ImmunoLin® - Clinical Research Data Summary

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ImmunoLin® Serum-Derived Bovine Immunoglobulin/Protein Isolate (SBI)

ImmunoLin® is a clinically studied ingredient used in the following Silver Fern™ Brand product:

Introduction

ImmunoLin® is a protein-based dietary ingredient composed of serum-derived bovine immunoglobulin/protein isolate (SBI), delivering a concentrated source of bioactive proteins that support digestive health and mucosal immune function. Containing over 50% immunoglobulins within a >90% protein matrix, ImmunoLin® works within the intestinal lumen by binding certain microbial components — such as endotoxins and other compounds naturally present in the gut — helping to reduce their interaction with the intestinal lining.*

This mechanism supports gut barrier integrity, promotes a balanced intestinal environment, and helps maintain normal immune activity without disrupting beneficial microbiota. Manufactured in an FDA-inspected facility and designated GRAS for use as a dietary ingredient, ImmunoLin® is well tolerated and offers a dairy-free alternative to colostrum-derived ingredients.*

Unlike many digestive ingredients that rely on fermentation or broad antimicrobial activity, ImmunoLin® works within the gut environment to support balance through targeted interaction with microbial components.*

These are the studies for ImmunoLin®. 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://pmc.ncbi.nlm.nih.gov/articles/PMC4020402/
  2. Summary of Study 2 – Full Study: https://pmc.ncbi.nlm.nih.gov/articles/PMC6207257/
  3. Summary of Study 3 – Full Study: https://pubmed.ncbi.nlm.nih.gov/15817854/
  4. Summary of Study 4 – Full Study: https://pmc.ncbi.nlm.nih.gov/articles/PMC5147394/
  5. Summary of Study 5 – Full Study: https://www.mdpi.com/2076-2607/11/3/659
  6. Summary of Study 6 – Full Study: https://pubmed.ncbi.nlm.nih.gov/28275113/
  7. Summary of Study 7 – Full Study: https://pubmed.ncbi.nlm.nih.gov/23660579/
  8. Summary of Study 8 – Full Study: https://pubmed.ncbi.nlm.nih.gov/9327366/

Ingredient Manufacturer Link: https://phb1.com/product/immunolin/



Study 1 Summary

Complete Study Information: https://pmc.ncbi.nlm.nih.gov/articles/PMC4020402/

Clinical Evaluation of Serum-Derived Bovine Immunoglobulin (SBI) in Gastrointestinal Function
Wilson et al. Clinical Medicine Insights: Gastroenterology. 2013.

This randomized, double-blind, placebo-controlled trial evaluated the effects of oral SBI (5 g/day or 10 g/day) vs. soy protein isolate placebo in 66 adults (ages 18–65) experiencing frequent loose stools and gastrointestinal discomfort over 6 weeks, assessing symptom frequency, severity, and quality of life (modified IBS-36 questionnaire).

Study Design Highlights

  • Study design: Randomized, double-blind, placebo-controlled
  • Participants: 66 adults (ages 18–65) with frequent loose stools and GI discomfort
  • Groups: 10 g/day SBI, 5 g/day SBI (with soy protein to match total protein), placebo (soy protein)
  • Duration: 6 weeks
  • Outcomes: Symptom frequency/severity (abdominal discomfort, stool consistency, bloating, gas, urgency), modified IBS-36 quality of life

Key Findings (What the Study Showed)

  • 10 g/day SBI: Statistically significant within-group reductions in abdominal discomfort, loose stools, bloating and gas, urgency, and overall digestive symptom days
  • 5 g/day SBI: Improvements in select measures including gas, incomplete evacuation, and overall symptom frequency
  • No meaningful improvements observed in the placebo group
  • Dose-response effect: improvements more consistent and broader at 10 g/day vs. 5 g/day
  • Well tolerated across all groups; adverse events similar to placebo; no clinically meaningful changes in laboratory safety markers; no serious adverse events

