Walk into any supermarket and there they are: bright, cheerful cans of prebiotic fizzy drink, sitting right next to the Fanta Lemon and promising a more microbiome-friendly way to get your fix while feeding your gut. Influencers appear to love them. Your favourite podcast is probably sponsored by them. And their pitch is rather compelling: crack open a can, consume a few grams of fibre and call it gut health.

But do these drinks actually offer a meaningful gut health benefit – or are they just sugary soft drinks with added fibre and a wellness makeover? New research has raised some questions after an analysis of 108 prebiotic sodas found that the average can contained roughly as much sugar as fibre: around 5g of each.

The research, which looked at the labels of US products, has been presented at a nutrition conference but not yet published in a peer-reviewed journal. Still, it raises a question worth asking: before you swap your usual Diet Coke for something more ‘happy-gut coded’, what does the science say?

What are prebiotic fizzy drinks?

If you're not sure what we're talking about, prebiotic fizzy drinks – such as Living Things Soda, Fibe Prebiotic Soda and XOXO Prebiotic Soda – are functional drinks designed to feed certain beneficial gut microbes.

Usually packaged in bright pink or lime green cans, these drinks offer the sweetness and fizz of a conventional soft drink alongside ingredients such as inulin, fructooligosaccharides (FOS) or galactooligosaccharides (GOS).

Unlike probiotics, they don’t supply live bacteria; instead, prebiotics provide fuel for certain bacteria already living in your gut.

Are prebiotic fizzy drinks actually good for your gut?

Current UK guidelines recommend that adults consume 30g of fibre a day, yet most of us fall well short. According to registered dietitian, gut-health researcher and author of Fibre Power, Dr Emily Leeming, 96% of Brits aren’t getting enough.

‘In that context, any additional fibre being added is generally a good thing,’ she says.

But there is a catch. ‘The amount of prebiotic fibres that these drinks contain is often not in large enough quantities for a measurable effect. The fibre added tends to be just one type of fibre too, unlike fibre-rich foods which contain a wide variety of different types of fibres for your health.’

Leeming warns that some brands use this added fibre to create ‘a kind of health halo effect for their product, when actually it's ultimately still a sweetened fizzy drink that we should consider more as something to enjoy occasionally than as a health food’.

Natasha Draycott, lead nutritionist at Rheal Superfoods, agrees that the benefit depends on the individual product – and, crucially, what it replaces in your diet.

‘Most [prebiotic drinks] contain around 5g of prebiotic fibre, which can certainly contribute to your overall intake, but they shouldn't replace fibre-rich foods,’ says Draycott.

‘Build your diet around whole foods first, then think of prebiotic drinks as an addition.’

Should you worry about the sugar and sweeteners?

The researchers found that the average prebiotic fizzy drink contained around 5g of sugar – which is way less sugar than many conventional full-sugar alternatives (a 330ml can of Coca‑Cola, for example, has around 35g of sugar).

Almost two-thirds of the prebiotic drinks analysed also contained low- or no-calorie sweeteners such as stevia. But an equal number of grams of sugar and fibre doesn’t mean one somehow cancels out the other.

‘For someone swapping a full-sugar fizzy drink for a prebiotic alternative, that’s likely to be a positive step,’ says Draycott. ‘But if you’re already drinking water or unsweetened sparkling water, I wouldn’t recommend adding a prebiotic drink purely for gut health.’

Who should avoid prebiotic fizzy drinks?

Some people may find that increasing fibre in their diet comes with some uncomfortable side effects – including bloating, wind or discomfort.

People with IBS may be particularly sensitive to fibres such as inulin, says Dr Leeming, although that doesn’t mean everyone with IBS needs to avoid these drinks.

‘Some fibres used in prebiotic drinks, such as inulin and chicory-root fibre, are high-FODMAP ingredients, so they can trigger symptoms in some people with IBS,’ explains Draycott. ‘It’s also worth remembering that the carbonation itself can cause bloating.’

If you know you’re sensitive to added fibre, Draycott recommends starting with a small serving and increasing it gradually.

The bottom line

Yes, popular prebiotic fizzy drinks can contribute to your overall daily fibre intake and may be a useful lower-sugar swap for a regular can of fizzy lemonade. But whole foods remain the gold standard.

‘If you're wanting to look after your gut health, focus on whole foods first,’ says Dr Leeming. ‘Think onions, asparagus, garlic, leeks, and beans – they are all great sources of different prebiotic fibres.’