Chitosan is particularly interested in the nutritional industry when it was introduced into the market in the 1990s. Health food supplement manufacturers suggested its potential as a nutritional adjunct for weight management. They emphasized favorable results from a few studies; they claimed that chitosan was a beneficial effect on weight loss, cholesterol, ulcers, osteoporosis and blood pressure. They hypothesized that the electrical charges that chitosan carries may bind to the negative charges on bile acids and fatty acids, resulting in the hypocholesterolemic (cholesterol lowering) effect. In addition to enhancing cholesterol excretion, this ionic bonding resulted in excretion of fat, along with its associated phospholipids, monoglycerides and other fatty acids.

Dosage
For reducing high cholesterol and improving anemia, physical strength, appetite, and sleep in people with renal failure who are undergoing hemodialysis: 1.35 grams of chitosan three times daily.

How much chitosan should a person take to be effective to prevent the fat absorption?
If a person ingests two pounds of New York Steak, will 1 g of chitosan be enough? As this is a swelling polymer, definitely, we don't want to take too much of chiton to block our GI tract. This article is not suggesting that chitosan supplements have no benefit on weight management. In fact, a recent review article assessed results of 14 randomized controlled trials that included 1,131 overweight or obese adults and the authors found that those who received chitosan had an average weight loss of almost 4 pounds more than those on placebo in the short term, and their cholesterol and blood pressure levels also decreased more than those in the placebo group. And, they didn't observe any side-effects in the group taking chitosan.

Possible Side-Effects / Precautions / Possible Interactions
Chitosan is possibly safe for most people when taken by mouth short-term (up to six months) or applied to the skin. When taken by mouth, it might cause mild stomach upset, constipation, or gas.

Special Precautions & Warnings
Pregnancy and breast-feeding: Not enough is known about the use of chitosan during pregnancy and breast-feeding. Stay on the safe side and avoid use.
Shellfish allergy: Chitosan is taken from the outer skeleton of shellfish. There is a concern that people with allergies to shellfish might also be allergic to chitosan. However, people who are allergic to shellfish are allergic to the meat, not the shell. So some experts believe that chitosan may not be a problem for people with shellfish allergy.

Caution: Do not use if abdominal pain, nausea, or vomiting is present, unless directed by your physician. Those allergic to shellfish should not use this product.
Chitosan supplements should not be consumed within two hours of taking the fat-soluble vitamin A, D, E and K, carotenoids (e.g. lycopene, lutein), flavonoids (e.g. genistein, quercetin, ipriflavone) or prescription medication.