Solnul® - Clinical Research Data Summary

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Solnul® Resistant Potato Starch (RS2) Prebiotic Fiber

Solnul® is a clinically studied ingredient used in the following Silver Fern™ Brand products:

Introduction

Solnul® is a clinically studied, low-dose prebiotic resistant potato starch (RS2) designed to support gut health by selectively feeding beneficial microbes — including Bifidobacterium and Akkermansia. Unlike many fibers, Solnul® has been studied at doses as low as 3.5 grams per day and is generally well tolerated. It is low-FODMAP and ferments slowly in the gut, helping support digestive comfort and regularity.*

Backed by human clinical and metabolomic research, Solnul® has been shown to support a healthy gut microbiome and may influence microbial metabolites associated with digestive and metabolic physiology. Its neutral taste and whole-food, upcycled sourcing make it easy to incorporate into daily nutrition.*

These are the studies for Solnul®. Below, we provided a summary of each key data for each study, along with a link to the complete clinical research.

  1. Summary of Study 1 – Full Study: https://www.mdpi.com/2072-6643/15/7/1582
  2. Summary of Study 2 – Full Study: https://www.sciencedirect.com/science/article/pii/S1756464623003407
  3. Summary of Study 3 – Full Study: https://www.mdpi.com/2218-1989/14/10/536
  4. Summary of Study 4 – Full Study: https://pubmed.ncbi.nlm.nih.gov/39605008/

Ingredient Manufacturer Link: https://solnul.com/



Study 1 Summary

Complete Study Information: https://www.mdpi.com/2072-6643/15/7/1582

Consumption of Solnul™ Resistant Potato Starch Produces Prebiotic Effects in a Randomized, Placebo-Controlled Clinical Trial
Nutrients. 2023.

This randomized, double-blind, placebo-controlled human clinical trial evaluated whether low doses of Solnul® resistant potato starch (RS2) could support beneficial changes in the gut microbiome consistent with prebiotic activity in 75 healthy adults (ages 18–69) over 4 weeks.

Study Design Highlights

  • Study design: Randomized, double-blind, placebo-controlled
  • Participants: 75 healthy adults (ages 18–69)
  • Groups: 3.5 g/day Solnul®, 7 g/day Solnul®, and digestible corn starch placebo
  • Duration: 4 weeks
  • Outcomes: Gut microbiome composition (16S rRNA sequencing), stool form and bowel movement patterns (Bristol Stool Chart)

Key Findings (What the Study Showed)

1. Prebiotic-Associated Microbiome Changes at Low Dose

Participants consuming 3.5 g/day Solnul® experienced statistically significant increases in beneficial gut bacteria vs. placebo, including Bifidobacterium and Akkermansia.

2. Improvements in Stool Consistency

Participants consuming Solnul® experienced improvements in stool consistency across the Bristol Stool Scale, including reductions in both hard stool types (Types 1–2) and loose stool types (Types 6–7).

3. Favorable Tolerability

Adverse events were mild and infrequent; no serious adverse events were reported; tolerability was comparable to placebo.

Benefits of Solnul® Demonstrated by This Study

Based directly on the clinical outcomes, Solnul® was shown to:
✓ Support increases in Bifidobacterium and Akkermansia at just 3.5 g/day
✓ Support improvements in stool consistency (fewer hard and loose stool types)
✓ Demonstrate prebiotic-associated microbiome changes at a low daily intake
✓ Be generally well tolerated in healthy adults with tolerability comparable to placebo

Why This Study Matters

Historically, resistant starch has often been studied at relatively high intake levels. This study demonstrates that as little as 3.5 g/day of resistant potato starch may support beneficial microbiome changes, making it practical to incorporate into everyday dietary routines and supplement formulations.*

Reference Link: https://www.mdpi.com/2072-6643/15/7/1582



Study 2 Summary

Complete Study Information: https://www.sciencedirect.com/science/article/pii/S1756464623003407

Resistant Potato Starch Supplementation Influences Serum Fatty Acid and Bile Acid Profiles in Healthy Adults
Journal of Functional Foods. 2023.

This randomized, double-blind, placebo-controlled post-hoc metabolomic analysis evaluated whether 3.5 g/day Solnul® (≈2.1 g RS2) could influence circulating fatty acid and bile acid profiles vs. digestible corn starch placebo in healthy adults (ages 18–69) over 4 weeks using targeted LC-MS metabolomics.

Study Design Highlights

  • Study type: Randomized, double-blind, placebo-controlled (post-hoc metabolomic analysis)
  • Dose evaluated: 3.5 g/day Solnul® (≈2.1 g RS2)
  • Duration: 4 weeks
  • Analysis: Targeted LC-MS metabolomics measuring serum free fatty acids, conjugated bile acids, and ketone bodies

Key Findings (What the Study Showed)

1. Changes in Circulating Free Fatty Acids

Statistically significant changes in circulating free fatty acid profiles vs. placebo by week 4, with reductions most notable among certain unsaturated fatty acids, suggesting resistant potato starch intake may influence circulating lipid metabolites.

