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Cheapest FOS on iHerb

Ranked by real cost per 100 mg of FOS — cheapest value first.

Prices updated Jul 25, 2026 · 14 products · Prices in USD

The priciest option here costs about 273.1× more per 100 mg of FOS than the best-value pick Youtheory. For the same daily dose, choosing by cost per unit instead of sticker price can meaningfully cut your yearly spend.
#ProductDoseServingsPrice (USD)Cost per 100 mg
1
Youtheory, Spore Probiotic Powder, 6 Billion CFU, 3.45 oz (97 g)
Youtheory, Spore Probiotic Powder, 6 Billion CFU, 3.45 oz (97 g)
Youtheory
1,000 mg3022.390.075View on iHerb →
2
Deva, 3-in-1 Vegan Probiotic, 5 Billion CFU, 90 Vegan Caps
Deva, 3-in-1 Vegan Probiotic, 5 Billion CFU, 90 Vegan Caps
Deva
100 mg19023.990.126View on iHerb →
3
DaVinci Laboratories, D-Mannose Complex, Powdered Drink Mix, 5.95 oz (168.57 g)
DaVinci Laboratories, D-Mannose Complex, Powdered Drink Mix, 5.95 oz (168.57 g)
DaVinci Laboratories
1,000 mg3054.220.181View on iHerb →
4
NaturesPlus, Acti-Zyme, 180 Vegan Capsules
NaturesPlus, Acti-Zyme, 180 Vegan Capsules
NaturesPlus
100 mg9042.460.472View on iHerb →
5
NaturesPlus, Acti-Zyme, Activated Digested Aid, 90 Vegan Capsules
NaturesPlus, Acti-Zyme, Activated Digested Aid, 90 Vegan Capsules
NaturesPlus
100 mg4523.760.528View on iHerb →
6
Live Conscious, Beyond Greens, Energy, Detox & Immunity Mix, Light Matcha, 4 oz (115 g)
Live Conscious, Beyond Greens, Energy, Detox & Immunity Mix, Light Matcha, 4 oz (115 g)
Live Conscious
190 mg3039.990.702View on iHerb →
7
Bluebonnet Nutrition, Pre, Pro, Post Probiotic, 30 Vegetable Capsules
Bluebonnet Nutrition, Pre, Pro, Post Probiotic, 30 Vegetable Capsules
Bluebonnet Nutrition
120 mg3030.360.843View on iHerb →
8
Cymbiotika, Probiotic, 50 Billion CFU, 90 Capsules
Cymbiotika, Probiotic, 50 Billion CFU, 90 Capsules
Cymbiotika
150 mg3088.991.98View on iHerb →
9
Swanson, Women's Daily Probiotic + Prebiotic FOS With Cranberry, 35 Billion CFU, 60 Vegan Capsules
Swanson, Women's Daily Probiotic + Prebiotic FOS With Cranberry, 35 Billion CFU, 60 Vegan Capsules
Swanson
50 mg3032.992.20View on iHerb →
10
Nordic Naturals, Nordic Flora Probiotic, Immune Health, 60 Billion CFU, 30 Capsules
Nordic Naturals, Nordic Flora Probiotic, Immune Health, 60 Billion CFU, 30 Capsules
Nordic Naturals
20 mg3042.467.08View on iHerb →
11
Nordic Naturals, Nordic Flora Probiotic, Women's Balance, 30 Capsules
Nordic Naturals, Nordic Flora Probiotic, Women's Balance, 30 Capsules
Nordic Naturals
20 mg3044.167.36View on iHerb →
12
Nordic Naturals, Nordic Flora Probiotic, Maximum Care, 90 Billion CFU, 30 Capsules
Nordic Naturals, Nordic Flora Probiotic, Maximum Care, 90 Billion CFU, 30 Capsules
Nordic Naturals
20 mg3050.968.49View on iHerb →
13
Her Own, Probiotic Gummies, Berry, 60 Gummies
Her Own, Probiotic Gummies, Berry, 60 Gummies
Her Own
5 g3018.9913.19View on iHerb →
14
Nordic Naturals, Nordic Flora Probiotic, Comfort, 15 Billion CFU, 30 Capsules
Nordic Naturals, Nordic Flora Probiotic, Comfort, 15 Billion CFU, 30 Capsules
Nordic Naturals
5 mg3030.5620.37View on iHerb →

How we rank FOS

Two supplements can list the same dose per serving yet cost very differently once you account for how many servings are in the bottle. We calculate the total nutrient in each container (dose per serving × servings per container), divide the current price by that total, and rank by the resulting cost per unit. Lower is better. Because prices are refreshed automatically, this ranking reflects today's iHerb pricing rather than a snapshot from months ago.

Cost per unit is a starting point, not the whole story — the ideal form, third-party testing, and other ingredients matter too. Always check the label and consult a healthcare professional before starting a supplement.

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Prices update automatically and may differ from iHerb at checkout. Rankings are based on cost per unit of the listed nutrient and are for informational purposes only — not medical advice. Links to iHerb are affiliate links.