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Types of L-Lysine: Forms & Bioavailability

Evidence:Moderate
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Forms Comparison

FormBioavailabilityBest For
L-Lysine HClHighMost common supplemental form; well-absorbed and cost-effective
L-Lysine (free form)HighStandard capsule and tablet formulations

L-Lysine HCl

Bioavailability: High. Best for: Most common supplemental form; well-absorbed and cost-effective.

L-Lysine (free form)

Bioavailability: High. Best for: Standard capsule and tablet formulations.

Find the best L-Lysine for your needs
Ranked by form, bioavailability, and value
Full L-Lysine Guide

References

  1. RCTGriffith RS, Walsh DE, Myrmel KH, et al. (1987). Success of L-lysine therapy in frequently recurrent herpes simplex infection. Dermatologica. DOI PubMed
  2. Civitelli R, Villareal DT, Agnusdei D, et al. (1992). Dietary L-lysine and calcium metabolism in humans. Nutrition. PubMed
  3. RCTSmriga M, Ando T, Akutsu M, et al. (2007). Oral treatment with L-lysine and L-arginine reduces anxiety and basal cortisol levels in healthy humans. Biomedical Research. DOI PubMed
  4. ReviewHayamizu K, Oshima I, Nakano M (2020). Comprehensive Safety Assessment of l-Lysine Supplementation from Clinical Studies: A Systematic Review.. The Journal of nutrition. DOI PubMed
  5. ReviewHayamizu K, Oshima I, Fukuda Z, Kuramochi Y, et al. (2019). Safety assessment of L-lysine oral intake: a systematic review.. Amino acids. DOI PubMed
  6. Meta-analysisFornaro M, Caiazza C, Billeci M, Berk M, et al. (2025). Nutraceuticals and phytoceuticals in the treatment of schizophrenia: a systematic review and network meta-analysis "Nutra NMA SCZ".. Molecular psychiatry. DOI PubMed
  7. Bush JR, Han J, Goodlett DR (2025). Resistant Potato Starch Supplementation Increases Serum Antioxidant Levels in a Randomized Trial.. Metabolites. DOI PubMed
Show 5 more references
  1. Laky B, Huemer D, Eigenschink M, Sagl B, et al. (2024). A Dietary Supplement in the Management of Patients with Lumbar Osteochondrosis: A Randomized, Double-Blinded, Placebo-Controlled Study.. Nutrients. DOI PubMed
  2. Shen S, Liu X, Huang J, Sun Y, et al. (2024). Efficacy of a mouthwash containing ε-poly-L-lysine, funme peptides and domiphen in reducing halitosis and supragingival plaque: a randomized clinical trial.. BMC oral health. DOI PubMed
  3. Schön C, Micka A, Gourineni V, Bosi R (2024). Superior bioavailability of EPA and DHA from a L-lysine salt formulation: a randomized, three-way crossover study.. Food & nutrition research. DOI PubMed
  4. Tsikas D, Maassen N, Thorns A, Finkel A, et al. (2022). Short-Term Supplementation of Sodium Nitrate vs. Sodium Chloride Increases Homoarginine Synthesis in Young Men Independent of Exercise.. International journal of molecular sciences. DOI PubMed
  5. Hong J, Kim HS, Do S, Kim HJ, et al. (2021). Effects of Lysine Cell Mass Supplementation as a Substitute for L-Lysine·HCl on Growth Performance, Diarrhea Incidence, and Blood Profiles in Weaning Pigs.. Animals : an open access journal from MDPI. DOI PubMed