1. Comprehensive Safety Assessment of l-Lysine Supplementation from Clinical Studies: A Systematic Review
Kohsuke Hayamizu, Ikuyo Oshima, Makoto Nakano J Nutr. 2020 Oct 1;150(Suppl 1):2561S-2569S. doi: 10.1093/jn/nxaa218.
Background: Despite the widespread use of l-lysine in dietary supplements, the safety information pertinent to excessive l-lysine ingestion is limited and, to the best of our knowledge, there is no published systematic review of safety. Objective: The objective of this study was to assess the clinical safety of l-lysine supplementation of a regular diet. Methods: We searched PubMed, Cochrane Library, Ichushi Web, and EBSCOhost using the relevant keywords, "l-lysine" and "clinical trial." To investigate all adverse events observed during intervention trials, we included all intervention studies with orally ingested l-lysine without restricting background factors, environment, study designs, and sample sizes. Results: We identified 71 articles, which included 3357 study subjects. The l-lysine doses ranged from 16.8 to 17.5 g/d, and the dosing period ranged from 1 to 1095 d. The observed adverse events were mainly subjective gastrointestinal tract symptoms; however, the risk analysis for incidence of gastrointestinal symptoms was not statistically significant (risk ratio of 1.02). Conclusion: The provisional no-observed-adverse-effect level in healthy human subjects was based on gastrointestinal symptoms and identified at 6.0 g/d. The review protocol was registered at umin.ac.jp as UMIN000028914 before the beginning of the study.
2. L-lysine: Its antagonism with L-arginine in controlling viral infection. Narrative literature review
Maria Cristina Pedrazini, Mariliza Henrique da Silva, Francisco Carlos Groppo Br J Clin Pharmacol. 2022 Nov;88(11):4708-4723. doi: 10.1111/bcp.15444. Epub 2022 Jul 5.
Knowledge about viral characteristics, mechanisms of entry into the host cell and multiplication/dissemination can help in the control and treatment of viral pathologies. Several nutritional factors linked to the host may favour viral multiplication and their control, may lead to new prophylactic alternatives and/or antiviral therapies. The objective of this review is to discuss the relationship between the amino acid L-lysine and the control of viral infections, aiming at a possible therapeutic property. This research used databases such as PubMed, Web of Science, Scielo, Medline and Google Scholar, as well as searching for references cited by journals. The time frame covered the period between 1964 and January 2022. The observed studies have shown that the usual antiviral therapies are not able to interfere with the viruses in their latent state; however, they can interfere with the adhesion and fusion of viral particles or the production of proteins, which play an important role in viral epidemiology and control, particularly in the initial moment and in reactivation. Lysine is an amino acid that can interfere mainly in the formation of capsid proteins and DNA by a competitive antagonism with amino acid arginine, which is an essential amino acid for some viruses, and also by promoting the increase of arginase, increasing the catabolism of arginine. Although there is evidence of the importance of L-lysine in viral control, more studies are needed, with a view to new antiviral therapies.
