The foods full of cancer-fighting fibre (and you have most of them in your cupboard)

We’re used to hearing that a diet stuffed full of protein is key to our health. But in the process of cramming chicken breast and tinned tuna onto our plates, we’ve been overlooking a key micronutrient, says Hugh Hanley, director of personal training and nutrition for PureGym.

“Fibre is a crucial part of a balanced diet. It promotes gut health by giving your gut good material to feed on, which encourages regular bowel movement and prevents constipation,” Hanley says.

Even more importantly, a fibre-rich diet also reduces a person’s risk of bowel cancer, reveals new research from Stanford University. According to Prof Michael Snyder, a genetics professor who helped lead the research, it was found that there was a direct link between a high-fibre diet and changes in the function of certain genes in the body “that [have] anti-cancer effects” in our colons.

Other research indicates that fibre-rich diets can help to prevent bowel cancer by keeping stools moving through our systems, meaning that potential carcinogens spend less time within our bodies.

“When we have a slow digestive movement, we’re leaving toxins and unwanted products in the body for much longer than needed, which has been shown to contribute to bowel cancer risk,” says registered nutritionist Jenna Hope. “Ultra-processed foods tend to contain very little fibre, which is part of what makes them damaging to our health.”

While we should all be aiming to eat about 30g of fibre a day, the average person in Britain manages a measly 18g. Modern processed foods often lack fibre, but my grandparents had the right idea: old-fashioned foods like prunes, oats and lentils all contain reams of the stuff.

Here are 10 of the best high-fibre foods to add to your diet, and why we should all be piling our plates with it.

Oats

9.1g per 100g

Porridge is the breakfast of choice for at least one in 10 of us every day. If you’re looking to eat more fibre, there’s good reason to add yourself to that figure. “Oats are a very good source of insoluble fibre, which can’t be absorbed by your body so helps keep things moving through your digestive system,” Hope says.

On top of that, “oats contain a large amount of beta-glucans”, says Hope. “Eating 3g of betaglucans a day is shown to lower cholesterol levels, and there are around 3.6g of beta-glucans in 100g of oats.”

“This is a major reason why they’ve gained superfood status,” Hope adds. Steel-cut oats will contain more fibre and beta-glucans than rolled and instant oats, as they are less processed.

Garden peas

5.6g per 100g

Garden peas are the sidekick to many a weeknight dinner and the fibre in them gives you good reason to pile them up high on your plate.

Peas contain much less sugar than raspberries (see below) but almost as much fibre, and they are also higher in insoluble fibre, making them a better option for those looking to regulate their digestive systems.

As Hope says, “there’s no one pulse that should be highlighted as the only one you need to eat”. But adding these into your meals will provide a big fibre boost.

Prunes

7.9g per 100g

Everyone knows that prunes are jam-packed with fibre. Many of us keep a bag or tin in the back of the cupboard in case of constipation emergencies.

Like oats, prunes contain insoluble fibre, but they contain large amounts of soluble fibre too, “which will bind to some of the water in your digestive tract and help to bulk out your stools”, Hope says.

And while suddenly upping your fibre intake can cause uncomfortable bloating and gas, research indicates that prunes are easy for your system to tolerate following a long-term low-fibre diet. More reason to add them to your shopping basket each week.

Raspberries

6.8g per 100g

Of all berries, the raspberry is the king when it comes to fibre, containing more of it gram-for-gram than blueberries, blackberries, strawberries or cherries. They are also lower in sugar than many other berries.

A punnet “can make a great snack if you’re looking to eat more fibre but don’t have time to cook,” says Hanley, and their bright red colour indicates that they’re packed with cancer and inflammation-fighting antioxidants.

Black beans

10.3g per 100g

Any bean will be “a very good source of fibre”, says Hope, “and it’s important to have a variety of them in your diet, as they all contain different micronutrients”.

Chickpeas, cannellini beans and butterbeans are all high in fibre too, but “it’s good to stay away from beige foods as much as possible”, says Hanley. “Foods that come in a variety of colours are best for your health.”