Benefits of ImmunoLin® Demonstrated by This Study

Based directly on the clinical outcomes, SBI was shown to:
✓ Support improved stool consistency and digestive comfort
✓ Support reduction in frequency of common digestive disturbances
✓ Demonstrate a dose-dependent response (10 g > 5 g)
✓ Be safe and well tolerated over 6 weeks comparable to placebo

Why This Study Matters

This randomized, double-blind, placebo-controlled trial demonstrates that targeted immunoglobulin-based nutrition can support multiple aspects of gastrointestinal function. Rather than acting as a general protein source, SBI supported digestive comfort across multiple domains — reflecting its role in maintaining gut barrier integrity and normal immune activity within the gut environment.*

Reference Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC4020402/



Study 2 Summary

Complete Study Information: https://pmc.ncbi.nlm.nih.gov/articles/PMC6207257/

Clinical Evaluation of Serum-Derived Bovine Immunoglobulin (SBI) in Pediatric Digestive Health
Arrouk et al. Pediatric Health, Medicine and Therapeutics. 2018.

This randomized, double-blind, placebo-controlled pediatric pilot study evaluated oral SBI (10 g/day — 5 g twice daily) vs. hydrolyzed gelatin placebo in 15 completing participants (ages 8–18) with frequent loose stools and GI discomfort over 3 weeks, assessing stool frequency, abdominal discomfort, stool consistency (Bristol Stool Scale), functional daily activity (FDI), and digestive quality of life (PedsQOL GI module).

Key Findings (What the Study Showed)

  • Improvements in abdominal discomfort observed by week 3 in the SBI group; no meaningful improvements in placebo
  • Improvements in stool consistency toward more normal form in the SBI group
  • SBI associated with reductions in bowel movement frequency during the first two weeks of use
  • Significant improvements in functional daily activity (FDI scores) in the SBI group vs. placebo
  • Significant improvements in digestive quality of life (PedsQOL) across physical comfort, eating-related discomfort, and overall well-being
  • No serious adverse events; all laboratory safety markers within normal ranges; well tolerated in pediatric population

Benefits of ImmunoLin® Demonstrated by This Study

Based directly on the clinical outcomes, SBI was shown to:
✓ Support improved digestive comfort in children and adolescents ages 8–18
✓ Support healthier stool consistency
✓ Improve functional daily activity scores
✓ Improve digestive quality of life across multiple domains
✓ Be safe and well tolerated in a pediatric population

Why This Study Matters

This study demonstrates that SBI can support multiple aspects of gastrointestinal function in a pediatric population — including comfort, stool consistency, and daily well-being — within a short intervention period, without pharmacological approaches.*

Reference Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC6207257/



Study 3 Summary

Complete Study Information: https://pubmed.ncbi.nlm.nih.gov/15817854/

Clinical Evaluation of Bovine Serum Immunoglobulin on Lipid Metabolism
Earnest et al. American Journal of Clinical Nutrition. 2005.

This randomized, double-blind, placebo-controlled trial evaluated 5 g/day bovine serum immunoglobulin (bIg) vs. hydrolyzed gelatin placebo in 52 adults (ages 25–70) with elevated cholesterol not using lipid-lowering medications over 6 weeks, assessing total cholesterol, LDL, HDL, VLDL, triglycerides, fasting glucose, and liver/kidney/muscle markers.

Key Findings (What the Study Showed)

  • Statistically significant changes in total cholesterol in the bIg group over 6 weeks compared to baseline, with differences vs. placebo by study end
  • Observed changes were largely driven by reductions in LDL cholesterol over time
  • No significant changes in HDL, triglycerides, VLDL, fasting glucose, or liver/kidney function markers
  • Well tolerated; no serious adverse events; compliance similar between groups; no clinically meaningful changes in safety laboratory markers

Why This Study Matters

This study demonstrates that orally administered immunoglobulin proteins can remain functionally active within the gastrointestinal environment and influence systemic physiology through gut-mediated pathways — supporting the concept of a localized, gut-directed mechanism with selective effects on lipid-related markers.*

Reference Link: https://pubmed.ncbi.nlm.nih.gov/15817854/



Study 4 Summary

Complete Study Information: https://pmc.ncbi.nlm.nih.gov/articles/PMC5147394/

Absorption, Digestibility, and Safety of Serum-Derived Bovine Immunoglobulin (SBI)
Shaw et al. Clinical and Experimental Gastroenterology. 2016.

