How to know when to take fibre supplements

Fibre is a nutrition superstar, but most of us aren’t getting enough. Could supplements be the quick fix, and which are the best to buy?

It bulks out meals, is the cornerstone of good gut health and can protect our heart and brain. But when it comes to fibre, we’re not getting enough of it.
We should be eating at least 30g a day, with plant-based foods acting as the richest sources – think a portion of broccoli (2g), raspberries (3g), brown rice (4g), lentils (5g) or chickpeas (8g). However, average daily intake in the UK has been stubbornly stuck at just 18g for more than a decade.
Naturally, it seems that a supplement could offer a quick fix to the problem, potentially offering a myriad of benefits from outstanding gut health, to healthier cholesterol levels and weight loss. 
The trendy nutrition company Zoe recently launched their own fibre supplement, which it says boosts energy and reduces hunger pangs, while a study earlier this year suggested that a daily fibre supplement can improve brain function within weeks. 
But can fibre supplements really deliver the same benefits as a fibre-rich diet?.
Fibre is a carbohydrate found in all plant-based foods. However, unlike other carbohydrates that are easily broken down by human digestive enzymes, fibre isn’t. 
“Instead, it travels down your gut, passing through your small and large intestine, where it is fermented by trillions of microbes (the gut microbiome),” explains Sammie Gill, a registered dietitian and a British Dietetic Association (BDA) spokesperson.
During this process, gut microbes release health-promoting compounds such as short-chain fatty acids and neurotransmitters.
“Some of these compounds enter the bloodstream, whilst others act on the nervous system or immune system (of which 70 per cent sits along the gut),” she says. Ultimately, this benefits organs including the brain and the heart.
“Although the brain and the gut were long thought to be separate entities, we now know they are intrinsically connected – they are in constant communication with one another,” says Gill. “Fibre helps facilitate that communication.”
When fermentable fibre such as prebiotics or resistant starch are broken down by gut microbes, they release short-chain fatty acids and neurotransmitters which can travel outside of the gut and interact with the brain.
Studies have linked these fibres with improved brain health. Researchers at King’s College London, who studied 36 sets of twins aged over 60, found that those who took a daily prebiotic fibre supplement saw their brain function improve within three months.
Meanwhile, a major 2017 study found that one in three patients with depression who followed a Mediterranean-style diet for three months (containing 50g of fibre daily), recovered from the condition, compared to just eight per cent in the control group.
“In addition, short-chain fatty acids are thought to play a key role in dampening neuroinflammation (inflammation within the brain and spinal cord) which is linked to mental health disorders such as depression,” Gill adds.
Fibre speeds up gut transit time (the time it takes food to pass through the digestive system) by bulking out stool and improving its consistency, making them softer and easier to pass, notes Gill. Studies show faster transit time is linked with better health and less belly fat.
Additionally, fermentable fibres such as inulin (found in onion, leeks, wheat, oats and pulses such as lentils, beans and chickpeas) provide a food for gut bacteria, increasing their number, explains Clare Thornton-Wood, a registered dietitian and BDA spokesperson.
These fibres then produce short-chain-fatty-acids such as acetate, propionate and butyrate, which have been linked to reduced gut inflammation and a stronger gut lining, she says.
Eating plenty of fibre has also been shown to protect against bowel cancer. This is thought to be down to gut microbes releasing butyrate, which helps the cells in the bowel stay healthy, meaning tumours are less likely to develop, according to Cancer Research UK.
“Nourishing your gut microbiome is fundamental for short and long-term physical and mental health. Collectively, fibre keeps the gut functioning at its best,” Gill says.
“Beta-glucan is a particular type of fibre found in foods such as oats (also smaller amounts in barley and wheat) which has been shown in studies to reduce cholesterol levels,” says Thornton-Wood. High cholesterol – when fatty substances build up in the blood – can block blood vessels and increase the risk of heart attacks and strokes.
