Do Kids Need Different Probiotics to Adults?

What Parents Should Know About Children's Gut Health

It's around this time of year that the chance of a child taking antibiotics increases and with that some the question about probiotics. Whether it's for an ear infection or a cough that wouldn't shift, antibiotics can sometimes be necessary so I'm not here to dismiss their use entirely.

But what I do want to cover is whether the probiotic in your cupboard does the same job for your child as they would for you. The honest answer is that a child's gut is evolving at pace and is at a different stage of life to yours, therefore, the research behind one product doesn't automatically carry over to another.

A Child's Gut Is Not Just a Smaller Adult Gut

The gut microbiome develops in stages rather than arriving fully formed. The large TEDDY study, which followed children from three months to almost four years, identified three distinct phases, developmental, transitional and stable. Even then, the work isn't finished. So much research is ongoing and takes a long time to evolve with confirmed findings.

A Swedish study of 471 children found the gut microbiota was still maturing at five years old, with only a small minority of five-year-olds showing an adult-like profile. A review of the first decade of life describes childhood as a period in which diet, infections, medicines and environment continue to shape which bacteria settle in.

Why does this matter? Well, for a few practical reasons.

• A developing microbiome may respond differently to the same probiotic than an established adult one.
• Most adult probiotics have been tested in adults, at adult doses, so those results can't simply be scaled down (where vitamins and minerals can be).
• The best-researched product is no use if a child won't take it, so format matters more than we tend to admit.

Why Strain Specificity Matters More Than CFU Count

Probiotic labels often compete on numbers, with more strains and bigger CFU (Colony Forming Unit. Just think of it as the number of live bacteria per dose.) counts presented as better. The research tells a different story.

A systematic review of 228 trials found that probiotic effects are both strain-specific and condition-specific, so the results for one strain can't be assumed for another, even within the same species. A follow-up review comparing single strains with multi-strain mixtures found that, in most cases, mixtures were not significantly more effective; the authors concluded that choice should be guided by trial evidence rather than the number of strains on the pack.

When I look at a children's probiotic, I ask three questions.

• Is each strain named in full?
• Has that exact strain been studied?
• Is the amount broadly in line with what was used in the research?

Why We Chose Bacillus Subtilis DE111 and Bacillus Coagulans SNZ 1969

When Tonic reformulated Kids Pre + Probio, the aim was to combine two strains that each bring their own body of research.

Bacillus subtilis DE111 has been studied in young children specifically. In a randomised, placebo-controlled trial of 91 healthy children aged two to six attending daycare, eight weeks of DE111 didn't disrupt the overall balance of the microbiome but was linked to greater bacterial diversity, changes described as subtle but positive. A follow-up trial in the same age group reported it was well tolerated.

Bacillus coagulans SNZ 1969 has a long history of use, with randomised trials in adults looking at bowel habits and immune markers. Researchers have been keen to explore its benefits in children too, with a trial in school-aged children now ongoing.

Both are spore-forming strains. Spores have a protective outer coat that helps them tolerate stomach acid and stay stable at room temperature, which matters in a gummy that lives in a kitchen cupboard rather than a fridge.

Antibiotics and Probiotics: Is There a Benefit?

Antibiotics are sometimes essential, but they can also disrupt gut bacteria along the way. A 2019 Cochrane review of 33 trials in children found that probiotics taken alongside antibiotics reduced the risk of antibiotic-associated diarrhoea from around 19% to 8%. Roughly one case was prevented for every nine children treated, and the effect was strongest at higher doses.

The review included Bacillus species among the probiotics studied, and the benefit was clearest at higher doses of 5 billion CFU a day or more. The strains reviewed in this study aren't the strains in Kids Pre + Probio – we didn't want to develop a product that was only for antibiotic-associated diarrhoea. Tonic designed the Pre + Probio Gummie for a place in the everyday routine for healthy tums all year round.

That said, the positive news is DE111 has been studied in two- to six-year-olds, and a follow-up trial in daycare children reported fewer days of tummy discomfort compared with placebo. Pair that with prebiotic fibre to feed the bacteria already there, and it's a simple way to support their gut as they get back to normal.

Where Prebiotics Fit In

If probiotics are the bacteria, prebiotics are what feeds them. The current scientific consensus describes a prebiotic as a substance selectively used by the body's own microbes in a way that benefits health. Certain fibres, such as fructo-oligosaccharides (FOS), fit this description and is included in Tonic's Pre + Probio Gummie for this reason.

Fibre is an area where many children fall short. UK guidance recommends around 15g a day for 2–5 year olds, 20g for 5–11 year olds and 25g for 11–16 year olds, and most children don't reach these amounts (sadly another recommendation we're not hitting in the UK). Oats, beans, lentils, wholegrain bread, bananas, onions and leeks are all useful everyday sources, and my Five Sneaky Ways to Add More Fibre to Your Kids' Diet blog has plenty more ideas. A supplement can top up, but it can't replace a varied plate.

When Gut Support Is Particularly Relevant

In my experience, parents tend to think about gut health at a few predictable points.

• After a course of antibiotics, once your GP or pharmacist is happy
• Through autumn and winter, when new terms and shared classrooms bring a run of bugs (my winter immunity blog covers the wider picture)
• During fussy-eating phases, when fruit, vegetables and wholegrains are the first things to go
• Around changes in routine, such as travel or starting school

What to Look For in a Children's Probiotic

• Named strains with full strain codes (e.g. Bacillus Subtilis DE111), not just a species (e.g. Bacillus).
• Research in children, or at least in humans, for the specific strains used.
• A clear age range and dose, designed for children rather than adapted from an adult product.
• Prebiotic fibre to feed the bacteria already there.
• Stability, either shelf-stable strains or clear storage instructions.
• A format they'll take, ideally without added sugar.
• Transparency from a brand willing to explain its ingredients.

For babies and children under three, speak to your GP or health visitor before giving any supplement.

How Kids Pre + Probio Is Different

Tonic Kids Pre + Probio was built around the criteria above. Each serving of two blackcurrant gummies combines two named, spore-forming strains, Bacillus subtilis DE111 and Bacillus coagulans SNZ 1969, with prebiotic fibre from beetroot (FOS). It's designed for children aged 3–12, needs no fridge, and contains no added sugar or artificial sweeteners.

As ever, food comes first. Supplements are there to fill genuine gaps, not to replace a plate with a decent variety of fruit, vegetables, protein and fibre-rich carbohydrates – which the microbiome needs just as much!

This article is for informational purposes only and does not constitute medical advice.

About the Author

Natalie Louise Burrows is a registered nutritional therapist (BANT, CNHC) and clinic director at Integral Wellness.