Cartilage is a type of connective tissue in the body that has a tough, flexible matrix made of collagen, protein, and sugar. Cartilage is found in the nose and ears, as well as joints, including the knees, hips, shoulders, and fingers.

The cartilage used in supplements usually comes from either sharks or cows, called bovine cartilage. Shark cartilage was proposed as a treatment for cancer, based on the false idea that sharks do not get cancer (they do). In test tubes, cartilage seemed to stop new blood vessels from forming. Cancerous tumors need new blood vessels to keep growing, so researchers wondered if shark cartilage could shrink tumors. But so far, studies in people have not found any evidence that shark cartilage stops, prevents, or even slows the growth of cancerous tumors.

Cartilage has also been proposed as a treatment for osteoarthritis, which is the "wear and tear" arthritis that happens when cartilage in your joints breaks down. The idea is that taking shark or bovine cartilage, or a supplement called chondroitin, which is part of cartilage, will help your body repair or grow new cartilage in your joints. There is not any evidence that taking cartilage helps, but the story is a little more complicated when it comes to chondroitin.

Cartilage is sometimes suggested for the following health conditions:

Psoriasis

Preliminary studies suggest that extracts of shark cartilage may reduce inflammation and itching from psoriasis. Psoriasis is a skin disorder that shows up as raised, reddish-pink areas covered with silvery scales and red borders.

Osteoarthritis

Two substances that make up cartilage, glucosamine and chondroitin, have been studied for osteoarthritis (OA). A number of these studies suggest that chondroitin may help treat OA. In OA, cartilage in the joints breaks down, either because of injury or to normal wear and tear. OA is common as people get older. In some studies, chondroitin supplements have reduced the pain of OA. Not all studies are positive, though, and recent research has not shown any benefit from taking chondroitin. It is not clear why the studies have different findings, and experts disagree on whether chondroitin is helpful in treating OA.

So far studies have not shown conclusively that chondroitin helps repair or grow new cartilage, or stops cartilage from being further damaged. Chondroitin is often taken with glucosamine. Like chondroitin, glucosamine also has conflicting results.

Cancer

Although there is no scientific evidence that it works, shark cartilage has been widely used as an alternative treatment for cancer. Researchers wondered if cartilage could produce substances that stop new blood vessels from growing. Cancerous tumors rely on blood vessels to survive because blood provides oxygen and nutrients necessary for their growth. If cartilage could "starve" cancerous tumors of oxygen and nutrients, then researchers thought it might help treat cancer.

Several clinical studies have been done on cartilage as a treatment for cancer, but only a few have been published in scientific journals. None of these have found any benefit in using cartilage supplements for cancer, including breast, colon, lung, prostate, brain, and lymphoma. According to the National Cancer Institute (NCI), the evidence so far is inconclusive. The NCI halted its own research on cartilage supplements because the preparations were contaminated, and the Federal Trade Commission (FTC) has taken legal action against several companies selling cartilage products as a "cancer cure."

You cannot get cartilage from food. It is only available in supplements.

Cartilage is available in powdered form or in capsules that contain the powder. It is also available as a topical cream. Most cartilage supplements are made from bovine (cow) or shark sources.

Pediatric

Children under 18 should not take cartilage.

Adult

For adults 18 years and older: Doses of 200 to 2,000 mg per kilogram of body weight, 2 to 3 times a day, have been used. Ask your health care provider for the best dosage. It is possible that high doses of cartilage could mean you would get more calcium than is recommended.

Because of the potential for side effects and possible interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

Side effects may include nausea, vomiting, constipation, and change in taste.

Tell your doctor immediately if any of these serious side effects occur: weakness, tiredness, dizziness, unusual thirst or urination, shakiness, changes in mood, or mental symptoms.

Tell your provider immediately if any of these rare but serious side effects occur: symptoms of liver disease including yellowing of eyes or skin, severe stomach ache, persistent nausea, or dark urine.

Buy shark and bovine cartilage from a reputable manufacturer to reduce the risk of contamination. Check labels carefully, and buy only supplements that contain 100% pure shark cartilage.

There has been at least one case of hepatitis reported from taking shark cartilage.

Pregnant and breastfeeding women, children, and people recovering from surgery or a heart attack should not take cartilage supplements.

DO NOT use cartilage by itself to treat cancer. Cancer requires conventional medical treatment.

Shark cartilage products may contain high levels of calcium. People with kidney disease, abnormal heart rhythms, a tendency to form kidney stones, and those with cancers that raise calcium levels should not take cartilage.

Shark cartilage may lower blood sugar levels. People with diabetes should talk to their provider before taking cartilage, so their blood sugar levels can be monitored.

Acidic fruit juices, such as apple, grape, or cranberry, may reduce the amount of shark cartilage your body absorbs.

If you are being treated with any of the following medications, you should not use cartilage supplements without first talking to your health care provider.

Thiazide diuretics (water pills): Cartilage contains high amounts of calcium. Thiazide diuretics, such as hydrochlorothiazide, can raise calcium levels in the blood. Taking cartilage along with diuretics could lead to dangerously high levels of calcium.

Thyroid medication: Shark cartilage may interact with thyroid medications.

Calcium supplements: Taking shark cartilage along with calcium supplements may lead to high levels of calcium in the blood.

Diabetes medication: Shark cartilage may lower blood sugar levels, raising the risk of hypoglycemia or low blood sugar.

Antibiotics: Some antibiotics may interact with shark cartilage.

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