This randomized, double-blind, placebo-controlled crossover study with open-label extension evaluated the digestibility, safety, and gastrointestinal behavior of SBI in 42 healthy adults (ages 18–69), testing single doses of 5 g, 10 g, and 20 g SBI vs. placebo (crossover phase) followed by a 14-day open-label phase (2.5 g, 5 g, or 10 g twice daily).

Key Findings (What the Study Showed)

1. SBI Provides Absorbable Amino Acids

SBI significantly increased circulating essential amino acids vs. placebo across all dose levels, with total amino acids increasing at moderate and higher doses and tryptophan increasing at all doses — confirming SBI's nutritional contribution as a high-quality protein source.

2. Immunoglobulins Remain Partially Intact Through the GI Tract

Intact bovine IgG was detected in stool following daily SBI intake, with levels increasing over time — demonstrating that a portion of SBI's immunoglobulin fraction resists complete digestion and remains active within the intestinal environment.

3. No Systemic Absorption of Bovine IgG

Bovine IgG was not detected in plasma following single or repeated dosing — confirming SBI's immunoglobulins remain within the gastrointestinal tract and do not enter systemic circulation.

4. Safety and Tolerability

No serious adverse events; reported effects mild and primarily digestive in nature; no dose-dependent increase in adverse events; all laboratory safety markers within normal ranges; well tolerated even at doses above typical use.

Benefits of ImmunoLin® Demonstrated by This Study

Based directly on the clinical outcomes, SBI was shown to:
✓ Provide absorbable essential amino acids as a high-quality protein source
✓ Deliver immunoglobulins that remain partially intact and active within the gut
✓ Operate locally within the gastrointestinal tract without systemic IgG exposure
✓ Be safe and well tolerated across a range of intake levels including doses exceeding typical use

Why This Study Matters

This study establishes the foundational mechanism that makes SBI unique: it delivers digestible protein nutrition while simultaneously providing bioactive immunoglobulins that remain active within the gut lumen — supporting a dual-function, gut-local mode of action.*

Reference Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC5147394/



Study 5 Summary

Complete Study Information: https://www.mdpi.com/2076-2607/11/3/659

Effects of Serum-Derived Bovine Immunoglobulin (SBI) on the Human Gut Microbiome and SCFA Production
Van den Abbeele et al. Microorganisms. 2023.

This ex vivo study evaluated SBI, bovine plasma (BP), and albumin-enriched bovine plasma (ABP) at a simulated 5 g/day human intake in the SIFR® (Systemic Intestinal Fermentation Research) model using fecal samples from 6 healthy adult donors, following standardized INFOGEST 2.0 oral/gastric/small-intestinal digestion simulation.

Key Findings (What the Study Showed)

  • SBI significantly increased production of acetate, propionate, and butyrate (short-chain fatty acids) — observed across all 6 donor microbiomes
  • SCFA increases remained higher than comparator protein fractions even after simulated digestion and absorption
  • SBI consistently supported the growth and activity of specific gut microbes associated with SCFA production, with microbial changes strongly correlated with SCFA outcomes
  • Total bacterial cell density increased while overall microbial diversity was preserved — reflecting a balanced shift rather than broad disruption
  • Unlike carbohydrate-based fibers, SBI influenced microbial activity through protein-based pathways engaging a distinct subset of gut microbes

Why This Study Matters

This ex vivo study provides mechanistic evidence that SBI can act as a functional substrate for microbial metabolism, supporting production of short-chain fatty acids associated with normal gut physiology — through a protein-based mechanism distinct from traditional fiber-based prebiotic approaches.*

