Product fact sheet
NOW NutraFlora FOS Powder: 5 g scFOS Evidence, Dose & Tolerability
NOW NutraFlora FOS provides 5 g short-chain FOS per serving, a dose studied for bifidogenic effects; fermentation-related gas and bloating can limit tolerance.
A straightforward 5 g short-chain FOS powder with no other ingredients. The serving exactly matches one dose in human scFOS dose-response work that increased fecal bifidobacteria, although the largest bifidogenic response in that trial occurred at 10 g/day. FOS remains highly fermentable and can aggravate bloating in sensitive users.
Adults specifically comparing short-chain FOS at a human-studied gram dose, Shoppers who prefer a single-ingredient prebiotic powder
People who know fructans worsen their IBS or low-FODMAP symptoms, Anyone expecting evidence that 5 g FOS treats stress, inflammation or mental-health symptoms
Key tradeoff: The 5 g serving matches a dose used in human scFOS research, but FOS is highly fermentable and the clearest evidence concerns microbiota changes rather than disease outcomes.
This is a factual fit-and-tradeoff summary, not a product recommendation. Formula, device and brand claims remain manufacturer claims unless the cited source is explicitly regulatory or independent testing.
NOW NutraFlora FOS is unusually simple: 5 g of short-chain fructooligosaccharides (scFOS) per two-teaspoon serving and no other ingredients. That quantity can be matched directly to human dose-response research.
How well does 5 g match human evidence?
A randomized dose-response study in healthy adults tested 2.5, 5, 7.5 and 10 g/day scFOS. Bifidobacteria increased across the tested scFOS doses, with the largest response at 10 g/day. The current NOW serving therefore sits inside a genuinely studied range rather than borrowing evidence from a very different dose.
That is useful evidence for a bifidogenic effect. It is not proof that five grams will relieve abdominal pain, normalize every bowel symptom or improve systemic health.
A newer controlled crossover study using 5 g FOS plus 5 g GOS daily altered aspects of the microbiota but did not establish improvements in biological stress/inflammation markers or mental-health symptoms. Microbiota change and clinical benefit therefore need to remain separate endpoints.
Current label snapshot
| Feature | Specification |
|---|---|
| Main substrate | NutraFlora short-chain FOS |
| Amount | 5 g per 2 teaspoons |
| Other ingredients | None |
| Suggested use | Begin lower and gradually increase up to 2 teaspoons daily |
| Storage | Cool, dry place |
The main tradeoff: fermentation
FOS is efficiently fermented. That is part of why it can change bacterial populations, but it is also why it may increase gas, bloating and distension. People who already know that fructans worsen their IBS symptoms may find a slower-fermenting substrate such as resistant maltodextrin, PHGG or resistant starch easier to test.
Compare dose + endpoint + tolerance rather than treating FOS as uniformly helpful or unhelpful.
Who is it most useful for?
This is a rational product to compare when the goal is specifically a single-ingredient scFOS trial and the user wants a gram dose that can be tied to human studies.
It is a weaker choice when the goal is a defined medical condition and another fiber has stronger symptom-level evidence. For example, psyllium has professional-guideline support for global IBS symptoms, while acacia now has randomized stool-frequency data in IBS-C.
See the prebiotic substrate guide for side-by-side comparisons of FOS, XOS, PHGG, GOS, resistant maltodextrin, acacia, HMOs and resistant starch.
Formula facts
Ingredients, actives and label details
- Prebiotic substrate
- NutraFlora short-chain fructooligosaccharides (scFOS) Basis: Manufacturer Source: NOW NutraFlora FOS Powder — official product information
- FOS per serving
- 5 g per 2 teaspoons Basis: Manufacturer Source: NOW NutraFlora FOS Powder — official product information
- Other ingredients
- None Basis: Manufacturer Source: NOW NutraFlora FOS Powder — official product information
- Dose-to-trial fit
- Human scFOS dose-response research tested 2.5, 5, 7.5 and 10 g/day; 5 g/day increased bifidobacteria versus baseline and 10 g/day produced the largest response Basis: Randomized trial Source: The capacity of short-chain fructo-oligosaccharides to stimulate faecal bifidobacteria: a dose-response relationship study in healthy humans
- Tolerability signal
- FOS is rapidly fermentable; bloating and gas can occur, particularly in fructan-sensitive people Basis: Randomized trial Source: The capacity of short-chain fructo-oligosaccharides to stimulate faecal bifidobacteria: a dose-response relationship study in healthy humans
Source labels preserve provenance. Manufacturer specifications, ingredient lists and performance claims are not treated as independent clinical evidence; regulatory records and independent measurements are identified separately when available.
Safety first
What should make you slow down?
Use the product as directed, avoid treating concentrated wellness products as automatically harmless, and ask a qualified clinician when your situation or medication use makes the decision less routine.
Where to buy
Current tracked merchants
Commerce note: merchant economics never enter our editorial score. Affiliate links are identified as (paid link) and use sponsored-link markup.
No merchant destination is currently tracked for this product.
Source trail
Primary documents and supporting evidence
- NOW NutraFlora FOS Powder — official product informationNOW Foods · Manufacturer · retrieved 2026-08-12
- The capacity of short-chain fructo-oligosaccharides to stimulate faecal bifidobacteria: a dose-response relationship study in healthy humansNutrition Journal · Professional health · retrieved 2026-08-12
- Prebiotic Consumption Alters Microbiota but Not Biological Markers of Stress and Inflammation or Mental Health Symptoms in Healthy AdultsThe Journal of Nutrition · Professional health · retrieved 2026-08-12