Prebiotics
Prebiotics are non-digestible fibres that selectively feed beneficial gut bacteria. They are distinct from probiotics (live bacteria) and are increasingly combined with probiotics in synbiotic formulations.
Definition
Prebiotics are non-digestible food components — primarily dietary fibres and some polyphenols — that selectively stimulate the growth or activity of beneficial gut bacteria. Unlike probiotics (live bacteria you consume), prebiotics feed the bacteria already living in your gut.
The Most Studied Prebiotics
- Inulin and FOS (fructooligosaccharides): Found naturally in chicory root, onions, garlic, and Jerusalem artichoke. Selectively feeds Bifidobacterium and Lactobacillus species. Backed by robust RCT evidence (Gibson et al, Gut 2004, PMID 15123786).
- GOS (galactooligosaccharides): Found in breast milk; associated with infant gut microbiome development. Backed by evidence in infant and adult populations.
- Resistant starch: Potato starch, green banana starch — feeds butyrate-producing bacteria like Faecalibacterium prausnitzii.
- Lactulose: A synthetic prebiotic used clinically for hepatic encephalopathy. Strongest evidence base of any prebiotic for a clinical indication.
- Punicalagin (Indian pomegranate): Used by Seed DS-01 as its prebiotic component. Antioxidant polyphenol; some evidence suggests it may act as a selective substrate for gut bacteria, but the evidence base is thinner than inulin/FOS.
Prebiotics vs Probiotics vs Synbiotics
| Term | Definition |
|---|---|
| Probiotic | Live microorganisms that, when consumed in adequate amounts, confer a health benefit |
| Prebiotic | Selectively fermented ingredient that feeds beneficial gut bacteria |
| Synbiotic | A product combining both probiotic and prebiotic components |
Do Prebiotics Cause Bloating?
Some people experience increased bloating, gas, and discomfort when starting a prebiotic — particularly with inulin and FOS. This is because gut bacteria ferment the prebiotic and produce gas as a byproduct. This typically resolves within 2-3 weeks as the microbiome adapts. Start with a low dose if you are bloat-sensitive.
Bottom Line
Prebiotics are a legitimate and evidence-backed component of gut health support. They are particularly valuable when combined with probiotics (synbiotic formulation) for post-antibiotic recovery, where feeding the recovering microbiome may accelerate diversity restoration.