Inositol citrulline silicate

Inositol-Stabilized Arginine Silicate (Arginine Silicate Inositol; ASI)

Editorial note on nomenclature: The term "inositol citrulline silicate" does not correspond to any named ingredient in the peer-reviewed scientific literature, regulatory databases, patent records, or pharmacopoeial monographs. Comprehensive database searches — including PubMed/PMC, the U.S. Patent and Trademark Office, the U.S. FDA dietary supplement notifications database, and authoritative evidence sources — return no distinct ingredient by this name. The phrase most likely reflects a confusion or conflation of two distinct but related sports-nutrition concepts: (1) inositol-stabilized arginine silicate (ASI; Nitrosigine®), a well-characterized patented complex of arginine, silicate, and inositol; and (2) L-citrulline, the amino acid that is biochemically produced from arginine during nitric oxide synthesis and is often used alongside ASI in pre-workout formulations. Because citrulline is a downstream metabolite of arginine in the nitric oxide pathway — not a structural constituent of the silicate complex — and because no evidence supports the existence of a separate "inositol citrulline silicate" ingredient, this article documents the verified ingredient: inositol-stabilized arginine silicate (ASI), along with the relevant context of its biochemical relationship to citrulline. All claims below are grounded exclusively in peer-reviewed publications, patent records, and government-linked sources.

1. Identity

1.1 Names and Designations

Inositol-stabilized arginine silicate, otherwise referred to as arginine silicate inositol (ASI), is a novel bioavailable source of arginine, silicon, and inositol. ASI comprises a bonded arginine–silicate complex, stabilized by inositol. Although the compositions generally contain arginine, silicate, and inositol, it may be referred to as "inositol-stabilized arginine silicate," "arginine silicate," "arginine silicate inositol," "ASI," "Nitrosigine®," or simply "the complex."

Common designations in the literature include:

• Inositol-stabilized arginine silicate (ASI) — the scientific name used in peer-reviewed publications
• Arginine silicate inositol (ASI) — an alternative ordering used in some patent documents
• Nitrosigine® — the primary commercial trade name, used in sports-nutrition and exercise contexts
• nooLVL® — a related trade name for a formulation containing ASI combined with additional free inositol, marketed for cognitive (particularly esports/gaming) applications

1.2 Chemical Composition and Synthesis

Although the product contains arginine, silicate, and inositol, it is referred to throughout the specification as "arginine silicate." Arginine silicate is synthesized by reacting arginine (free base), potassium silicate, and inositol. The resulting complex is completely soluble and provides silicate in a bioavailable form. Silicates are typically insoluble in aqueous solutions; however, the use of inositol in the synthesis renders the complex soluble in aqueous solution. Arginine silicate synthesized in the absence of inositol was insoluble in aqueous solutions. This unexpected solubilization effect of inositol is of paramount importance to the use of the complex as a bioavailable source of arginine and silicate. Inositol facilitates solubilization of arginine silicate by increasing hydrogen bonding between arginine and silicic acid.

In a preferred embodiment, the combining molar ratio of arginine to silicate is about 1:1, and the ratio of inositol to arginine and silicate is about 1:3. Although potassium silicate was used as a reactant, the use of other silicate salts, including sodium silicate and magnesium silicate, is also within the scope of the invention.

Inositol, also referred to as myo-inositol, is a carbocyclic sugar that is abundant in the brain and other mammalian tissues. It is known to mediate cell signal transduction in response to a variety of hormones, neurotransmitters, and growth factors. Proton magnetic resonance studies show that oral administration increases inositol levels in the brain. In addition to its physiological functions in the body, inositol also aids in the manufacturing of arginine silicate as it allows for the 1:1 binding of arginine to silicon and prevents the polymerization of silicon.

1.3 Regulatory and GRAS Status

ASI has been affirmed as generally recognized as safe (GRAS) and is marketed in the United States after Food and Drug Administration New Dietary Ingredient Notification under the trade name Nitrosigine®.