Reference Link: https://www.mdpi.com/2076-2607/11/3/659



Study 6 Summary

Complete Study Information: https://pubmed.ncbi.nlm.nih.gov/28275113/

Mechanistic Evaluation of Serum-Derived Bovine Immunoglobulin (SBI) on Digestive Function and Gut Physiology
Valentin & Camilleri et al. Physiological Reports. 2017. (Mayo Clinic)

This open-label, single-arm mechanistic study at the Mayo Clinic evaluated SBI (10 g/day — 5 g twice daily) over 8 weeks in 15 adults experiencing frequent loose stools and GI discomfort. The study was designed to explore multiple gut physiology mechanisms rather than establish definitive clinical outcomes, including intestinal environment markers, mucosal gene expression, bile acid–related markers, tryptophan metabolism, and microbiome composition.

Key Findings (What the Study Showed)

  • After 8 weeks: reduced number of daily bowel movements, improved ease of stool passage, reduced sensation of incomplete evacuation
  • Markers related to intestinal permeability and mucosal gene expression remained largely unchanged — suggesting localized functional interactions rather than broad structural changes
  • Exploratory subgroup analyses showed signals of changes in bile acid–related markers in certain individuals, suggesting variability in response based on baseline physiology
  • No significant changes in stool microbiome composition; small localized shifts observed in upper intestinal microbiome — suggesting more direct activity within the small intestinal environment
  • No serious adverse events; well tolerated over 8 weeks

Why This Study Matters

This Mayo Clinic mechanistic study provides valuable insight showing that SBI supports digestive function without requiring broad disruption of the microbiome or large systemic changes — highlighting a targeted, gut-focused approach with individual variability in gut physiology responses.*

Reference Link: https://pubmed.ncbi.nlm.nih.gov/28275113/



Study 7 Summary

Complete Study Information: https://pubmed.ncbi.nlm.nih.gov/23660579/

Effects of Serum-Derived Bovine Immunoglobulin (SBI) on Digestive Function, Nutrient Absorption, and Gut Immune Markers
Asmuth et al. AIDS. 2013.

This open-label human clinical study evaluated SBI (5 g/day — 2.5 g twice daily) over 8 weeks with 4-week washout (and optional long-term extension) in 8 adults experiencing persistent loose stools and digestive dysfunction, assessing gut-associated immune cell markers via duodenal biopsies, bowel function, stool consistency, and intestinal absorptive capacity.

Key Findings (What the Study Showed)

  • Improvements in daily bowel movements, stool consistency toward more normal form, and reductions in urgency and nighttime disturbances; improvements sustained in individuals continuing long-term use
  • Markers of immune cell presence within the intestinal lining increased over the study period — suggesting localized support of gut-associated immune function within the gut environment (not systemic circulation)
  • Measures of carbohydrate absorption improved in most participants, indicating enhanced functional capacity of the small intestine
  • Biomarkers associated with intestinal cell integrity and inflammatory signaling showed patterns consistent with improved intestinal environment over time
  • No serious adverse events; high compliance; well tolerated over both short- and longer-term use

Benefits of ImmunoLin® Demonstrated by This Study

Based directly on the findings, SBI was shown to:
✓ Support improved bowel regularity and stool consistency
✓ Support localized gut-associated immune cell activity
✓ Support enhanced markers of carbohydrate absorption
✓ Support intestinal cell integrity markers
✓ Be well tolerated including extended use

Why This Study Matters

This study demonstrates SBI's ability to support multiple gut functions simultaneously — digestion, absorption, and localized immune activity — even under demanding physiological conditions, reinforcing the gut-directed, multi-pathway nature of SBI's activity.*

Reference Link: https://pubmed.ncbi.nlm.nih.gov/23660579/



Study 8 Summary

Complete Study Information: https://pubmed.ncbi.nlm.nih.gov/9327366/

Safety, Digestibility, and Tolerability of Bovine Serum Proteins in Pediatric Nutrition
Lembcke et al. Journal of Pediatric Gastroenterology & Nutrition. 1997.

