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Does Chitosan Promote Weight Loss?

Chitosan, produced by the deacetylation of chitin (a structural component of crustacean exoskeletons), is widely sold as a weight-loss product. These products claim that chitosan (or the soluble fibre produced when chitosan comes in contact with dilute acid in the stomach) can bind and reduce fat digestion and absorption to an extent that would promote weight loss. Of course, as a “natural” product, it is also promoted as being safe with no side effects and often backed with “testimonials” and wildly optimistic weight-loss claims. So does chitosan actually work? This question was the topic of a recent Cochrane Database Systematic Review by Andrew Jull and colleagues from the University of Aukland, New Zealand. The researchers searched electronic databases (MEDLINE, EMBASE, BIOSIS, CINAHL, The Cochrane Library), specialised web sites (Controlled Trials, IBIDS, SIGLE, Reuter’s Health Service, Natural Alternatives International, Pharmanutrients), bibliographies of relevant journal articles, and contacted relevant authors and manufacturers. Trials were included in the review if they were randomised controlled trials of chitosan for a minimum of four weeks duration in adults who were overweight or obese. Authors of included studies were contacted for additional information where appropriate. Fifteen trials including a total of 1219 participants met the inclusion criteria. Analyses indicated that chitosan preparations result in a statistically significantly greater weight loss of about 1.7 kg with a modest decrease in total cholesterol and blood pressure. However, the authors note that the quality of many studies was sub-optimal and that when they restricted analyses to larger and longer studies, the effects were substantially smaller than in the smaller studies. The authors conclude that while there is some evidence that chitosan may indeed be more effective than placebo in the short-term treatment of overweight and obesity, the results from the few high quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance. Clearly not enough evidence for me to recommend chitosan to any of my patients – my advise to them: save your money for treatments that work. AMS Edmonton, Alberta

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Googling Guggul for Weight Loss

Guggul, or rather guggulsterone, is the active ingredient in an age-old Indian Ayurvedic remedy derived from the gum resin of the guggul tree (Commiphora mukul), which has been shown to lower lipid and cholesterol levels. Claims have also been made regarding its usefulness as an antiobesity drug, although the data on this is far from consistent. A recent paper by Yang and colleagues from the University of Georgia, published in a recent issue of OBESITY, demonstrates that guggelsterone in fact does substantially inhibit adipogenic differentiation of cultured 3T3-L1 cells (a widely used in vitro model of fat cells). In this model, guggulsterone also promotes lipolysis as well as induces apoptosis of fat cells, albeit at higher concentrations. (link to abstract) Together, these findings appear to provide a biological mechanism to support the anti-obesity health claims for this compound. However, this does not mean that we now have a new natural “solution” to the obesity problem (although, as a brief excursion to Google confirms, guggul is already widely promoted and available for exactly that). Here are my reservations: 1) Fat cells are the safest place to store excess calories. Limiting the growth or destroying fat cells, without also targeting the state of caloric excess raises the issue of where those extra calories should go. Because they are in excess of what the body needs, they are not simply “burnt off”. Rather, the body now has to store them somewhere else, i.e. in non-fat tissue (for e.g. liver, muscle, etc.) – also referred to as “ectopic” fat deposition. There is now ample evidence that it is in fact this ectopic fat that causes the metabolic problems (e.g. diabetes) that are often associated with obesity. So if guggul prevents the formation of fat cells or destroys them (by apoptosis) the big question is: what happens with all the excess energy? If this now ends up in the form of fat stores in other organs like your liver or muscle, you are more likely to cause harm rather than reap any benefits. 2) Obviously, extrapolating from an in vitro finding to clinical benefits in patients is a long shot. While the data on guggul’s clinical antilipid effects appears well-documented, I am not convinced of any weight-loss effects thus far. Destroying fat cells, to me does not necessarily translate into weight loss unless the extra calories stored in those cells are actually burnt. For that… Read More »

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