1.4 Common Dosage Forms

ASI is commercially available in powdered beverage forms (used in pre-workout drink mixes) and encapsulated forms. Commercial product has been documented to contain arginine, silicon, inositol, and potassium, with excipients including citric acid, natural flavour, sucralose, acesulfame potassium, and Red 40. Capsule formulations are also used: in one published pharmacokinetic study, ten healthy males took three 500 mg arginine silicate capsules (active product) daily for 14 days.

1.5 Relationship to Citrulline

Arginine is the substrate for nitric oxide (NO) synthase, which converts it to citrulline and synthesizes NO in the process. Citrulline is thus a biochemical product of arginine metabolism, not a structural component of ASI. Comparison studies have found that supplementing with L-citrulline, citrulline malate (CM), or inositol-stabilized arginine silicate (ASI) more efficiently elevates serum arginine and serum citrulline. Both ASI and citrulline-based supplements are used in sports nutrition to increase NO production, and they are frequently studied alongside each other, which may contribute to nomenclatural confusion in the popular press.

2. Traditional and Historical Use

Inositol-stabilized arginine silicate (ASI / Nitrosigine®) is an entirely synthetic, patent-derived ingredient. It is described as a novel bioavailable source of arginine, silicon, and inositol. As a specifically engineered complex, it has no traditional or pre-modern history of use in any food culture or herbal medicine system; it does not occur in nature as a discrete compound.

However, the individual constituent raw materials — arginine, inositol, and silicon — each carry their own independent scientific histories:

• L-arginine is a semi-essential amino acid found naturally in foods such as meat, dairy, nuts, and seeds. It was first isolated in 1886 and has been studied as a dietary component and pharmaceutical agent for decades, particularly in cardiovascular research.
• Inositol (myo-inositol) is found naturally in fruits, beans, grains, and nuts and was studied as a B-vitamin-like compound from the early twentieth century, though it is not formally classified as an essential vitamin.
• Silicon, as orthosilicic acid and related silicates, is naturally present in plant-based foods, water, and a variety of antacid and analgesic compounds. Silicon is an abundant trace element found in many plant-based foods as well as many antacids and analgesics. It plays an important role in skin and bone health.

The deliberate ionic bonding of arginine with potassium silicate and inositol into ASI is a modern pharmaceutical/nutraceutical innovation, first described in U.S. patent literature in the 1990s and brought to the commercial market under the Nitrosigine® brand name in the early 2010s. Nitrosigine was announced around 2013, and the quality of research on it has expanded substantially since then.

3. Key Constituents and Active Compounds

3.1 Arginine as the Primary Bioactive

Arginine, a nonessential amino acid, is the substrate for nitric oxide (NO) synthase, which converts it to citrulline and synthesizes NO in the process. Arginine has demonstrated its potential to improve aerobic and resistance exercise performance and recovery due to its ability to increase NO production and subsequent vasodilation.

A longstanding problem with plain L-arginine supplementation is poor oral bioavailability. There is limited evidence to support the efficacy of supplemental L-arginine in cardiovascular disease, partly due to alterations in bioavailability. Results are more promising when L-arginine is combined with other substances, such as silicon, that enhance absorption and bioavailability. It has been demonstrated in rat models that arginine silicate inositol complex is more effective in increasing serum arginine levels than the commonly used arginine hydrochloride.

3.2 Silicon (Silicate) as a Structural and Bioactive Component

Results are more promising when L-arginine is combined with substances such as silicon, that enhance absorption and bioavailability. There is some evidence to suggest that silicon, especially as silicic acid, may protect vascular integrity during age-related vascular diseases.

The effects of arginine and silicon on joint health and connective tissue metabolism in mammals are well documented, and the ASI complex has been shown to benefit bone and vascular health.

3.3 Inositol as Stabilizer and Independent Bioactive

The unexpected solubilization effect of inositol is of paramount importance to the use of the complex as a bioavailable source of arginine and silicate. Inositol facilitates solubilization of arginine silicate by increasing hydrogen bonding between arginine and silicic acid.

Inositol has been reported to enhance neurotransmission and memory. Inositol is known to mediate cell signal transduction in response to a variety of hormones, neurotransmitters, and growth factors. Proton magnetic resonance studies show that oral administration increases inositol levels in the brain.

