What Is It?
The shells of crabs, lobsters, and other crustaceans contain a nondigestible fiber called chitosan. Extracted and taken in supplement form with meals, chitosan reportedly encourages weight loss by binding to fat molecules in the digestive tract, preventing the body from absorbing the fat.
Whether chitosan is safe and effective as a diet aid remains controversial, however. Some small studies have found that taking the supplement may result in weight loss. In one trial, people who used chitosan for a month in conjunction with a calorie-controlled diet lost, on average, 8% of their body weight. This translates into 16 pounds for a 200-pound person. How much this was due to the chitosan and how much to the calorie restriction is unknown.
Other studies, however, have not reported such positive findings. A carefully designed 1999 trial in England involving 34 overweight individuals, for instance, found that chitosan supplements were no better than a placebo in reducing body weight.
Some advertisements encourage taking chitosan so that you can “indulge” in a fatty meal. This is definitely not the case. While chitosan does work to bind to some of the fats in your digestive tract, it certainly doesn’t cover them all. The bottom line is that anyone wishing to try chitosan for weight loss will have to watch their total calorie intake, reduce the fat in their diet, and exercise.
Researchers are still examining whether chitosan may lower cholesterol (another effect of its fat-binding qualities) or even have a role to play in controlling ulcers, high blood pressure, and arthritis.
General Interaction
Although chitosan is quite safe, it’s possible that, in theory at least, it could block the absorption of the fat-soluble vitamins (vitamins A, D, E and K) as well as the essential fatty acids (the “good” fats, like omega-3 and omega-6). So be sure to take a vitamin supplement at least an hour or so before the chitosan.
Cautions
Don’t take chitosan if you have an allergy to shellfish.
Chitosan doesn’t get absorbed into the bloodstream, which means it’s largely free of the side effects that so many people experience with numerous prescription (and nonprescription) weight-loss medications and supplements.
Because no extensive safety studies have been done, women who are pregnant or breast-feeding and children under age 14 should avoid chitosan. Ailments Dosage Weight Loss 1,500 mg once a day with a high-fat meal
Be well,
David Edelberg, MD