What turmeric is
Turmeric is a spice that is often used as a food flavouring in Asian dishes. It belongs to the ginger family. It is also known as Indian saffron, jiang huang, haridra, haldi, as the major ingredient of curry powder 2, and as a bright yellow orange food colouring agent (E100).
Turmeric grows in many Asian countries such as India. It has been used for many years in some herbal remedies. The main active ingredient is curcumin or diferuloyl methane.
Currently there is no research evidence to show that turmeric or curcumin can prevent or treat cancer but early trials have shown some promising results.
Research into preventing cancer
A phase I clinical trial looked at giving curcumin to 25 patients with pre cancerous changes in different organs. This study seemed to show that curcumin could stop the precancerous changes becoming cancer.
Research has also shown that there are low rates of certain types of cancer in countries where people eat curcumin at levels of about 100 to 200 mg a day over long periods of time.
Research into treating cancer
A number of laboratory studies on cancer cells have shown that curcumin does have anticancer effects. It seems to be able to kill cancer cells and prevent more from growing. It has the best effects on breast cancer, bowel cancer, stomach cancer and skin cancer cells.
A 2013 international laboratory study looked at the effects of a combined treatment with curcumin and chemotherapy on bowel cancer cells. The researchers concluded that the combined treatment might be better than chemotherapy alone.
A 2007 American study in mice seemed to show that curcumin helped to stop the spread of breast cancer cells to other parts of the body.
Doctors think that curcumin stays in the digestive system and is absorbed by the cells in the bowel. To find out more, a small study in the UK looked at how curcumin is absorbed from the human gut into liver cells. This study looked at how much of the curcumin is absorbed into both cancer cells and normal cells. This was a very small study of people with bowel cancer that had spread to the liver. They were given curcumin for 7 days before surgery.
During the surgery doctors removed liver tissue and they then then measured the levels of curcumin in the tissue. The results showed that the level of curcumin absorbed into the liver was not high enough to have any anticancer effect. The researchers suggested that future clinical trials of curcumin should focus on preventing bowel tumours. Several studies have shown that curcumin taken as capsules does get absorbed by the gut and is present in the blood. But the amount in the blood is small.
A American phase 2 study reported in 2008. 25 patients had curcumin treatment and 21 had tumours that could be measured. In 2 patients their tumours shrank or remained stable. In some patients their levels of particular immune system chemicals that destroy cancer cells went up. But the researchers found that blood levels of curcumin were very low because it is not well absorbed from the gut. Scientists have since developed injectable, fat soluble forms of curcumin which may improve the results.
These studies look promising but we need to do more clinical trials in humans before we will know if curcumin has any potential to treat cancer in people.
A trial is currently under way in Puerto Rico to find out whether curcumin can shrink precancerous growths in patients with a genetic disorder that greatly increases their risk of bowel cancer.