The 30g diet hack that ‘PREVENTS deadly bowel cancer’

October 23, 2025

IT’S the second deadliest cancer in the UK, claiming the lives of more than 16,000 every year.

And doctors are worried, as cases of bowel cancer continue to surge in the under-50s. But what can be done about it? While science delves into what’s behind the rise, there is one simple diet hack, that could prevent almost one in THREE cases – yet most Brits don’t have a clue.

According to data from the Government’s Office of Health Improvement and Disparities (OHID), 96 per cent of adults don’t meet the government recommendation of 30g a day.

It means they are also missing out on benefits such as weight loss and diabetes prevention.

We’re talking about fibre – no, it’s not glamorous or sexy. But it’s an unsung hero when it comes to your health.

Most of us know fibre as the food that helps you ‘go’. It is always recommended as the first tool to alleviate constipation.

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And yes, you get it in bran flakes and other cardboard-type foods, such as seeded crackers.

But there is much, much more to it, according to Susan Short, a Public Health Nutritionist, Specialist Dietitian and British Dietetic Association spokesperson.

“There are many benefits to fibre in the diet,” she tells Sun Health.

“It is essential for your gut to work normally. It increases good bacteria, which supports your immunity against inflammatory disorders and allergies, and it seems to reduce the risk of chronic diseases such as cardiovascular disease, type 2 diabetes and bowel cancer.”

There are 44,100 new cases of bowel cancer every year in the UK, and while most of these are in people in their 80s, young people get it too.

Around 2,300 people are diagnosed before the age of 50 in the UK each year – Dame Deborah James, a fearless bowel cancer campaigner who died in June 2022, aged 40, was among them.

The Sun columnist died five-and-a-half years after she was told she had incurable bowel cancer in 2016, aged 35, and relentlessly advocated for better awareness of the disease.

Rates of bowel cancer in those aged between 25 and 49 have increased by 51 per cent in the past 30 years.

But there’s one hack most of us are missing.

Cancer Research UK says eating lots of fibre reduces your risk of bowel cancer.

Shockingly, a low-fibre diet causes 28 in 100 (28 per cent) of bowel cancer cases.

That means 12,300 cases could be prevented every year, in theory, if fibre was better prioritised in the diet.

“A high fibre diet can be perceived to just be salad and brown bread but far from it,” says Susan.

“Fibre can be found in so many foods.

“With some planning, fibre is easily increased in your diet to meet the recommendations of 30g a day.

“However, due to a high level of ultra-processed, convenience foods consumed in the UK’s diet as a whole, many only consume about 18g a day at the most.

“Many struggle to eat more than two to three portions of fruit and vegetables a day or choose white, low fibre versions of cereals, bread, pasta and rice than the wholegrain versions.”

Fibre has become better-known as ‘nature’s Ozempic’ in the current fat jab era.

It triggers the production of the hormone GLP-1, which weight jabs like Ozempic, Mounjaro and Wegovy, mimic. GLP-1 helps us to feel full.

But Susan says fibre is a better tool for weight loss than weight loss jabs like Wegovy and Mounjaro.

“A high fibre diet is a more sustainable option as it promotes a long-term change that will improve your nutritional intake and benefit your health both now and in the future,” she says.

FIBRE 101

It’s time to rethink fibre, not as a boring afterthought but as a priority.

Symptoms of a low-fibre diet may include constipation, fewer bowel movements and bloating.

Here, we take a look at the types of fibre you need in your diet and how they correlate to a lower risk of bowel cancer.

Plus, exactly how you can eat more of each type every day.

INSOLUBLE FIBRE: The stool saviour

Fibre can help you go to the toilet, particularly insoluble fibre.

“Insoluble fibre will encourage regular bowel movements and if constipated, we would encourage an increase in this type of fibre,” says Susan.

“The word insoluble means it can’t be digested in your small intestine.

“Instead, it is completely or partially broken down (fermented) by bacteria in your large intestine, so it helps to keep bowels regular and the gut healthy.”

Keeping regular bowel movements – and a faster transit time – means harmful chemicals in poo spend less time in the bowel, Cancer Research UK says.

A normal stool should be sausage-like and either smooth or with cracks and depending on the normal bowel habits of the individual, should be passed once every one to three days

Susan Short, a Public Health Nutritionist and BDA spokesperson

Potential carcinogens (cancer-causing substances) in the faeces spend less time in contact with the lining of the colon.

The charity adds that wholegrains may be especially good for preventing bowel cancer, according to research.

Susan also says the types of foods that contain insoluble fibre – like the skins of fruit and vegetables and wholegrains, are nutritious and support a healthy gut microbiome.

“The good bacteria in your gut will thank you for this,” she says.

So how many number twos are healthy?

Everyone is different. But the golden number, researchers from the Institute for Systems Biology at the University of Chicago suggest, is at least once or twice a day, or between seven and 14 times per week.

Susan says the Bristol stool scale is useful for assessing whether your stools are healthy in frequency and appearance.

“A normal stool should be a type 3 or 4, sausage-like and either smooth or with cracks and depending on the normal bowel habits of the individual, should be passed once every one to three days,” she says.

“Small, harder lumps can be indicative of constipation and soft blobs or more liquid consistency would be diarrhoea.

“Also, those with conditions such as IBS, may find fibre in larger amounts causes bloating, gas and diarrhoea.”

Generally, to increase insoluble fibre, Susan suggests going slow: “Increasing gradually can help avoid gut symptoms such as bloating and gas, and allows the gut to adjust to the higher intake.”