3.4 Nitric Oxide as the Central Mechanism

Nitric oxide (NO) has been shown to be involved in many physiological processes and to affect several organ systems; it is best known for its role in vasodilation and related cardiovascular health. Vascular dysfunction and damage have been shown to be associated with impaired endothelial NO metabolism and function.

Nitric oxide is a key factor in promoting the relaxation of smooth muscle in blood vessels, increasing blood flow to working muscles. Enhanced NO availability, via arginine administration, induces vasodilation, increases blood flow to the working musculature, improves cardiovascular health, lowers blood pressure, improves exercise performance, and enhances memory. Research also demonstrates that NO may be a prospective therapeutic approach in managing and mitigating mild cognitive impairment due to its mechanistic action, increasing systemic blood flow and, conceivably, cerebral circulation.

3.5 nooLVL® — the Inositol-Enhanced Variant

Inositol-stabilized arginine silicate (ASI) ingestion has been reported to increase nitric oxide levels, while inositol (I) has been reported to enhance neurotransmission. A distinct commercial product, referred to as "inositol-enhanced bonded arginine silicate" (ASI + I), examines whether co-ingesting ASI and additional inositol affects cognitive function in e-sport gamers. One documented formulation of nooLVL® contains 600 mg of arginine, 105 mg of silicon, 385 mg inositol, and 60 mg potassium per 1600 mg dose.

4. Pharmacokinetics

ASI starts to work within 15 minutes of ingesting and significantly increases arginine levels for up to 6 hours.

Fasting blood and saliva collections were performed pre-dose and at 0.5, 1, 1.5, 2, 3, 4, 5, and 6 hours post-dose for plasma arginine, serum silicon, and salivary NO + nitrite. Day 1 pharmacokinetic parameters (adjusted for body weight) for arginine were: peak serum concentration (C_max) 30.06 ± 7.80 µg/mL, time to peak serum concentration (t_max) 1.13 ± 0.52 hours, and half-life (t_1/2) 15.93 ± 9.55 hours; and for silicon: C_max 2.99 ± 0.63 µg/mL, t_max 2.44 ± 2.05 hours, and t_1/2 34.56 ± 16.56 hours.

The arginine silicate dietary supplement increases blood levels of arginine after a single dose within 30 minutes and blood levels of silicon for up to 1.5 hours. Blood levels of arginine, silicon, and NO (salivary nitrite) were elevated consistently after 14 days of use. The observed increase in baseline salivary nitrite is supporting information that there was some improvement in NO production.

After 14 days of use, baseline NO levels increased in six subjects and stayed the same in four subjects; this shift was significant (P = 0.031).

5. Scientific Evidence by Area of Use

5.1 Cardiovascular Function and Vasodilation

Overview: The most extensively studied application of ASI is its effect on nitric oxide production and vascular function (vasodilation and blood flow). Multiple human clinical trials have been conducted in this area.

Pharmacokinetic/pharmacodynamic study (Kalman et al., 2015): Ten healthy males, 26.7 ± 5.4 years, took three 500 mg arginine silicate capsules (active product) for 14 days. The subjects attended test visits on Days 1 and 14. The supplement increased blood levels of arginine after a single dose within 30 minutes, and blood levels of silicon for up to 1.5 hours. Blood levels of arginine, silicon, and NO (salivary nitrite) were elevated consistently after 14 days of use. The observed increase in baseline salivary nitrite was supporting information that there was some improvement in NO production. Within the specific protocol of this study, the product was found to be safe. This was a small (n=10), open-label, single-arm pharmacokinetic study — not placebo-controlled — which limits conclusions about efficacy.