Additionally, animal studies have shown that short-chain fatty acids produced in the gut can improve blood pressure, notes Gill. As with high cholesterol, high blood pressure can lead to heart attacks and strokes, as well as blood clots.
High-fibre foods keep us feeling fuller for longer, so can help maintain a healthy weight and reduce the risk of obesity, which can bring complications for the heart, adds Thornton-Wood. 
“A fibre supplement can be beneficial in specific scenarios,” says Gill. “For example, it can help with constipation or diarrhoea. However, it’s unnecessary for everyone to take one.”
“It is always better to get your fibre from dietary sources as this will provide you with a range of nutrients rather than just fibre,” explains Thornton-Wood.
“For instance, a slice of seeded bread, in addition to fibre, provides omega-3, vitamins such as thiamine and minerals such as iron and calcium, plus protein and carbohydrates. Meanwhile, supplements will generally only contain one type of fibre.”
This means fibre supplements may only offer limited benefit for our gut health, Gill says. “A diversity of fibres ensures your gut microbes are well-fed and have all they need to function optimally. You’re getting far more bang for your nutritional buck with fibre-filled foods versus fibre supplements.”
“It’s important to be prescriptive and choose the specific fibre supplement that has been shown to be effective for the symptoms you’re wishing to target,” says Gill.
For constipation, psyllium husk, which comes as capsules or powder, can help. It is a source of fibre that has been shown to soften hard stools and increase stool volume, she says. 
The supplement, made from the outer coating of psyllium seeds, can also help with diarrhoea, as it slows gut transit time and firm up stools, Gill says.
Those looking to increase their fibre intake could incorporate supplements such as rye flakes or wheat bran into their breakfast or baking, she recommends. “Remember that fibre supplements are there to supplement your diet, not to replace your diet,” Gill adds.
Thornton-Wood advises talking to a dietitian, pharmacist or GP before taking a supplement. They will check if it is suitable and identify any underlying conditions that may be causing you to think you need a fibre supplement, she says. They can also flag if the supplement may interact with medication.
“If one is needed I would recommend taking for as short a time as possible and swapping back over to food sources of fibre as soon as you can,” Thornton-Wood says.
“Be aware that any increase in fibre can initially cause wind and bloating, though this is less likely if you increase your fibre intake gradually,” she adds.
“It absorbs water making stools softer to pass,” says Thornton-Wood. “It is also a prebiotic important as a fuel source for probiotics and therefore gut bacteria.” It comes in capsules or powder, which is mixed with water or juice and usually recommended to be consumed alongside a meal.
Inulin is a type of fibre and a prebiotic (a source of food for the “good” bacteria in the gut), explains Thornton-Wood. It is found in foods such as onion, garlic and Jerusalem artichoke but it is also available as an inulin supplement and contained in chicory supplements. Inulin has been linked with a positive impact on the gut microbiome, constipation and blood sugar regulation, she says. Inulin supplements are typically powders which are mixed with drinks.
Flaxseeds have been linked to lower cholesterol levels, says Gill. It can be bought in seed form and added to meals such as yogurts and salads. It also comes in capsule form, which is typically recommended to have with a meal.
“The ZOE Daily30+ supplement contains an assorted mix of wholefood ingredients,” such as beetroot, quinoa, red lentils, and healthy fats from walnuts and flaxseeds, says Gill. One scoop contains 5g of fibre and can be added to salads, eggs and pasta.
“It’s a versatile fibre supplement that can be added to a whole range of meals,” she says. “If you enjoy the taste and convenience, there is no reason not to include it in your diet.”
If cost is a barrier (a one-month supply costs £39), Gill recommends making your own plant-based mixes using nuts, seeds, dried fruit, dried beans, herbs and spices.
“I would avoid fibre gummies because they often contain added and unnecessary ingredients, such as sugars and preservatives,” says Gill. 
Additionally, certain prebiotics at higher doses can be problematic if you have a sensitive gut, she notes.
“Avoid the ones that are promoted for weight loss, forming a gel in the stomach,” says Thornton-Wood.
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