Taking a daily dose of chitosan as a supplement had only a slight effect on weight loss in a new research on obese volunteers.
Chitosan supplements, derived from the chitin naturally present in large quantities in shellfish, are marketed as a weight loss product as the fibers has been shown to bind fat (that’s is why they are called fat binder) in the intestine, blocking its absorption. Not all trials have confirmed its effectiveness in weight loss management.
The new research, published in the September 2004 issue of the International Journal of Obesity, is one of the largest to date.
The researchers assigned 250 obese adults to receive either 3 grams of chitosan daily or a placebo for a period 24 weeks long. All participants received identical dietary and lifestyle recommendation for weight loss.
The researchers from the Clinical Trials Research Unit in the University of Auckland find out that people who took the chitosan lost more body weight than who took just the placebo, but the different between the two group was small. People who took the chitosan pills lost an average of 0.9 pounds compared to a 0.4 pound gain in the people who took the placebo pills.
Analogous small variations were seen in the total and LDL cholesterol levels and there were no considerable differences between groups for any of the other measured outcomes such as body mass index, waist circumference, body fat percentage, blood pressure or quality of life.
“We do not know of any limiting factors in our study that would have prevented a greater effect on weight loss. Our trial was designed and analysed according to international clinical trial standards and is the largest trial of chitosan to date with the most outcome measures,” stated Dr Cliona Ni Mhurchu, senior research fellow at the Clinical Trials Research Unit.
“It is unlikely that a longer follow-up period would change the outcome since it is common in weight loss studies to lose more weight in the earlier than in the later stages,” she adds. “Our dose is similar to that used in other studies and is greater than that advised by the manufacturer.”
The product tested was a beta-chitosan supplement derived from New Zealand squid pens. It was 76% deacetylated and had a molecular weight of 130,000.
But James France, general manager of Wilkie Resources which markets the LipoSan Ultra brand chitosan in the United States, notes that there are considerable issues with bioavailability of chitosan, which could preclude some products from having a noteworthy effect.
“Chitosan is a very big fiber that isn’t easy to get into a solution. Regular chitosan is so tightly bound that it does not dissolve enough in the stomach to allow it to interact with the fat.”
The LipoSan Ultra chitosan has been customized using succinic acid which holds the fiber separately enough to allow it to dissolve, creating a gel with fat cells and binding them so that they move out of the gastrointestinal tract before being broken down by lipase.
The former manufacturer of LipoSan, Vanson Halosource, carried out a randomized, double-blind, placebo controlled clinical trial of chitosan for weight loss on 59 mildly obese women. After 8 weeks a statistically considerable reduction in weight was seen in the chitosan group.
“I don’t refute their results [the New Zealand trial] but you need to look at how this particular product behaves,” says France.
The Truth about Natrol
Natrol, Inc., and its president Elliott Balbert have agree to pay $250,000 to settle charges that they made false and ambiguous advertising claims for their chitosan-based weight loss supplement, some of which contained more lead than permitted by state law.
Starting in 1998, they marketed a product named Absorbitol Fat Binder, claiming that the chitosan ingredient in the product would cause the user to lose weight by absorbing fat and that it could bind “178% more fat than other brands” and 10.8 ml of fat “per gram of active ingredient.”
In 2001, it began marketing Chitosan 500 mg, Ultra Chitosan Fat Intercept, and Ultra Chitosan Fat Intercept Plus with analogous claims.
An examination found that there isn’t any valid scientific proof to support claims that the ingestion of chitosan causes fat to be “trapped” or “bound” in the human gastrointestinal tract, or that the use of chitosan-based dietary products causes any considerable or evident weight loss results.
The research also exposed that Chitosan 500 mg, Ultra Chitosan Fat Intercept and Ultra Chitosan Fat Intercept Plus contained lead in amounts that exceeded the 0.5 microgram daily limit allowed by Proposition 65.