Flow-mediated dilation vs. citrulline malate (Rogers et al., 2020): Healthy, normotensive, and physically active male (n = 16) and female (n = 8) young adults participated. A randomized, double-blind, within-subjects design was used where participants reported for three trials, each preceded by a 7-day washout period. Baseline flow-mediated dilation (FMD) measurement was obtained for each visit, followed by consumption of one clinical dose of citrulline malate (8 g), Nitrosigine (1.5 g), or dextrose placebo (8 g). Following a 60-min digestion period, FMD was repeated. Repeated measures ANOVA yielded a significant supplement × time effect (p < .001), such that both citrulline malate and ASI yielded a greater change in FMD response than placebo. After allometric scaling, the supplement × time effect remained significant (p = .001). Both supplemented conditions increased vascular NO production as measured by a change in FMD and may be particularly beneficial to individuals looking to increase the potential for muscle hyperemia during exercise. This randomized double-blind crossover study is methodologically strong but was conducted on young healthy adults, limiting generalizability.

5.2 Exercise Performance, Muscle Pump, and Recovery

Workout ingredient study (Rood-Ojalvo et al., 2015): The purpose of the study was to examine the benefits of ASI (Nitrosigine®) as a workout ingredient in healthy adults. ASI had been previously shown to significantly enhance blood levels of arginine up to six hours post-dose and increase nitric oxide levels. To investigate reports of enhanced energy, increased muscle pump and stamina during workouts, and faster muscle recovery post-workout, ASI (1,500 mg/day) was tested in a double-blind placebo-controlled crossover study using POMS vigor-activity and fatigue-inertia sub-scores, blood flow measurements, leg circumference measurements, and biomarkers of muscle recovery (creatine kinase (CK) and lactate dehydrogenase (LDH)) as outcome measures.

The DBPC-X study was conducted in male subjects (N = 16 per group) who had limited exercise routines prior to participating. Subjects took ASI daily for 4 days. Subjects had baseline measurements drawn at hour 0, took the study product, and completed an intense leg extension exercise protocol to induce muscle soreness. Subjects returned after 24, 48, and 72 hours for additional study measurements. After 72 hours, subjects repeated the leg extension exercise protocol.

CK levels significantly decreased in the ASI group at 24 (p = 0.040), 48 (p = 0.017), and 72 (p = 0.034) hours post-exercise compared to the placebo group. Immediately post-exercise, ASI supplementation led to 44% less muscle damage, measured by CK levels, than placebo (p = 0.057). LDH levels significantly increased from baseline immediately after exercise in the placebo group (p = 0.015), but not in the ASI group (p = 0.366). No safety concerns were raised by this study.

Both primary and secondary endpoints showed that daily doses of ASI prior to workout significantly increased pre-workout energy levels, increased muscle pump immediately following a workout, and decreased biomarkers of muscle damage immediately after a workout and during recovery. These results demonstrate multiple benefits of ASI as a functional workout ingredient.

A more detailed 2023 replication in the Journal of Exercise and Nutrition (Inositol-stabilized arginine silicate (ASI; Nitrosigine®) significantly increases circulating arginine and nitric oxide. ASI effects on objective and subjective indicators of muscle recovery, blood flow, and energy were examined. In a double-blind, placebo-controlled crossover design, subjects (n = 16) were given ASI (1,500 mg/day) or placebo for 4 days, with a 7-day washout period. Measurements occurred at baseline, 24, 48, and 72 hours; on test days subjects performed stress-inducing leg extension exercises associated with muscle soreness. Following exercise, recovery markers including creatine kinase (CK), myoglobin, and lactate dehydrogenase (LDH), Doppler ultrasound blood flow, leg circumference, and salivary nitrite were measured. Profile of Mood States (POMS), VAS scales, and vigor-activity cognitive tests were also administered. Serum CK, but not LDH, was significantly reduced in the ASI group on day 1 and at 24, 48, and 72 hours post-exercise (p < 0.05); myoglobin was also reduced.

Evidence assessment: The evidence for ASI's effects on acute muscle pump and short-term muscle damage biomarkers is reasonably consistent across small-to-moderate-sized randomized double-blind crossover trials. The studies are methodologically sound but are limited by: small sample sizes (mostly n = 16–24), male-only populations, short intervention periods (3–14 days), and the fact that a number of studies were conducted or funded by the manufacturer (Nutrition 21, LLC).