2. Modulation of Bile Acid Profiles

Solnul® was associated with changes in specific conjugated secondary bile acids including taurodeoxycholic acid, taurolithocholic acid, glycolithocholic acid, and glycoallocholic acid. Total bile acid levels were not suppressed — indicating influence on bile acid pool composition rather than overall production.

3. Microbiome-Associated Metabolic Effects

Observed changes in fatty acid and bile acid metabolites were not explained by dietary changes, were not observed in the placebo group, and were associated with microbiome-derived bile acid metabolites — suggesting resistant potato starch influences circulating metabolites through gut microbiome interactions.

4. No Changes in Ketone Bodies

Ketone bodies (β-hydroxybutyrate, acetate, acetoacetate) did not significantly change, indicating that metabolic effects occurred independently of fasting-related pathways.

Benefits of Solnul® Demonstrated by This Study

Based directly on the metabolomic findings, Solnul® at 3.5 g/day was shown to:
✓ Influence circulating free fatty acid profiles vs. placebo
✓ Modulate specific secondary bile acid metabolites without suppressing total bile acids
✓ Support microbiome-associated metabolic activity detectable in circulating metabolites
✓ Produce measurable metabolic changes at a low daily intake

Why This Study Matters

This metabolomic analysis demonstrates that low-dose resistant potato starch may influence circulating metabolites associated with gut microbial activity and lipid metabolism — extending Solnul®'s evidence base beyond microbiome composition changes to measurable host metabolic outcomes.*

Reference Link: https://www.sciencedirect.com/science/article/pii/S1756464623003407



Study 3 Summary

Complete Study Information: https://www.mdpi.com/2218-1989/14/10/536

Resistant Potato Starch Supplementation Influences Circulating Histamine and Microbiome-Associated Metabolites in Healthy Adults
Metabolites. 2024.

This randomized, double-blind, placebo-controlled post-hoc metabolomic analysis evaluated whether 3.5 g/day Solnul® (≈2.1 g RS2) could influence circulating histamine levels and metabolites associated with gut microbial activity and intestinal barrier metabolism in 48 healthy adults over 4 weeks, using targeted metabolomics and 16S sequencing.

Study Design Highlights

  • Study type: Randomized, double-blind, placebo-controlled (post-hoc metabolomic analysis)
  • Participants: 48 healthy adults
  • Dose: 3.5 g/day Solnul® (≈2.1 g RS2) vs. digestible corn starch placebo
  • Duration: 4 weeks
  • Measurements: Serum histamine and metabolites, gut microbiome composition (16S), amino acids linked to intestinal barrier metabolism, polyamines, carnitine metabolites

Key Findings (What the Study Showed)

1. Changes in Circulating Histamine Levels

  • Statistically significant reductions in circulating histamine vs. placebo: ~18% reduction at week 1 and ~13% reduction at week 4
  • Changes were not associated with enzymatic histamine breakdown (no meaningful changes in DAO activity, histamine methylation products, or histidine availability)
  • Suggests reductions may relate to broader microbiome-associated metabolic changes

2. Changes in Metabolites Associated with Intestinal Barrier Metabolism

Reductions in several circulating metabolites commonly linked to intestinal barrier metabolism including hydroxylysine, asparagine, ornithine, serine, tyrosine, and acetylspermidine.

3. Changes in Carnitine Metabolites and Microbiome

Shifts in short- and medium-chain carnitine metabolites associated with fatty acid metabolism were correlated with increases in Akkermansia, suggesting interactions between microbiome composition and host metabolic pathways. Modest reductions in certain histamine-producing bacteria (Haemophilus, specific Lactobacillus strains) were also observed.

Benefits of Solnul® Demonstrated by This Study

Based directly on the metabolomic findings, Solnul® at 3.5 g/day was shown to:
✓ Support ~18% reduction in circulating histamine at week 1 vs. placebo
✓ Support ~13% reduction in circulating histamine at week 4 vs. placebo
✓ Influence metabolites associated with intestinal barrier metabolism
✓ Show carnitine metabolite changes correlated with Akkermansia increases
✓ Modestly reduce histamine-producing bacteria

Why This Study Matters

This study demonstrates that low-dose resistant potato starch may influence circulating histamine levels and metabolites related to intestinal metabolism — extending Solnul®'s evidence beyond microbiome composition to metabolites commonly studied in the context of gut physiology and barrier function.*

Reference Link: https://www.mdpi.com/2218-1989/14/10/536



Study 4 Summary

Complete Study Information: https://pubmed.ncbi.nlm.nih.gov/39605008/

Consumption of Resistant Potato Starch Influences Gut Microbiota and Self-Reported Bowel Patterns: Secondary Analysis of a Clinical Trial
BMC Nutrition. 2024.

