Chitosan

Chitosan is a form of fiber chemically processed from crustacean shells. Like other forms of fiber such as oat bran, Chitosan is not well digested by the human body. As it passes through the digestive tract, it seems to have an ability to bond with ingested fat and carry it out in the stool. For this reason, it has been tried as an agent for lowering cholesterol and reducing weight. In addition, Chitosan has been tried as a treatment for kidney failure and as an aid in wound healing. Note: We do not recommend the use of Chitosan in children or pregnant women due to concerns about possible growth retardation (see Safety Issues below).

Chitosan can be extracted from the shells of shrimp, crab, or lobster. It is also found in yeast and some fungi. Another inexpensive source of chitin is squid pens, a byproduct of squid processing; these are small, plastic-like, inedible pieces of squid that are removed prior to eating.

The standard dosage of Chitosan is 3 to 6 g per day, to be taken with food. Chitosan can deplete the body of certain minerals (see Safety Issues below). For this reason, when using Chitosan it may be helpful to take supplemental calcium, vitamin D, selenium, magnesium, and other minerals. Also, according to a preliminary study in rats, taking vitamin C along with Chitosan might provide additional benefit in lowering cholesterol.

Chitosan may make it harder for the body to absorb fat. One study suggests that use of Chitosan may aid in weight loss, although two shorter, smaller trials did not. The difference in outcome may lie in the type of Chitosan product used. The evidence is also mixed on whether it can lower cholesterol levels. Chitosan may be helpful in kidney failure. In this case, it is thought to work by binding with toxins in the digestive tract and causing them to be excreted. Studies in dogs have found that topically applied Chitosan can help heal wounds. This effect might be due to stimulation of new tissue growth; in addition, topical Chitosan appears to kill bacteria such as Streptococcus and yeast such as Candida albicans, which may also contribute to wound healing. Highly preliminary evidence suggests that oral chitosan may inhibit the expected rise in blood pressure after a high-salt meal. It has also been suggested that Chitosan can stimulate the immune system and help fight tumors, but there is no real evidence as yet that it works in these ways. Animal studies suggest that some forms of chitosan may help to prevent bone loss; however, because Chitosan also interferes with mineral absorption, the net effect in humans might actually be to increase bone loss (see Safety Issues below).

Weight Loss An 8-week double-blind placebo-controlled trial of 59 overweight individuals evaluated the effects of Chitosan taken at a dose of 1.5 g prior to each of the two biggest meals of the day. No special diets were assigned. The results showed that, on average, participants in the placebo group gained over 3 pounds over the course of the study, while those taking Chitosan lost more than 2 pounds. In contrast, an 8-week double-blind placebo-controlled trial of 51 women found that use of Chitosan at a dose of 1,200 mg twice daily failed to cause any weight loss. Similarly, in a 28-day double-blind trial of 30 overweight individuals, Chitosan taken at a dose of 1 g twice daily did not induce weight loss. High Cholesterol Preliminary human and animal studies found evidence that Chitosan can reduce cholesterol levels. For example, an 8-week double-blind placebo-controlled trial of 51 women found that use of Chitosan at a dose of 1,200 mg twice daily significantly reduced LDL (bad) cholesterol as compared to placebo. However, a 4-month double-blind placebo-controlled trial of 88 individuals found no benefit with 1,000 mg 3 times daily of a different chitosan product. Kidney Failure Individuals with kidney failure experience numerous health problems, including anemia, fatigue, and loss of appetite. In one unblinded study, researchers tested Chitosan supplements in 80 people with kidney failure receiving ongoing hemodialysis treatment. Half the participants were given 45-mg tablets for a total of about 1,500 mg of chitosan daily for 12 weeks; the other half were not given a supplement. Those in the treatment group showed a significant decrease in urea and creatinine levels. Further, they had a rise in hemoglobin levels and reported improved overall strength, appetite, and sleep as well.

There is significant evidence that long-term, high-dose Chitosan supplementation can result in malabsorption of some crucial vitamins and minerals including calcium, magnesium, selenium, and vitamins A, D, E, and K.In turn, this appears to lead to a risk of osteoporosis in adults and growth retardation in children. For this reason, adults taking Chitosan should also take supplemental vitamins and minerals, making especially sure to get enough vitamin D, calcium, and magnesium. Another possible risk of long-term ingestion of high doses of Chitosan is that it could change the intestinal flora and allow the growth of unhealthful bacteria. Pregnant or nursing women and young children should probably avoid Chitosan altogether.