Eating red onions may help to fight cancer, new research suggests.

The tasty vegetable, commonly used in Mediterranean cuisine, is full of powerful compounds that help to kill tumours.

One type known as anthocyanins, which are responsible for its dark colouring, are believed in inhibit the spread of the disease.

While a flavonoid called quercetin has the same effects by shrinking the size of cancerous masses, experts say.

But any type of onion, regardless of its colour, may help to destroy cancer, Canadian scientists claim.

The humble vegetable, commonly used in Mediterranean cuisine, is full of powerful compounds that help to kill tumours

'Onions are excellent at killing cancer'

Study author Abdulmonem Murayyan, of the University of Guelph, said: 'We found onions are excellent at killing cancer cells.

'Onions activate pathways that encourage cancer cells to undergo cell death.

'They promote an unfavourable environment for cancer cells and they disrupt communication between cancer cells, which inhibits growth.

'It makes sense that the red onions, which are darkest in colour, would have the most cancer-fighting power.'

How was the study carried out?

OTHER BENEFITS OF THE RED ONION Previous research has suggested that consuming red onion, which is sweeter than the white variety, could also help to prevent heart disease. Scientists in Hong Kong found that the vegetable works to remove bad cholesterol from the body, which can cause heart attacks and strokes. At the same time red onions retain the body's good cholesterol, which help protect against heart disease, they said in 2010. Numerous studies, including one at Cornell University over a decade ago, have also shown a link between onions and cancer. Some parts of the world where onion consumption is high have even been shown to have much lower cancer rates. Advertisement

For the new study, the researchers placed colon cancer cells in direct contact with quercetin extracted from five different onion varieties.

The Ruby Ring onion was found to be the most potent, according to the findings in Food Research International.

During recent studies, they also determined that onions are effective at killing breast cancer cells.

Commenting on the study, Dr Justine Alford, Cancer Research UK's senior science information officer, was wary of the findings.

She told MailOnline: 'The researchers found that extracts from certain types of onions could kill bowel cancer cells in a lab, but that doesn’t mean the same would happen in a person’s body which is much more complex.

'If scientists can tease out which molecules in onions have these apparently beneficial effects, then perhaps they could be investigated as a potential drug in the future.'

Human trials expected soon

The scientists are now aiming to test the vegetable's cancer-fighting properties in human trial in the coming years.

Onions are known to contain one of the highest concentrations of quercetin in the vegetable world.

This compound is believed to have the power of stealing iron from cancer cells, which they use to grow.

Quercetin's sneaky tactic can thus stop the disease from spreading across the body, experts have previously said.

The vegetables also have high amounts of anthocyanin, which the researchers found boost the properties of quercetin.

But on its own, anthocyanin also displays the same cancer-fighting properties, Ohio State University researchers previously found.