5.3 Cognitive Function

Trail Making Test studies (Kalman et al., 2016): ASI (Nitrosigine®) has been validated to increase levels of arginine, silicon, and nitric oxide production. To evaluate potential enhancement of mental focus and clarity, ASI (1500 mg/day) was tested in two double-blind placebo-controlled crossover studies using the Trail Making Test (TMT, Parts A and B). In the two studies, healthy males took ASI for 14 and 3 days, respectively. In the first study, after 14 days of dosing, TMT B time decreased significantly from baseline (28% improvement, p = 0.045). In the second study, TMT B time decreased significantly compared to placebo (33% improvement, p = 0.024) in a 10-minute period. After 3 days of dosing, TMT B time significantly decreased from baseline scores (35% improvement, p < 0.001). These findings showed that ASI significantly improved the ability to perform complex cognitive tests requiring mental flexibility, processing speed, and executive functioning.

The double-blind, placebo-controlled, crossover study included adult men aged 18–35. In the first trial, 11 men with a history of moderate exercise routines were randomized to consume either a placebo or 1500 mg of Nitrosigine per day for 14 days, with a seven-day washout period separating the administrations. The second trial included 16 men with limited exercise routines who were randomized to consume either 1500 mg/day of Nitrosigine or a placebo for 3 days.

Post-exercise cognition (Journalof Exercise and Nutrition, 2020): Athletic performance depends on simultaneously handling physiological and cognitive demands. The objective of the study was to determine the efficacy of ASI (Nitrosigine®) to improve cognitive performance following intense exercise. Twenty-four healthy, recreationally active males (26.50 ± 4.85 years) were enrolled in a randomized, double-blind, placebo-controlled crossover study. A single oral dose of 1500 mg ASI or placebo was administered 30 minutes before a maximally graded exercise test. Prior to and following exercise, cognitive function was assessed via the Trail Making Test (TMT). Following intense exercise, ASI reduced the time to complete TMT Parts A and B (2.80 ± 5.97 and 5.54 ± 3.77 seconds, respectively) compared to increased time with placebo (19.82 ± 4.58 and 7.68 ± 5.06 seconds, respectively).

Multi-domain cognitive assessment (Gillis et al., 2021): ASI is an ergogenic aid that upregulates nitric oxide. Acute ASI supplementation has been shown to improve working memory and processing speed in young adults, but there was a lack of data examining other cognitive tasks. The purpose of the 2021 study was to examine acute ASI effects on young healthy adults by assessing multiple cognitive domains. Nineteen young adults (20.9 ± 3.2 years) completed a randomized, double-blind, crossover study consuming ASI (1.5 g ASI + 12 g dextrose) and a placebo (12 g dextrose). Participants completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and two digital cognitive assessments before consuming the supplement, and then completed the same battery of tests 60 minutes post-supplementation. Repeated measures ANOVA demonstrated that ASI consumption significantly improved total RBANS and immediate memory scores compared to the placebo (p < 0.05).

5.4 Esports and Gamer Cognition

Distinct from the exercise-focused studies, a line of research has examined ASI combined with extra inositol (nooLVL®) specifically in esports (video game) populations.

Sowinski et al. (2021) — Texas A&M University: Inositol-stabilized arginine silicate (ASI) ingestion has been reported to increase nitric oxide levels, while inositol (I) has been reported to enhance neurotransmission. The study examined whether acute ASI + I (inositol-enhanced bonded arginine silicate; nooLVL®) ingestion affects cognitive function in e-sport gamers. In a double-blind, randomized, placebo-controlled, crossover trial, 26 healthy male (n = 18) and female (n = 8) experienced gamers (23 ± 5 years, 171 ± 11 cm, 71.1 ± 14 kg, 20.7 ± 3.5 kg/m²) were randomly assigned to consume 1600 mg of ASI + I (nooLVL®, Nutrition 21) or 1600 mg of a maltodextrin placebo.