Black beans, with a huge punch of fibre and dark skins rich in heart-healthy anthocyanins to boot, are a winner. Research shows that eating them regularly can even lower your blood pressure.

Popcorn

4g per 25g serving

Popcorn is a super-satisfying fibre-rich snack. A 25g serving of plain popcorn contains less than 120 calories, but more than an eighth of your recommended daily fibre intake.

That said, to feel the benefits of eating more popcorn, you really do have to buy a pack of kernels and pop it yourself at home.

“Some people think that buying a bag of microwave popcorn will be healthy, but those often contain just as much salt and sugar as a ready-popped bag,” says Hope. “You’d need to buy the kernels themselves and pop them in a pan on the hob.”

Almonds

5.3g per large handful

Almonds are the nut that’s highest in fibre, with nuts and seeds being “very high-fibre foods” in general, Hope says – and research shows that, like prunes, almonds can be worked into your diet quickly without upsetting your gut in the short-term.

What’s more, “research shows that your body actually won’t absorb the full amount of calories you’re consuming by eating almonds, as long as they’re whole rather than sliced or ground, because the amount of fibre found in them makes them less digestible”, Hope explains.

Chia seeds

4.8g per tablespoon

These days chia seeds are often the star ingredient in upmarket smoothies, puddings and breakfast bowls, but they can easily be added to a bowl of porridge or a slice of wholegrain toast with peanut butter.

“Chia seeds are excellent at absorbing excess water, so they really bulk up your stools. You can even add them to water, which is a great choice for people who struggle to stay hydrated,” Hope says.

That said, blending these seeds up in a smoothie “will break down some of that fibre, making it less useful to your digestive system”, Hope warns. But chia seeds are “still very beneficial” however you like to eat them.

Avocado

3.4g per 100g

Unlike the other ingredients on this list, avocados are a source of fibre that is also rich in healthy fats. This is a combination that is especially good for keeping us full throughout the day, research suggests.

“The kinds of fibre found in foods high in fat, protein and carbohydrates are all different, and different types of fibre feed different types of bacteria in your gut,” Hope explains. “This is part of why it’s so important to eat a diverse diet.”

Sweet potato

3g per 100g

With sweetness and a satisfying carb-y texture, it’s easy to get through a mountain of sweet potato mash, chips or wedges on the side of your plate, and your gut will thank you for doing so. Research shows that the fibre found in sweet potatoes is especially good for promoting the diversity of your gut microbiome.

It’s best to eat sweet potatoes with their skins however, “as this is where a lot of the fibre in a sweet potato is stored, with insoluble and soluble fibre there in good amounts”, Hope says. She suggests trying them baked instead of a normal jacket potato “as by frying them you can increase the amount of saturated and trans fats present”.

FAQs:

Can you ever have too much fibre?

In the short term, “adding a lot of fibre to your diet very quickly can cause bloating, gas and general discomfort, as well as actually worsening constipation,” says Hanley. While there’s no amount of fibre that would become dangerous to your health if regularly consumed, he adds: “I recommend that people increase their fibre intake gradually.”

This doesn’t mean rigorously tracking your food intake, “just bringing in a variety of different fibre sources over a couple of weeks”, he advises. “If you’re eating five different colours of fruit or vegetables one week, try making it seven or eight the next and your fibre intake will be increasing too.”

Should I take fibre supplements?

“You should always try to get your fibre from your meals if you can, rather than from bars or supplements,” Hanley says. “A fibre bar might add more fibre to your diet, but it’ll also be bringing in 15 to 20 other ingredients and more calories than you really need, too.”

That said, “fibre supplements can be helpful where people really are struggling to eat enough of it in their diets, and that’s when I’d suggest them”, Hanley adds.

Is there a best time of day to eat fibre?

There is no best time in the day to eat fibre, but incorporating it into each meal promotes feelings of fullness that can help keep you from snacking on unhealthy foods throughout the day.

How much fibre do I need?

Although NHS guidelines state that we should all be aiming to eat 30g of fibre a day, the exact amount you need depends on your age and gender.