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Ly7.0
L-Lysine Research
Likely helpsHigh safety
24 peer-reviewed studies
What the evidence says
Likely helps
L-Lysine appears to help in 7 of 9 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1987–2025 with a typical study size of 60 participants.
Based on 24 studies · 2 meta-analyses · 13 RCTs · 3,340 total participants
Confidence
High
What the studies found
7helped2unclear· 15 more without graded effect data
By outcome
Glucose & metabolic
Likely helps9 studies
Therapeutic & clinical
Mostly mechanism / observational6 studies
Digestive health
Mixed evidence5 studies
Safety profile
Mixed evidence5 studies
Cold sores & HSV
Mostly mechanism / observational4 studies
Anxiety & stressReduces cortisol and anxiety in lysine-deficient populations · 2-4 weeks
Mostly mechanism / observational3 studies
Bone healthSupports bone mineral density and skeletal strength · 8-12 weeks
Too few graded studies2 studies
Skin health
Too few graded studies1 study
Heart & blood pressure
Too few graded studies1 study
Vision & eye health
Too few graded studies1 study
By the numbers
Pulled from 18 studies with measurable effects
Likely real effects
71%
across studies
People studied
3,340
typical study: 60 people
Strongest designs
15
2 pooled, 13 randomised
Showed benefit
78%
7/9 studies
How long studies ran
Under a week
2
1–4 weeks
2
1–3 months
1
3+ months
3
Populations Studied
Patients with schizophrenia2
General population2
Healthy participants and T2DM/obese individuals1
Individuals with anxiety and anxiety-related conditions1
Steady research
6 studies in the last 5 years · Latest meta-analysis: 2025
198720062025
1Total symptomatologyMeta-AnalysisCited 10×n=50 · small study2025
Fornaro M et al. · Molecular psychiatry (2025)
Large benefit
← WorseNo effectBetter →
Change (Standardized Mean Difference = SMD) in total symptomatology and acceptability (Risk Ratio = RR) were co-primary outcomes.
High heterogeneity (tau2 = 0.10, I2 = 55.9%) and global inconsistency (Q = 40.79, df = 18, p = 0.002) emerged without publication bias (Egger's test, p = 0.42).
2Postprandial glucose and insulin response to amino acidsSystematic ReviewCited 23×n=55 · small study2020
The extracted information is publicly available and can serve multiple purposes such as computational modeling.
Sloun BV et al. · Nutrients (2020)
Oral ingestion of most individual AAs induced an insulin response, but did not alter glucose concentrations in healthy participants.
Specific AAs (i.e., leucine and isoleucine) co-ingested with glucose exerted a synergistic effect on the postprandial insulin response and attenuated the glucose response compared to glucose intake alone in healthy participants.
Oral AA ingestion as well as intravenous AA infusion was able to stimulate an insulin response and decrease glucose concentrations in T2DM and obese individuals.
3Risk of gastrointestinal symptomsSystematic ReviewCited 23×n=71 · small study2019
Integrated analysis of the risk for developing gastrointestinal symptoms revealed that the risk ratio was 1.02 (95% CI, 0.96-1.07; p = 0.49); thus, no significant increase was observed. (UMIN000028914).
Hayamizu K et al. · Amino acids (2019)
No clear effect
← WorseNo effectBetter →
Could be chance
Integrated analysis of the risk for developing gastrointestinal symptoms revealed that the risk ratio was 1.02 (95% CI, 0.96-1.07; p = 0.49); thus, no significant increase was observed. (UMIN000028914).
The dose range of L-lysine in the selected studies was 16.8-17,500 mg/day, and the range of dosing period was 1-1095 days.
The observed adverse events were mainly subjective symptoms related to the gastrointestinal tract such as nausea, stomachache, and diarrhea.
4Anxiety and anxiety-related conditionsSystematic ReviewCited 98×n=2,619 · very large study2010
Based on the available evidence, it appears that nutritional and herbal supplementation is an effective method for treating anxiety and anxiety-related conditions without the risk of serious side effects.
Lakhan SE et al. · Nutrition journal (2010)
Huge benefit
← WorseNo effectBetter →
Of the randomized controlled trials reviewed, 71% (15 out of 21) showed a positive direction of evidence.
