Shark cartilage and cancer

Shark cartilage is a food or dietary supplement. It is sometimes used by people as an alternative cancer treatment.

There is not enough reliable evidence that it works as a cure for cancer. 

Summary

• Shark cartilage comes from spiny dogfish sharks and hammerhead sharks.

• Claims that shark cartilage can treat cancer are not backed up by research.

• Using shark cartilage as an alternative to conventional cancer treatment can be very harmful to your health.

What is shark cartilage?

Cartilage is a tough, flexible tissue found in the body and has no blood supply. Shark cartilage comes from spiny dogfish sharks and hammerhead sharks. It is available as a powder or liquid which you can buy as a food or dietary supplement. There are several different brand names for shark cartilage. 

It was once thought that sharks can't get cancer. But this is not true. Sharks can get cancer. 

There is no scientific evidence that shark cartilage can control or cure cancer. Some people use shark cartilage as an alternative cancer therapy. This means that they use it instead of conventional cancer treatment such as chemotherapy, targeted drugs 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.

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
• itching
• diarrhoea
• constipation
• indigestion
• dizziness
• swelling of the hands and feet due to fluid build up
• tiredness
• low blood pressure
• high blood calcium levels
• loss of appetite
• change in blood sugar levels

These effects can be serious. Doctors recommend that people with liver disease should not take shark cartilage.

Research into shark cartilage as a cancer treatment

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.

A highly purified extract of shark cartilage called Neovastat (AE-941) was tested in a clinical trial in America. They gave Neovastat 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.

How much it costs

Shark cartilage can be quite expensive. Capsules sold over the internet can cost from around £20 for a box of 100 capsules.

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.