with emerging epidemics of obesity. Several ethnobotanical studies found herbal treatments for diabetes, and similar surveys, termed bioprospecting, for obesity treatments may be productive. Beyond increasing thermogenesis, there are other biological rationales for the actions of several different alternative medical and herbal approaches to weight loss. For example, several supplements and herbs claim to result in nutrient partitioning so that ingested calories will be directed to muscle, rather than fat. These include an herb (Garcinia cambogia), and a lipid which is the product of bacterial metabolism (conjugated linoleic acid). Moreover, a series of approaches attempt to physically affect gastric satiety by filling the stomach. Fiber swells after ingestion and has was found to result in increased satiety. A binding resin (Chitosan) has the ability to precipitate fat in the laboratory and is touted for its ability to bind fat in the intestines so that it is not absorbed. In double-blind studies, however, this approach was found to be ineffective. There are two key attractions of alternative treatments to obese patients. First, they are viewed as being natural and are assumed by patients to be safer than prescription drugs. Second, there is no perceived need for professional assistance with these approaches. For obese individuals who cannot afford to see a physician, these approaches often represent a more accessible solution. Finally, for many others, these approaches represent alternatives to failed attempts at weight loss with the use of more conventional approaches. These consumers are often discouraged by previous failures, and are likely to combine approaches or use these supplements at doses higher than are recommended. It is vital that the primary care physician is aware of the herbal preparations that are being used by patients so that any potential interaction with prescription drugs or underlying medical conditions can be anticipated. Unfortunately, there have been several instances where unscrupulous profiteers have plundered the resources of the obese public. Although Americans spend $30 billion per year on weight loss aids, our regulatory and monitoring capability as a society are woefully inadequate. Without adequate resources, the FDA resorted to "guilt by association" adverse events reporting, which often results in the loss of potentially helpful therapies without adequate investigation of the real causes of the adverse events that are reported. Scientific investigations of herbal and alternative therapies represent a potentially important source for new discoveries in obesity treatment and prevention. Cooperative interactions in research between the Office of Dietary Supplements, the National Center for Complementary and Alternative Medicine, and the FDA could lead to major advances in research on the efficacy and safety of the most promising of these alternative approaches.