Based on the available evidence, it appears that nutritional and herbal supplementation is an effective method for treating anxiety and anxiety-related conditions without the risk of serious side effects.
There is the possibility that any positive effects seen could be due to a placebo effect, which may have a significant psychological impact on participants with mental disorders.
5Safety of l-Lysine supplementationSystematic ReviewCited 17×2020
The provisional no-observed-adverse-effect level in healthy human subjects was based on gastrointestinal symptoms and identified at 6.0 g/d.
Hayamizu K et al. · The Journal of nutrition (2020)
No clear effect
← WorseNo effectBetter →
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).
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.
Doses >3g/day improved patients' subjective disease experience; <1g/day was ineffective.
Mailoo VJ et al. · Integrative Medicine (2017)
Higher doses (>3g) more effective
Low doses (<1g) ineffective
Best combined with low-arginine diet
7Lumbar disc volume changesRCTCited 1×2024
In conclusion, this multi-nutrient supplement might not only stabilize the progression of lumbar osteochondrosis, but it might also potentially even increase IVD volumes as detected on MRIs.
Laky B et al. · Nutrients (2024)
Noticeable benefit
← WorseNo effectBetter →
Likely real
Despite no significance regarding the distribution of Pfirrmann grade changes (improvement, no change, worsening; p = 0.259), in the supplement group, one patient achieved a three-grade improvement, and worsening of Pfirrmann grades were only detected in the placebo group (9.1%).
Disc degeneration according to Pfirrmann classifications remained stable during the 3-month intervention in both groups.
Furthermore, in-depth evaluations of MRIs showed significantly higher 3D-measured volume changes (increase) in the supplement (+740.3 ± 796.1 mm3) compared to lower 3D-measured volume changes (decrease) in the placebo group (-417.2 ± 875.0 mm3; p < 0.001).
9Postprandial glucose iAUC0-120minRCTCited 5×n=60 · small study2020
Future studies should clarify, whether regular consumption of the supplement improves markers of disease or could play a role in a diet aiming at preventing the development of diabetes.
Östman E et al. · PloS one (2020)
Noticeable benefit
← WorseNo effectBetter →
Likely real
In the intention-to-treat-analysis (n = 60) the supplement resulted in a decreased venous blood glucose iAUC0-120min compared to placebo, mean (SE) of 68.7 (6.6) versus 52.2 (6.8) respectively, a difference of -16.5 mmol/L•min (95% CI -3.1 to -30.0, p = 0.017).
The Cmax for venous blood glucose for the supplement and placebo were 6.45 (0.12) versus 6.10 (<0.12), respectively, a difference of -0.35 mmol/L (95% CI -0.17 to -0.53, p<0.001).
In the per protocol-analysis (n = 48), the supplement resulted in a decreased Cmax compared to placebo from 6.42 (0.14) to 6.12 (0.14), a difference of -0.29 mmol/L (95% CI -0.12 to -0.47, p = 0.002).
10Visual discomfort from vitreous floatersRCTCited 6×n=61 · small study2021
The findings of this study indicate improvements in vision-related quality of life and visual function of patients suffering from vitreous floaters after supplementation with a formulation of antioxidative and antiglycation micronutrients.
Ankamah E et al. · Translational vision science & technology (2021)
Likely real
After supplementation, the active group reported a significant decrease in their visual discomfort from floaters (P < 0.001), whereas the placebo group had no significant change in their visual discomfort (P = 0.416).
At 6 months, there was a significant decrease in vitreous opacity areas in the active group (P < 0.001) and an insignificant increase in vitreous opacity areas in the placebo group (P = 0.081).
Also, there was a significant improvement in photopic functional contrast sensitivity with positive contrast polarity in the active group after supplementation (P = 0.047).
12Blood glucose responseRCTCited 10×n=7 · very small study2017
This trial was registered at www.anzctr.orgau as 12614000837628.
Ullrich SS et al. · The Journal of nutrition (2017)
Noticeable benefit
← WorseNo effectBetter →
Likely real
Lysine did not affect blood glucose at 15 min or the blood glucose area under the curve from 0 to 60 min (AUC0-60min) but it decreased blood glucose at 60 min compared with the control solution (-9.1% ± 3.1%, P < 0.01).
