What is the difference between probiotics and prebiotics?

The two terms are often used interchangeably, but they refer to different things and both have settled scientific definitions.

What is a probiotic?

The international consensus definition is live microorganisms that, when given in adequate amounts, confer a health benefit on the host. The same group additionally recommends that the strain be identified and the count stated.

The operative word is live. Microorganisms that have been heat-treated until they are no longer viable fall outside the term, which is why storage matters for this category of product.

What is a prebiotic?

A prebiotic is a substrate selectively used by microorganisms in the gut. Most are particular fibres, such as inulin and fructo-oligosaccharide.

Not all fibre is prebiotic. The definition is narrower than "fibre" in general.

What is a synbiotic?

A product containing both in one formulation. That is a matter of composition, not a grade of quality.

What can be said in Thailand?

For prebiotics, the Food Division issued an addendum on 31 October 2025 setting out wording for chicory inulin and fructo-oligosaccharide, with amount conditions — inulin, for instance, must be present at a minimum of 4 g per serving, and the label must state that at least 12 g a day should be consumed.

Those conditions sit above what most products contain, so having the ingredient in a formulation does not automatically meet them.

Where do they occur in food?

Live microorganisms occur in some fermented foods, such as cultured milk drinks and yoghurts labelled as containing live cultures.

Inulin and fructo-oligosaccharide occur in onion, garlic, spring onion, asparagus and banana.

Dietary supplements are not intended to prevent, treat or cure any disease.