Unlike other animals, the skeleton of sharks is composed almost entirely of cartilage. Shark cartilage contains many of the same compounds that make up human cartilage, including proteins, chondroitin sulfate, calcium, phosphorus, and hyaluronic acid. Shark cartilage supplements are derived from the skeletons of sharks that are caught for food purposes.
Shark cartilage is commonly taken in doses of 3,000 to 5,000 mg per day, and is generally well tolerated at this dosage range. Some people may experience nausea when taking larger doses. Although shark cartilage has no known toxicity, because of its high calcium content, daily intake should not exceed 50 grams.