This randomized, masked crossover feeding study evaluated bovine serum–derived proteins in 10 young children (ages 9–25 months) across three 7-day dietary periods (standard diet, 25% protein replaced by bovine serum proteins, and 50% protein replaced by bovine serum proteins), assessing diet acceptability, stool frequency/consistency, macronutrient digestion, nitrogen utilization, intestinal permeability, and clinical safety markers.

Key Findings (What the Study Showed)

  • All participants consumed the full diets; no evidence of intolerance or digestive discomfort; stool frequency and consistency remained within normal ranges
  • Nitrogen absorption and retention maintained across all diets — no impairment in protein utilization with bovine serum inclusion
  • At higher inclusion levels, diets with bovine serum proteins were associated with improved absorption of dietary fat and energy
  • Intestinal permeability remained unchanged; clinical laboratory markers within normal ranges throughout

Why This Study Matters

This foundational study demonstrates that bovine serum–derived proteins are safe, effectively digested, and well tolerated even in young children — providing the foundational safety and digestibility evidence supporting bovine serum protein ingredients across all ages.*

Reference Link: https://pubmed.ncbi.nlm.nih.gov/9327366/

Big-Picture Integration with Other Studies

  • Study 1: 6-week RCT in 66 adults showing dose-dependent improvements in digestive comfort, stool consistency, and symptom frequency at 5–10 g/day SBI vs. placebo, with good tolerability.
  • Study 2: Pediatric 3-week RCT in 15 participants (ages 8–18) showing improvements in abdominal discomfort, stool consistency, functional activity scores, and digestive quality of life vs. placebo.
  • Study 3: 6-week RCT in 52 adults demonstrating statistically significant changes in total and LDL cholesterol at 5 g/day bIg vs. placebo, supporting gut-mediated systemic activity.
  • Study 4: Crossover study establishing SBI's dual-function mechanism — digestible protein source (increased plasma amino acids) + bioactive immunoglobulins remaining active in the gut (IgG detected in stool, not plasma).
  • Study 5: Ex vivo SIFR® model demonstrating SBI significantly increases acetate, propionate, and butyrate production across 6 donor microbiomes through a protein-based prebiotic mechanism.
  • Study 6: Mayo Clinic mechanistic study showing SBI supports bowel function improvements with localized activity (no broad microbiome changes, signals in bile acid and upper intestinal pathways).
  • Study 7: Open-label study demonstrating SBI supports bowel regularity, gut-associated immune cell markers, carbohydrate absorption, and intestinal cell integrity — even under demanding physiological conditions.
  • Study 8: Foundational 1997 pediatric crossover study demonstrating bovine serum proteins are safe, well tolerated, and effectively utilized even in children ages 9–25 months.

ImmunoLin® Ingredient Summary & Real-World Relevance

ImmunoLin® (SBI) represents a distinct approach to supporting digestive health. Rather than relying on rapid fermentation, broad antimicrobial activity, or gut motility stimulation, SBI works within the intestinal lumen by interacting with microbial components and supporting a balanced gut environment.*

Supported by 8 studies — including multiple randomized controlled trials in adults and children — SBI has been shown to support digestive comfort and bowel regularity, promote healthy stool consistency, support beneficial microbial metabolic activity and SCFA production, contribute to normal nutrient utilization, and support localized gut-associated immune activity.*

What differentiates SBI is its dual-function mechanism: it delivers digestible essential amino acids while simultaneously providing bioactive immunoglobulins that remain active within the gut environment without entering systemic circulation. It is non-systemic in activity, dairy-free, GRAS-designated, and well tolerated — including in sensitive populations.*

Ingredient Manufacturer Link: https://phb1.com/product/immunolin/

ImmunoLin® is a clinically studied ingredient used in the following Silver Fern™ Brand product:

*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.