DOSERANKEVIDENCE-BASED SUPPLEMENTS© 2026 DoseRank · Evidence-based supplements
Methodology·Outcomes·Categories·Blog
Support·Feedback
DOSERANKEVIDENCE-BASED SUPPLEMENTSFull analysis

The short answer · Gut microbiome composition

Take fructooligosaccharides (fos) for gut microbiome composition. This is the one to buy.

NOW Foods, Certified Organic Inulin, Prebiotic Pure Powder, 8 oz (227 g)
1

NOW Foods, Certified Organic Inulin, Prebiotic Pure Powder, 8 oz (227 g)

4.7· 23,425 ratings· $0.17/serving

DoseRank score85

Fructooligosaccharides (FOS) 3.3 g — inside the studied 2.5-10 g window

Of 1,088 products scored for Gut microbiome composition, NOW Foods, Certified Organic Inulin, Prebiotic Pure Powder, 8 oz (227 g) ranks #1 with a DoseRank score of 85. Fructooligosaccharides (FOS) is the strongest evidence signal for this outcome.

View on iHerb
The form“Why Fructooligosaccharides (FOS) — not Galactooligosaccharides (GOS) or Inulin?”Evidence Strong evidence

Fructooligosaccharides (FOS) is the strongest evidence signal for this outcome.

  • Fructooligosaccharides (FOS)The pick

    Strong evidence · 3.3 g

    Short-chain fructose polymers that selectively feed beneficial gut bacteria; function as a prebiotic fiber and may improve stool consistency at doses of 2.5-10 g daily.

  • Galactooligosaccharides (GOS)

    Strong evidence · 7.9 g

    Prebiotic oligosaccharides derived from lactose; selectively stimulate bifidobacteria, support infant gut development, and are naturally found in human breast milk.

  • Inulin

    Strong evidence · 8100 mg

    Soluble prebiotic fiber from chicory root; selectively feeds Bifidobacterium and Lactobacillus in the colon, though it can cause gas at higher doses.

Buy the #1 pick

Questions

Frequently asked

NOW Foods, Certified Organic Inulin, Prebiotic Pure Powder, 8 oz (227 g) ranks #1 for Gut microbiome composition with a DoseRank score of 85. The score blends clinical strength, evidence, dose fit, trust signals and value across 1,088 products scored for this outcome.

Fructooligosaccharides (FOS) is the strongest evidence signal for this outcome.

Fructooligosaccharides (FOS) at 3.3 g lands inside the studied 2.5-10 g window. DoseRank scores this product's dose fit at 69 out of 100.

NOW Foods, Certified Organic Inulin, Prebiotic Pure Powder, 8 oz (227 g) works out at $0.17 per serving. $0.17 per serving — mid price tier for this outcome. Nothing else in this ranking costs less per serving.

No. Retailer links may be affiliate links, but rankings and placement are never paid. Every product is scored by the same public model, and the ranking is recomputed from the underlying product data rather than edited by hand.

Keep exploring

Other outcomes

  • Microbiome diversityEcologic diversity of gut microbial communities.

Use rankings as research support

DoseRank rankings are informational and not medical advice. If you are pregnant, breastfeeding, using medications, or managing a health condition, ask a qualified clinician whether a supplement fits your situation. Stop use and report concerning adverse events to a clinician, the product maker, or the retailer.

Disclosure

Retailer links may be affiliate links. Rankings and placement are not paid placement.

NOW Foods, Certified Organic Inulin, Prebiotic Pure Powder, 8 oz (227 g)

$0.17/serving · ★ 4.7 · In stock

60-sec quizView on iHerb
— $0.17/sv
60-sec quiz instead
Cheaper alternative$0.07 per servingMicro Ingredients, Organic Inulin Powder, Unflavored, 2.2 lb (998 g)

Retailer links may be affiliate links. Rankings and placement are never paid.

The dose“Is the dose actually effective?”Dose fit 69

Fructooligosaccharides (FOS) at 3.3 g lands inside the studied 2.5-10 g window.

Fructooligosaccharides (FOS)

Studied window 2.5-10 g · this pick 3.3 g

The ranking“Why should I trust this pick?”Trust 93

Strong trust signals — consistently high marks from verified buyer ratings. Each product gets a DoseRank score blending clinical strength, evidence, dose fit, trust and value. Retailer links may be affiliate links — the scoring model decides placement, never payment from a brand.

  • 1,088 products scored
  • Never paid placement
  • Evidence level: Strong · 92
  • 220 brands
  • 16 ingredients
See the full analysis — every score, every productHow the ranking works
The price“Can I do better than $0.17 a serving?”Value 78

$0.17 per serving — mid price tier for this outcome. Nothing else in this ranking costs less per serving.

Ready?

The #1 pick is $0.17 a serving.

NOW Foods, Certified Organic Inulin, Prebiotic Pure Powder, 8 oz (227 g) — in stock at a tracked retailer.

View on iHerb
Want it personal instead?

A saved, shareable breakdown: your matched products, dose math, and interaction flags to discuss with a clinician.

Or take the 60-sec quiz →