This secondary analysis of a randomized, double-blind, placebo-controlled clinical trial evaluated relationships between gut microbiota changes and self-reported bowel patterns in 70 healthy adults (ages 18–69) consuming low-dose Solnul® (3.5 g/day or 7 g/day) vs. digestible corn starch placebo over 4 weeks.

Study Design Highlights

  • Study design: Secondary analysis of randomized, double-blind, placebo-controlled trial
  • Participants: 70 healthy adults (ages 18–69)
  • Groups: 3.5 g/day Solnul®, 7 g/day Solnul®, and placebo
  • Duration: 4 weeks
  • Measurements: Daily self-reported bowel experiences (abdominal discomfort, bloating, gas, constipation, diarrhea), Bristol Stool Chart, 16S rRNA stool microbiome sequencing, dietary intake

Key Findings (What the Study Showed)

  • Multiple statistically significant correlations identified between changes in specific bacterial taxa and changes in participant-reported bowel patterns — many occurring in participants consuming Solnul®
  • Microbiome changes and their associations with bowel patterns varied across individuals, suggesting responses to prebiotic fibers may depend in part on existing gut microbiome composition
  • Observed microbiome relationships were independent of dietary intake changes (macronutrients and fiber did not significantly change during the study)
  • Solnul® supplementation was well tolerated throughout; participants did not report increases in bowel discomfort vs. placebo

Benefits of Solnul® Demonstrated by This Study

Based directly on the secondary analysis findings, Solnul® was shown to:
✓ Influence gut microbiome composition
✓ Show associations between microbiome changes and participant-reported bowel patterns
✓ Demonstrate individual variability in microbiome responses to prebiotic fiber
✓ Produce microbiome changes independent of overall dietary changes
✓ Be well tolerated with no increases in bowel discomfort vs. placebo

Why This Study Matters

This analysis highlights the complex relationship between the gut microbiome and digestive experiences, demonstrating that prebiotic fibers such as resistant potato starch may influence microbiome-host interactions related to bowel patterns in healthy adults — and that individual microbiome composition may influence the magnitude of response.*

Reference Link: https://pubmed.ncbi.nlm.nih.gov/39605008/

Big-Picture Integration with Other Studies

  • Study 1: A 4-week RCT in 75 healthy adults found that 3.5 g/day Solnul® produced statistically significant increases in Bifidobacterium and Akkermansia and improvements in stool consistency on the Bristol Stool Scale vs. placebo, with tolerability comparable to placebo.
  • Study 2: A 4-week metabolomic analysis found that 3.5 g/day Solnul® influenced circulating free fatty acid profiles and specific secondary bile acid metabolites vs. placebo, with changes associated with microbiome-derived metabolic activity independent of dietary changes.
  • Study 3: A 4-week metabolomic analysis in 48 adults found that 3.5 g/day Solnul® produced ~18% reductions in circulating histamine at week 1, influenced metabolites associated with intestinal barrier metabolism, and showed carnitine changes correlated with Akkermansia increases.
  • Study 4: A 4-week secondary analysis in 70 adults found that Solnul® supplementation was associated with microbiome changes that significantly correlated with participant-reported bowel patterns, independent of dietary changes and with individual variability in responses.

Solnul® Ingredient Summary & Real-World Relevance

Solnul® is a clinically studied resistant potato starch (RS2) designed to support gut health through targeted interactions with the gut microbiome. Unlike many fibers that primarily add bulk, Solnul® is slowly fermented by beneficial microbes and has been studied at doses as low as 3.5 grams per day. Research shows that Solnul® supports the growth of beneficial bacteria such as Bifidobacterium and Akkermansia — two microbes commonly associated with a healthy gut ecosystem.*

Beyond microbiome support, human metabolomic research demonstrates that resistant potato starch may influence circulating metabolites related to fatty acid profiles, bile acid composition, and histamine levels through gut microbiome interactions. These findings highlight the potential role of microbiome-supporting fibers in promoting whole-body wellness through their interactions with the gut microbiota.*

From a practical standpoint, Solnul® is low-FODMAP, generally well tolerated, neutral in taste and texture, and easy to incorporate into daily nutrition. As a whole-food, upcycled resistant starch, it provides a convenient way to support microbiome health as part of a balanced diet.*

Ingredient Manufacturer Link: https://solnul.com/

Solnul® is a clinically studied ingredient used in the following Silver Fern™ Brand products:

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.