Shark cartilage is promoted as an alternative cancer treatment but there is no evidence that it works.
Shark cartilage is taken from spiny dogfish sharks and hammerhead sharks. It is made into a powder or liquid which you can buy as a food or dietary supplement.
Brand names for shark cartilage include:
Several years ago, a doctor published two books that claimed that sharks don’t get cancer and that shark cartilage could cure cancer. This is not true and sharks can get cancer. But many people with cancer still believe that shark cartilage may control their cancer or cure them, even though there is no scientific evidence for this.
Some people use shark cartilage as an alternative cancer therapy. This means that they use it instead of conventional cancer treatment such as chemotherapy or radiotherapy.
This can be very harmful to your health and we do not recommend that you do this.
How you have it
Shark cartilage comes in various forms. The most common type is capsules that you swallow.
You can also take it as:
- a powder or liquid that you swallow
- an enema (a liquid into the back passage)
- an injection under the skin
Most researchers agree that the protein molecules in shark cartilage powders are too big for the digestive system to absorb. So shark cartilage that you swallow is not likely to be absorbed into the body.
In the UK, shark cartilage is sold as a food supplement and not a drug. You can buy it over the counter in many health food shops. The USA’s Federal Trade Commission found that many over the counter products don’t actually contain much shark cartilage. Unfortunately, we don’t know how much shark cartilage is in the products available in the UK.
There is no scientifically proven recommended dose of shark cartilage. Some commercial suppliers suggest 70 grams per day. But shark cartilage contains calcium salts, and some doctors are worried this would mean taking in too much calcium. This could cause serious health problems.
Possible side effects
We know from research that shark cartilage can often cause changes in the way you taste things.
Other rare side effects include:
- feeling and being sick
- swelling of the hands and feet due to fluid build up
- low blood pressure
- high blood calcium levels
- loss of appetite
- change in blood sugar levels
These effects can be serious. In research studies, one person with diabetes had low blood sugar levels. Another had liver problems.
Doctors recommend that people with liver disease should not take shark cartilage.
Research into shark cartilage in people with cancer
Researchers have been interested in cartilage as a potential treatment for cancer because cartilage doesn’t contain any blood vessels. Cancers develop blood vessels to supply them with food and oxygen and help them to grow. Some laboratory studies have shown that certain compounds in shark cartilage can block the growth of blood vessels. So in theory this could slow down the growth of cancer cells or stop the cancer growing. But no research has shown that it can do this in humans.
In 1998, an American study tested shark cartilage in 60 patients with advanced cancer, when their treatment was no longer working. The study used the brand called Cartilage, which is a powder.
None of the patients showed a response to treatment with shark cartilage.
The study authors found that shark cartilage:
- didn’t help people with advanced cancer
- didn’t improve quality of life for people in the study
A highly purified extract of shark cartilage called Neovastat (AE-941) was tested in a clinical trial in America in 2007 and reported in 2010. Neovastat was given alongside chemotherapy and radiotherapy to people with advanced lung cancer. Everyone in the trial had chemotherapy and radiotherapy. Half the patients also had treatment with Neovastat. The other patients had a dummy pill (a placebo). The study showed that Neovastat gave few side effects and was safe to take but did not help people to live longer.
In May 2005, The United States National Centre for Complementary and Alternative Medicine (NCCAM) reported on a trial using a brand of shark cartilage called BeneFin. 88 patients with advanced breast or bowel cancer had either standard care or standard care plus Benefin. The study showed that shark cartilage did not improve survival or quality of life.
How much shark cartilage costs
Shark cartilage can be quite expensive. Capsules sold over the internet can cost about £20 for a box of 100 capsules.
Depending on who you buy it from, the recommended dose is between 3 and 12 capsules, 3 times a day. At the highest dose, £20 worth would last less than 3 days. Before you start taking it, it is important to consider the ongoing cost.
A word of caution
We do not recommend using alternative therapies such as shark cartilage. This is because there is no scientific or medical evidence to prove that it can treat or cure cancer.
Stopping your conventional cancer treatment to use unproven alternative therapies can be very harmful to your health. Talk to your specialist if you are thinking of taking shark cartilage alongside your cancer treatment. This way, your specialist team will have the full picture about your care and treatment.
Many websites advertise or promote shark cartilage as a cancer treatment. But no reputable scientific cancer organisations support them.
Be very cautious about believing information you read on the internet. Because there isn’t any regulation, people can use the internet to make false claims. Remember that anyone can write information or advertise health treatments.
The Memorial Sloan-Kettering Cancer Centre is a leading cancer hospital and research centre in New York. Its Integrative Medicine service was founded in 1999.
It carries out research into the effectiveness of complementary therapies for cancer.
The website has information about many types of herbs and dietary supplements. It also evaluates alternative or unproven cancer therapies.
The American Cancer Society has information about complementary and alternative therapies. Not all the information on the website is relevant for a UK audience.