The authors concluded: "Results support contentions that ingesting nutrients like ASI + I that increase blood arginine and nitric oxide may enhance cognitive function and memory, possibly by improving blood flow and oxygen availability and/or enhancing neurotransmission. However, more research is needed to determine mechanisms of action." They also noted that additional research should further examine the effects of acute and chronic ASI + I ingestion on cognitive function, executive function, and memory in gamers.

A separate esports study (7-day intervention): The volunteers ingested 1600 mg of nooLVL® (600 mg of arginine, 105 mg of silicon, 385 mg inositol, and 60 mg potassium) per day for seven days and were subjected to a battery of computerized cognitive tests at baseline, on day 1, and again 7 days after ingesting the supplement. These investigators detected statistically significant differences in the Stroop test (attention/concentration) when comparing baseline versus day 1 (p = 0.0019), baseline versus day 7 (p = 0.0005), and day 1 compared to day 7 (p = 0.0369). Significance was also observed in the Mental Rotations test (visual representation) when contrasting baseline to day 1 (p = 0.0506) and baseline to day 7 (p = 0.0192).

Tartar et al. (2019): A prospective study evaluated the effects of a nutritional supplement intervention on cognition, mood states, and mental performance in video gamers. This study by Tartar, Kalman, and Hewlings was published in Nutrients (2019, 11(10):2326).

Evidence assessment: The studies trialling arginine-bonded inositol demonstrated limited results in the esports domain according to one scoping review. While several individual studies report statistically significant improvements on specific cognitive tests, the effect sizes are modest, sample sizes are small, intervention periods are short (acute to 7 days), and multiple studies have been funded by the ingredient manufacturer. The broader cognitive-enhancement literature on NO-boosting compounds remains preliminary.

5.5 Bone, Joint, and Connective Tissue Health

The arginine silicate inositol complex promotes bone and cartilage formation in mammals. Bioavailable nutritional silicon in the form of the arginine silicate inositol complex also increases bone density and prevents bone demineralization. In one preferred embodiment, the complex is administered prophylactically to prevent bone demineralization and cartilage degradation. These claims originate from patent literature and animal/preclinical work rather than human randomized controlled trials.

The effects of arginine and silicon on joint health and connective tissue metabolism in mammals are well documented, and the ASI complex has been shown to benefit bone and vascular health. Related benefits of the ASI complex include a report of decreased periodontal destruction in rats with induced periodontitis and decreased wound healing time in rats when ASI was applied topically. These are preclinical (animal) findings; no confirmatory human RCTs on bone outcomes with ASI have been published in the peer-reviewed literature retrieved in this review.

5.6 Hair Growth (Topical Application)

A U.S. patent (US 11,850,219) describes topical formulations of ASI for hair growth and thickening. In some embodiments, the formulation contains about 6.0% arginine silicate (w/w). No peer-reviewed human clinical data on topical hair growth applications were identified in the sources retrieved.

6. Body Systems and Health Areas Associated with ASI

• Cardiovascular and vascular endothelium: Although best known for its role in vasodilation leading to increased blood flow and cardiovascular health, NO has been shown to be involved in many physiological processes and to affect several organ systems.
• Skeletal muscle: ASI has been evaluated for its effects on exercise-induced muscle damage, blood flow to muscle, and recovery biomarkers (CK, LDH, myoglobin).
• Central nervous system / cognition: Enhanced NO availability induces vasodilation, increases blood flow to the working musculature, improves cardiovascular health, lowers blood pressure, improves exercise performance, and enhances memory. Research demonstrates that NO may be a prospective therapeutic approach in managing and mitigating mild cognitive impairment due to its mechanistic action, increasing systemic blood flow and, conceivably, cerebral circulation.
• Bone and connective tissue: Preclinical data and patent claims support potential benefits, but human RCT evidence is absent.
• Skin: Animal studies have explored the complex's effects on wound healing and UV-induced skin damage protection (combined with magnesium biotinate), as referenced in the literature.

