The short answer: prebiotic fiber water is still water with a few grams of prebiotic fiber dissolved in it. Your body can't digest that fiber, so it travels on to your gut, where it becomes food for the helpful bacteria that live there. You get a drink that hydrates like water and tops up a nutrient most of us don't get enough of.
What is prebiotic fiber water?
It's what it sounds like: water, plus prebiotic fiber, usually with a light fruit flavour. It isn't a soda, a juice or a shake. A good one is low in calories, has little or no sugar, and drinks like lightly flavoured water rather than a supplement.
Good Inside is Egypt's first prebiotic fiber water. Every 500 ml bottle is still (not fizzy) and has 5 g of prebiotic fiber, zero sugar and just 7 calories. The full breakdown is on our nutrition facts page.
What does "prebiotic" actually mean?
Your gut is home to trillions of bacteria, and many of them work in your favour. A prebiotic is food for those helpful microbes. The international expert panel that defines the term (ISAPP) describes a prebiotic as something your gut microbes selectively use, and that benefits your health as a result. Put simply: you can't digest it, your good bacteria can, and you're better off for it.
Most prebiotics are types of fiber, but not every fiber is a prebiotic. And prebiotics are not the same thing as probiotics, which are live bacteria. If those two words blur together, read our guide to prebiotic vs probiotic.
What's the fiber in it? Meet resistant dextrin
The fiber in Good Inside is called resistant dextrin. It's made from starch, and the name tells you what it does: it resists digestion. Instead of being broken down into sugar in your small intestine, most of it carries on to your large intestine, where your gut bacteria slowly ferment it.
Three things make it a good fit for a drink:
- It dissolves completely. No grit, no gel, no thick texture. The water still looks and drinks like water.
- It has almost no taste, so the natural fruit flavours do the talking.
- It ferments slowly. Fast-fermenting fibers are the ones most likely to leave you gassy. In clinical studies, resistant dextrin has been well tolerated at daily amounts several times higher than the 5 g in one bottle.
It also counts as real dietary fiber. The US Food and Drug Administration reviewed the evidence and allows resistant dextrin to be declared as dietary fiber on nutrition labels.
How is it different from soda, fiber powders and plain water?
| Drink | What it is | Good to know |
|---|---|---|
| Plain water | Hydration, nothing else | Still the foundation of your day. No fiber. |
| Prebiotic fiber water | Still water with prebiotic fiber dissolved in it | Drinks like water. Good Inside has 5 g of fiber, zero sugar, 7 calories and no caffeine. |
| Prebiotic soda | A fizzy soft drink with added fiber | Fiber, sugar and sweeteners vary a lot from brand to brand, so check the label. |
| Fiber powders and husks, such as psyllium | Fiber you stir into water yourself | Psyllium soaks up water and forms a gel, so it needs plenty of liquid. Not everyone enjoys the texture. |
What can prebiotic fiber water do for you?
- It feeds your good gut bacteria. The fiber in each bottle helps nourish beneficial gut bacteria and supports everyday digestive comfort.
- It helps close your fiber gap. The World Health Organization recommends at least 25 g of fiber a day for adults, and research suggests most people worldwide eat less than 20 g. One bottle gives you 5 g, around 20% of that daily target. Our guide to how much fiber you need a day shows what the rest can look like.
- It helps you feel fuller. Prebiotic fiber helps you feel fuller for longer, which makes mindful eating a little easier.
- It's kinder to your blood sugar than a sugary drink. There's no sugar in the bottle, and resistant dextrin isn't digested like sugar. It supports a more gradual blood glucose response, especially when you drink it with a meal.
- It makes water more interesting. If flavour is what gets you to drink more through the day, that counts too.
One honest note: a fiber drink is a top-up, not a free pass. The WHO's advice is about fiber that comes naturally in vegetables, fruit, pulses and whole grains, and those foods bring vitamins and minerals no drink can. Think of a bottle as an easy 5 g on top of a decent plate, and enjoy it as part of a healthy diet.
Will it make me bloated?
Any fiber can cause some gas if you go from very little to a lot overnight. That's why the usual advice is to increase fiber gradually and drink plenty of fluids.
Good Inside is formulated specifically to reduce that risk. Resistant dextrin is one of the most well-tolerated prebiotic fibers, especially compared with fibers that ferment more aggressively. If you're new to fiber, start with one bottle a day and let your digestive system settle in.
When and how should you drink it?
Whenever you like. Many people keep a bottle at their desk, have one after a workout, or drink it with a meal, which is also when the fiber's gentle effect on blood sugar helps most. It's still and caffeine-free, so it works at any time of day.
- How much: many adults comfortably drink one to two bottles a day. Children under 13 should stick to one.
- How to serve: cold. It tastes best straight from the fridge.
- How to store: in the fridge if you can. Otherwise keep it below 25°C, somewhere dark and out of the sun.
Who is it for?
- You know you don't eat enough vegetables, fruit and pulses on most days.
- You're cutting back on sugary soft drinks and juices but still want some flavour.
- You've tried fiber powders and couldn't stick with them.
- You want one small daily habit that looks after your gut.
Check with your doctor first if you have a digestive condition, take regular medication, or are pregnant and have specific concerns. Fiber supplements can change how some medicines and blood sugar behave.
Quick questions
Is prebiotic fiber water the same as a probiotic drink?
No. Probiotic drinks contain live bacteria. Prebiotic fiber water contains no bacteria at all. It feeds the good bacteria you already have.
Does it contain sugar or caffeine?
Good Inside has 0 g of sugar and no caffeine. The light sweetness comes from sucralose, a zero-calorie sweetener, which is how a whole bottle stays at 7 calories. The full ingredients list is in our FAQ.
Can I drink it every day?
Yes. Good Inside is designed for daily drinking. The fiber dose is moderate and gentle, and suitable for long-term use as part of a balanced diet.
Sources
- International Scientific Association for Probiotics and Prebiotics (ISAPP): the consensus definition of a prebiotic
- World Health Organization: updated guidelines on carbohydrates, including fiber (2023)
- The Lancet: fiber intake and health, a review commissioned by the WHO (2019)
- US Food and Drug Administration: questions and answers on dietary fiber
- Frontiers in Nutrition: randomized controlled trial of resistant dextrin in healthy adults (2026)
- Mayo Clinic: fiber supplements, safe to take every day?
- Cleveland Clinic: psyllium husk, what it is and how it works
This article is for general information and isn't medical advice. If you have a health condition or take medication, talk to your doctor before changing your diet.
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