Similarly, the early insulin response and insulin AUC0-60min were not affected by lysine, but plasma insulin at 60 min was 20.9% ± 5.6% lower than after the control (P < 0.05).
Plasma glucagon at both 15 min (20.7% ± 4.7%, P < 0.001) and 60 min (14.1% ± 5.4%, P < 0.05) and the glucagon AUC0-60min (P < 0.01) were greater after lysine than after the control.
Structure and function of glycated lysozyme are significantly improved by l-lysine; therefore it can be considered an effective therapeutic supplementation in T2DM, decreasing the risk of infection in these patients.
Mirmiranpour H et al. · Acta medica Iranica (2016)
Structure and function of glycated lysozyme are significantly improved by l-lysine; therefore it can be considered an effective therapeutic supplementation in T2DM, decreasing the risk of infection in these patients.
The quantity and activity of lysozyme and other parameters were then measured.
Among the test group, L-lysine was found to reduce the advanced glycation end products (AGEs) in the sera of patients with T2DM and in vitro condition.
14Calcium absorptionRCTCited 16×n=14 · very small study2014
Larger and longer clinical trials are needed to clarify the possible benefit of arginine and lysine on calcium absorption.
Bihuniak JD et al. · The Journal of nutrition (2014)
Barely noticeable benefit
← WorseNo effectBetter →
Could be chance
There was no difference in calcium absorption between the diet supplemented with CaSR-AAAs (22.9 ± 2.0%) and the control diet (22.3 ± 1.4%) (P = 0.64).
However, calcium absorption tended to be greater during the DAA supplementation period (25.2 ± 1.4%) compared with the control diet period (22.3 ± 1.4%) (P < 0.10).
Intestinal calcium absorption was measured between days 5 and 6 using dual-stable calcium isotopes ((42)Ca, (43)Ca, and (44)Ca).
16Body cell mass and lean massRCTCited 97×n=39 · small study2009
Consumption of a simple amino acid-related cocktail increased protein turnover and lean tissue in elderly individuals in a year-long study.
Baier S et al. · JPEN. Journal of parenteral and enteral nutrition (2009)
Barely noticeable benefit
← WorseNo effectBetter →
Likely real
Compared with control, HMB/Arg/Lys increased body cell mass (BIA) by 1.6% (P=.002) and lean mass (DXA) by 1.2% (P=.05).
The rates of protein turnover were significantly increased 8% and 12% in the HMB/Arg/Lys-supplemented group while rates of protein turnover decreased 11% and 9% in the control-supplemented subjects (P<.01), at 3 and 12 months, respectively.
Consumption of a simple amino acid-related cocktail increased protein turnover and lean tissue in elderly individuals in a year-long study.
Such action may represent a normalization of hormone levels to the pattern observed previously in subjects with low trait anxiety.
Jezova D et al. · Nutritional neuroscience (2005)
Amino acid treatment resulted in enhanced adrenocorticotropic hormone, cortisol, adrenaline and noradrenaline levels and galvanic skin responses during stress compared to those in placebo-treated group.
Increases in the heart rate and blood pressure in response to public speaking task were not influenced by amino acid treatment.
Results of the present study support the hypothesis that L-lysine in combination with L-arginine, which may induce anxiolytic effects, modify hormonal responses during psychosocial stress in humans.
19Trait and state anxiety reductionRCTCited 47×n=108 · medium study2007
These results of this double-blind, placebo controlled and randomized study confirm the previous findings in humans and animals and point to a combination of L-lysine and L-arginine as a potentially useful dietary intervention in otherwise healthy humans with high subjective levels of mental stress and anxiety.
Smriga M et al. · Biomedical research (Tokyo, Japan) (2007)
We confirmed that, without regard to gender, the amino acid treatment significantly reduced both trait anxiety and state anxiety induced by cognitive stress battery.
The aim of study was to find out whether a week-long oral treatment with L-lysine (2.64 g per day) and L-arginine (2.64 g per day) reduces trait and stress-induced state anxiety and basal levels of stress hormones.
In addition, we found that the treatment with L-lysine and L-arginine decreased the basal levels of salivary cortisol and chromogranin-A (a salivary marker of the sympatho-adrenal system) in male subjects.