7. Dosage Forms and Dosages Reported in Studies

The following dosages are reported only as documented in sourced studies:

• 1,500 mg/day of ASI (Nitrosigine®) for 4 days, in a DBPC-X study for workout performance and muscle recovery, administered as a beverage.
• 1,500 mg/day for 14 days, used in the first of two cognitive function trials (Trail Making Test study) in 11 healthy males.
• 1,500 mg/day for 3 days, used in the second cognitive function trial in 16 healthy males.
• 1,500 mg, single dose, administered 30 minutes before a maximally graded exercise test in the post-exercise cognition study.
• 1.5 g (1,500 mg) of ASI + 12 g dextrose, single acute dose, in the multi-domain cognitive RBANS study in 19 young adults.
• 1,600 mg of ASI + I (nooLVL®) — a single acute dose — in the esports gamer crossover trial (26 participants).
• 1,600 mg/day of nooLVL® (containing 600 mg arginine, 105 mg silicon, 385 mg inositol, 60 mg potassium) for 7 days in a separate esports intervention.
• 1,500 mg/day (three × 500 mg capsules) for 14 days in the pharmacokinetic characterization study in 10 healthy males.
• 1.5 g (1,500 mg) of Nitrosigine in the FMD vasodilation comparison study versus 8 g citrulline malate and 8 g dextrose placebo.

Across the published clinical literature, the predominant dose for Nitrosigine® is 1,500 mg per day, and for nooLVL® is 1,500–1,600 mg per day. Intervention durations have ranged from a single acute dose to 14 days; no long-term safety studies (months to years) were identified in the sources retrieved.

8. Safety Considerations

8.1 Regulatory Safety Determination

ASI has been affirmed as generally recognized as safe and is marketed in the United States after Food and Drug Administration New Dietary Ingredient Notification under the trade name Nitrosigine.

8.2 In-Study Safety Observations

Within the specific protocol of the pharmacokinetic study (14-day oral administration at 1,500 mg/day in 10 healthy males), the product was found to be safe. No safety concerns were raised by the muscle damage/recovery study.

8.3 Genotoxicity

A preclinical safety assay found that the arginine silicate inositol complex is not toxic in the mouse micronucleus assay (Komorowski JR, Juturu V, Gudi R; FASEB J. 2004;18:A869).

8.4 Cardiovascular — Heart Rate and Blood Pressure

Overall, clinical and preclinical data suggest that ASI (Nitrosigine®) can be safely used as a non-stimulant ingredient to increase physical energy and cognitive function without adverse cardiovascular effects. The effects of ASI intake on heart rate and blood pressure had not been formally evaluated until 2018. Other energy-stimulating ingredients, such as caffeine, bitter orange, and guarana, have been shown to increase heart rate, blood pressure, insomnia, nervousness, and restlessness. The 2018 Experimental Biology presentation (Sylla, Ojalvo, Komorowski) assessed these parameters and concluded that ASI does not produce adverse cardiovascular stimulant effects.

8.5 Limitations on Long-Term Safety Data

All identified human clinical studies of ASI were short-duration (acute single-dose to 14 days) and conducted in relatively small, healthy adult male populations. No long-term (multi-month or multi-year) human safety data are available in the peer-reviewed literature retrieved for this review. The predominant safety characterization therefore applies only to short-term oral use at the 1,500 mg/day dose level.

8.6 Potential Interactions

Because ASI functions partly by elevating nitric oxide and inducing vasodilation, there is a pharmacological basis for caution regarding co-administration with other vasodilatory agents or NO-augmenting substances (such as phosphodiesterase-5 inhibitors). Supplementation of L-arginine has been shown to benefit hypertensive patients by correcting abnormal vasodilation. A meta-analysis of randomized, double-blind, placebo-controlled trials showed that oral L-arginine significantly lowered systolic and diastolic blood pressure compared with placebo. No specific drug interaction studies for ASI are documented in the peer-reviewed literature retrieved in this review.

8.7 Funding Conflicts in the Evidence Base

A noteworthy limitation across much of the clinical evidence on ASI is that many studies are funded by or conducted in collaboration with Nutrition 21, LLC — the commercial developer and patent holder of Nitrosigine® and nooLVL®. This does not invalidate the findings, but it is a relevant consideration when evaluating the strength and independence of the evidence base.

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