Natural Products from the Sea: Ethnopharmacology, Nutrition and Conservation

Townsend Letter for Doctors and Patients, Feb, 2001 by Tim Batchelder

Chitosan has the unique ability to dissolve and bind fats and cholesterol in the stomach. Because chitosan is mostly indigestible, it can then prevent these lipids from being absorbed in the digestive tract. This can ultimately promote safe weight-loss and a reduction in cholesterol levels. Chitin and chitosan are also now being taken like acidophilus, FOS, and other supplements to speed the transit of foods through the digestive system and to promote the growth of beneficial live bacteria in the intestines. They can thereby improve digestion, cleanse the colon, and prevent diarrhea and constipation. More speculatively, chitin and chitosan may protect the liver, prevent or reduce tumors, heal ulcers, regulate blood pressure, and boost immune response. Chitin and chitosan have numerous industrial uses, in wastewater treatment; surgical sutures, wound dressings, and other medical applications; as a fertilizer and in animal feed; and in moisturizers, bath lotions, and other body care products.

Japanese researchers found that four weeks of chitosan supplementation reduced total blood cholesterol and caused a number of other beneficial effects on patients with kidney failure. (Jing, 1997) Chinese researchers recently confirmed antioxidant properties in chitin and chitosan compounds. Another recent study determined that a biological dressing made from chitosan was comfortable and efficient, and promoted the process of healing. (Drenda 1997)

Chitosan's primary mechanism of action is well established. It is known to differ from other polysaccharides in that it has a strong positive charge that lets it chemically bond with certain compounds, especially fats and cholesterol. Other mechanisms of action in the body are still being investigated. The ability to bond with fats and other substances is also the reason for many of chitin and chitosan's industrial uses. For example, spread on water chitin absorbs grease and other potentially toxic substances, which is why it is prominent in wastewater treatment processes.

Small amounts of chitin are found in mushrooms (where the substance was first identified in 1811) and yeast. The chitin and chitosan used to make nutritional supplements are derived from sources like crab shells and lobster shells, that are not eaten as foods. The most popular products are capsules and tablets ranging in size from 500 to 1,000 mg.

Chitin and chitosan are nontoxic and free of side effects, although they share the same precautions for safe use that apply to other types of fiber. Thus, to prevent intestinal blockage they should always be taken with plenty of water. Also, these supplements can bind with fat-based vitamins, such as vitamin E, and certain drugs, thus reducing these substances' absorption and effectiveness.

Shark Cartilage

Cartilage is a tough, elastic tissue found in the joints and other parts of the bodies of various organisms, including sharks and cows (bovine cartilage). Cartilage has a complex chemical makeup, including calcium, protein substances, carbohydrate mucopolysaccharides such as chondroitin, and collagen. Sharks are one of the prime natural sources of cartilage because their skeletons are made entirely of cartilage rather than bone.