Experts are suggesting too much meat and microplastics in food could be behind the cause of a massive surge in bowel cancer in young Australians.

It’s the deadliest cancer for Aussies aged 25-44, but they are too young for free screening even after the government lowered the age cut-off to 45 last year.

The number of Aussies below the age of 40 who are diagnosed with bowel cancer has more than doubled since 2000.

The age group from 15 to 24 has seen a particular spike, going up by 266 per cent over three decades.

While the exact cause remains unknown, experts have several theories.

‘Some theories are it could well be related to accelerated ageing in a younger population,’ Bowel Cancer Australia CEO Julien Wiggins told 10 News.

‘It could be to do with gut bacteria in the microbiome, for example, and even microplastics.’

Colorectal surgeon Dr De Lacavalerie warned that the majority of young people she operates on have no family history of bowel cancer.

She said excessive meat consumption could be a major factor contributing to the rise in bowel cancer cases. 

‘We are eating way too much meat in Australia, and in particular New Zealand, which has the highest incidence in the world of bowel cancer,’ Dr De Lacavalerie said.

A lack of fibre in the diet is also a main driver of bowel cancer, according to experts.

‘A low fibre diet slows down the gut,’ oncologist Tobias Arkenau said.

‘If toxins don’t move out of the organ it can sit there and eventually cause inflammation and possibly a higher risk of bowel cancer.’ 

Fibre, which is the part of plant-based foods that can’t be completely broken down by our guts, helps to regulate bowel movements.

Dietary guidelines recommend eating 30g of fibre per day – it is found in leafy green vegetables, pulses and wholegrains.

Diets high in the nutrient have been found to significantly reduce the risk of bowel cancer, because regular bowel movements help to expel harmful chemicals from the body. 

Bowel cancer symptoms include changes in bowel movements such as consistent and new diarrhoea or constipation, needing or feeling the need to poo more or less frequently, and blood in the stool.

Stomach pain, a lump in the stomach, bloating, unexpected weight-loss, and fatigue are among other common signs.

Though the disease is increasing among young people, their symptoms are often dismissed.

When Beth Tudehope, 38, went to the doctor with stomach pain, it was initially difficult to pinpoint the cause.

‘They gave her some medication and said go home and hopefully that (would be the end of it) – and she said no, I’m just not right,’ her father, Peter Tudehope, told 10 News.

‘This is not an old person’s disease – this is a young person’s disease.’

Further testing revealed that Beth had stage four bowel cancer. She died of the disease at just 38 years old.

Another Aussie, Tracey Robinson, 38, recently discovered she had stage four bowel cancer after ending up in the emergency department with abdominal pain.

A GoFundMe has been set up to help Ms Robinson and her husband cover the costs of her treatment.

She said there can also be a reluctant among potential sufferers to come forward with their symptoms.

‘You don’t want to sit and talk about your bowel movements or that, so it is something that you don’t really want to advertise or want to bring up.’

Doctors have told her that surgery to remove the tumour in her upper colon isn’t an option so she is taking immunotherapy drugs in a bid to beat the cancer, which has spread to her liver. 

Australians can order a bowel screening test via the Bowel Cancer Australia website or visiting a local chemist.