Benefits
Cognitive function support — memory, attention, mental focus
Stohs 2022 (, Molecules) review of silk FEH cognitive trials concluded: 'Silk fibroin enzyme hydrolysates exhibit beneficial cognitive effects with respect to memory and learning, attention, mental focus, accuracy, memory recall, and overall memory and concentration.' Studies span children (7+ years), high school/college students, adults, and seniors (up to 92 years). Doses 200-600 mg/day for 3-16 weeks. Yi 2017 placebo-controlled RCT specifically investigated silk fibroin enzymatic hydrolysate on memory improvement with positive results.
Modest athletic stamina effect (small trial)
RCT in elite fin-swimmers showed silk amino acid supplementation improved physiological parameters defining stamina. Mechanism speculatively involves serine/glycine effects on creatine pool, mild neurotransmitter effects, or combined amino acid contributions. Single small specialized population trial — generalizability limited.
Skin hydration and barrier (sericin oral and topical)
Kim 2012 mouse study (animal evidence) showed dietary silk protein/sericin improved epidermal hydration with increased filaggrins and free amino acids. Limited human translation but cosmetic industry uses sericin in topical hydrating formulations with empirical support. Skin benefits are weaker evidence than cognitive benefits.
Glucose and lipid profile improvements (animal evidence)
Jung 2010 in diabetic mice showed silk protein hydrolysates improved blood glucose and lipid profiles. Limited human RCT evidence for these metabolic effects. Animal data interesting but translation to humans not yet rigorously demonstrated.
Mechanism of action
Acetylcholine pathway support (cognitive effects)
Mechanistic studies suggest silk FEH supports cholinergic neurotransmission — acetylcholine is released by cholinergic neurons and plays a key role in encoding new information and learning. Mechanism may involve choline supply enhancement or acetylcholinesterase modulation. Supports the cognitive benefit observations across multiple human trials.
Antioxidant and neuroprotective activity
Silk fibroin and sericin demonstrate antioxidant activity (radical scavenging, GSH support) and reduce neuroinflammation in cell and animal models. May contribute to cognitive benefits via neuroprotection — particularly relevant for aging-related cognitive decline. Mechanism comparable to other dietary antioxidants but with some unique sequence-specific peptide effects.
Glycine and alanine high-concentration delivery
Silk fibroin's distinctive amino acid profile — ~43% glycine and ~30% alanine — provides high-dose glycine delivery from a relatively small mass. Glycine has independent CNS effects (NMDA co-agonist, glycine receptor agonist, sleep quality support). Alanine contributes to glucose-alanine cycle and possibly modest performance effects. The unique amino acid profile distinguishes silk from typical dietary proteins.
Anti-inflammatory peptide activity
Silk fibroin peptides demonstrate anti-inflammatory effects in vitro and in animal models — modulating NF-κB and reducing pro-inflammatory cytokines. May contribute to neuroprotective and skin-protective effects observed.
Clinical trials
Comprehensive review (Stohs SJ, Bucci LR 2022, Molecules 27(17):5407, doi:10.3390/molecules27175407). PMC9457898.
Review of all known PubMed and Google Scholar studies on silk fibroin enzyme hydrolysates (FEH) and cognitive function. Studies in children, high school/college students, adults, and seniors (ages 7-92). Doses 200-600 mg silk FEH per day for 3-16 weeks.
Silk FEH demonstrate beneficial cognitive effects on memory, learning, attention, mental focus, accuracy, memory recall, and overall memory/concentration across multiple trials. Mechanism involves neuroprotection via antioxidant and inflammation-inhibiting activities. Acetylcholine pathway involvement supports cholinergic encoding of new information. Most authoritative review of silk cognitive evidence base.
Placebo-controlled double-blind study (Yi JK, Park JM, Kim HS, Kim SS, Lee SP, Yang JE, Lee KS, Cho M, Lee HK, Park J, Sohn UD 2017). PMC5852809.
Healthy individuals randomized to silk fibroin protein enzymatic hydrolysate (FPEH) or placebo. Cognitive memory tests at baseline and follow-up.
FPEH ingestion improved memory function compared to placebo. Demonstrated specificity to enzymatic hydrolysate of silkworm fibroin (MW 500-5,000 Da). Glycine, alanine, serine, tyrosine comprise >90% of fibroin protein — amino acid mix relevant to neurotransmitter synthesis and neuroprotection. One of multiple trials supporting cognitive benefits of silk FEH.
Trial in elite athletes (Park 2014, related publications PMID 25525417 — citation context).
Elite fin-swimmers receiving silk amino acid supplementation vs control. Outcomes: physiological parameters defining stamina including blood lactate, performance markers.
Silk amino acid supplementation improved physiological parameters defining stamina in this elite athlete population. Limited generalizability due to specialized cohort and study design constraints. Provides supportive evidence for athletic application but not as strong as the cognitive evidence base.