Sharks are finally getting a warm welcome, thanks to a tough, rubbery material in their skeletons. Though myriad claims are made for shark cartilage – most spectacularly that it cures cancer – its actual effect on disease remains uncertain.
What it is?
Bone forms the framework of the human body. cartilage does the same for sharks. This elastic substance, which is softer than bone but tough and fibrous, is found in people as well: in the nose, for example, and around the joints. In recent years, shark cartilage products have become popular worldwide as a much-hyped remedy for a variety of ills. Harvested from the head and fins, the cartilage is first cleaned and dried, and then ground into a fine powder.
There is considerable debate, however, about whether the supplement is effective. Solid evidence in support of its health benefits lags significantly behind the glowing testimonials. What's more, ecological concern is mounting because shark populations around the globe appear to be declining rapidly as a result of overfishing.
What it does?
Most researchers greet the claims made for shark cartilage – from curing cancer and AIDS to healing arthritis and herpes – with skepticism. Some believe that stomach acids digest shark cartilage, rendering oral supplements ineffective; others say that even if the body does absorb the cartilage, it has no demonstrable therapeutic benefits. If shark cartilage does contain healing ingredients, they are present, at best, only in very small amounts. Though a few promising studies have been conducted, additional research is needed to confirm – or disprove – the effectiveness of this controversial supplement.
Research dating back to the 1980s sparked interest in this supplement's greatest claim to fame: its supposed ability to combat cancer. Observing that sharks rarely get cancer, investigators began studying various substances from sharks and noted that shark cartilage blocks the growth of new blood vessels. Because blood-vessel growth is essential for tumours – providing them with an oxygen-rich blood supply that allows them to survive and grow – the researchers speculated that the cartilage might fight cancer. (Cancer therapies that inhibit blood vessel growth recently made news when two drugs that shrink tumours – called angiostatin and endostatin – were isolated in the laboratory.)
Other theories have been advanced for shark cartilage's supposed anti-cancer effects, and studies in test tubes and animals suggest that it may have some cancer-fighting benefits. But what works in the test tube or in animals is often a far cry from what works in people. Studies have generally failed to show any significant benefits to people with cancer, even when shark cartilage was given in very high doses. In fact, a leading maker of shark cartilage supplements in the US recently admitted that the substance is 'probably not effective' for cancer.
Shark cartilage may have anti-inflammatory properties, however, that make it useful for treating diseases such as rheumatoid arthritis and the skin ailment psoriasis. In one study, animals given a shark cartilage extract experienced less pain and inflammation from substances that irritate the skin.
Shark cartilage may also ease symptoms of osteoarthritis by facilitating the delivery of cartilage-building nutrients to the joints, thereby stimulating cartilage repair while reducing cartilage breakdown. (Most doctors, however, believe there are more effective remedies for this purpose, such as glucosamine.) Because of its possible immune-boosting effects, the supplement has also been proposed as a treatment for cold sores and other herpes infections.
- May help to fight cancer.
- May ease arthritic joint pain, reduce the skin lesions of psoriasis and help to heal cold sores.
- Because it may interfere with new blood vessel growth, shark cartilage should not be used by women who are pregnant or breast-feeding; by anyone who has suffered a heart attack or stroke; or by those who had had recent surgery.
- Reminder: If you have a medical condition, talk to your doctor before taking supplements.
How to take it?
For disorders such as arthritis: Dosages of about 2000 mg of shark cartilage three times a day are sometimes recommended.
For cancer: Practitioners sometimes recommend doses as high as 1000 mg per kilogram of body weight, which would mean 68000 mg for someone weighing 68 kg – a substantial expense for a supplement whose value has not been proved.
Guidelines for use:
Some researchers suggest taking the supplement on an empty stomach to minimize exposure to stomach acids that could destroy any active ingredients. Because of the large amounts recommended to treat cancer (in some cases the equivalent of more than 100 capsules a day), the powder form may be more convenient and less costly. However, those concerned about the fishy taste of many products may find tablets or capsules the best options.
Possible side effects
Even when taken in large amounts, shark cartilage does not seem to produce any toxic reactions.
- Many shark cartilage products contain few active ingredients because they're extensively diluted with binding agents and fillers. Read the labels carefully to see what you're getting.
- According to a recent Canadian study, shark cartilage helps to treat psoriasis, a condition that's marked by excessive inflammation and growth of new blood vessels in the skin. To mimic the disease, investigators applied a chemical irritant to the arms of nine healthy volunteers. When spread on the skin before the application of the irritant, an extract of shark cartilage effectively curtailed inflammation. In a follow-up study, the extract also soothed the rashes of people with psoriasis.
- Though shark cartilage is sometimes promoted for its cancer-fighting properties, the supplement appeared to have no effect in as recent study conducted by the Cancer Treatment Research Foundation in the US. Some 60 patients with breast, colon, lung, prostate and other advanced cancers took numerous spoonfuls of shark cartilage three times a day. Over 10 months, the supplement had no discernible effect on their tumours.
Did you know?
In Japan, shark's fin soup is believed to increase longevity.