Looking to enhance muscle pumps, accelerate exercise recovery, and eliminate exercise-induced fatigue? NOW Foods Arginine & Ornithine brings together two biologically synergistic amino acids in a clinically recognized 2:1 ratio (1,000 mg L-Arginine to 500 mg L-Ornithine per 2-capsule serving). Together, these free-form amino acids support the body’s natural nitric oxide (NO) production, promote healthy urea cycle waste detox, and encourage restorative tissue repair.
Independent Retailer Trust Note: Delivered directly to you by VitaNet®, LLC — a family-owned, independent nutritional retailer serving customers online since 1995 from Hartville, Ohio[cite: 1]. Backed by over 31 years of supplement expertise and an unconditional 100% money-back guarantee that covers return shipping[cite: 1].
✓ Dual Action CycleDrives vascular blood flow while clearing excess ammonia produced during high-intensity training.
✓ ISO 17025 CertifiedIn-house tested for heavy metals, microbials, and purity down to parts-per-billion constraints.
How Arginine and Ornithine Work Together (In Plain English)
Many athletes take L-Arginine by itself, but human biochemistry shows that combining it with L-Ornithine yields superior results. Think of these two amino acids as a cooperative relay team that keeps your cardiovascular and cellular cleansing systems running smoothly:
1. The Nitric Oxide Highway (Muscle Fullness & Blood Flow)
L-Arginine acts as the primary raw building block for nitric oxide (NO). Nitric oxide signals the smooth inner muscles of your blood vessels to relax and expand — a physical process called vasodilation. By opening up these pathways, more oxygen, glucose, and nutrient-dense blood can reach active muscle tissue during workouts, supporting fullness, endurance, and pumps.
2. The Ammonia Scrub (The Urea Cycle & Fatigue Delay)
When you lift heavy weights or run sprints, your body breaks down proteins and amino acids for immediate energy. A natural byproduct of this breakdown is ammonia — a toxic waste chemical that causes burning sensations, muscular weakness, and brain fog. The liver safely disposes of ammonia through an internal filtration system known as the urea cycle. L-Ornithine serves as the central spark plug for this cycle. Supplementing with ornithine speeds up ammonia clearance, converting cellular waste into water-soluble urea that your kidneys can safely filter out.
3. The “Arginine-Sparing” Synergy
When you take L-Arginine alone, your liver enzymes (specifically arginase) quickly break a large portion of it down into ornithine before it ever reaches your vascular system. By supplying pre-formed L-Ornithine directly alongside L-Arginine, you satisfy the liver’s metabolic demand, allowing more free-form L-Arginine to circulate through your bloodstream to fuel nitric oxide synthesis and tissue recovery.
What the Clinical Research Says (Evidence-Based Insights)
Rather than relying on marketing claims, let’s look directly at peer-reviewed sports science and human trials evaluating the combination of L-Arginine and L-Ornithine:
Growth Hormone (GH) and IGF-1 Secretion in Strength Athletes
In a randomized double-blind trial published in the Journal of Strength and Conditioning Research (Zajac et al., 2010), strength-trained athletes were administered arginine and ornithine or a placebo prior to heavy resistance exercise. Athletes receiving the amino acid combination demonstrated statistically significant elevations in both serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels compared to the placebo group. The researchers concluded that arginine and ornithine act synergistically to influence endocrine responses after resistance exercise.
Reference: Zajac A, et al. J Strength Cond Res. 2010 Apr;24(4):1082-90. PMID: 20300016.
Strength Output, Lean Body Mass, and Collagen Remodeling
A classic clinical trial published in the Journal of Sports Medicine and Physical Fitness (Elam et al., 1989) examined male subjects engaged in high-intensity progressive weight training over 5 weeks. Subjects receiving daily L-arginine and L-ornithine experienced significantly higher gains in total lean body mass and maximum strength along with lower urinary hydroxyproline (a biological marker indicating reduced muscle and connective tissue breakdown) compared to control subjects.
Reference: Elam RP, et al. J Sports Med Phys Fitness. 1989 Mar;29(1):52-6. PMID: 2770273.
Reduction of Physical Fatigue & Enhanced Urea Synthesis
A clinical study published in Nutrition Research (Sugino et al., 2008) tested ornithine supplementation during endurance physical activity. The study demonstrated that supplementing ornithine promoted lipid metabolism, suppressed exercise-induced accumulation of blood ammonia, and meaningfully reduced subjective feelings of physical exhaustion.
NOW Foods Laboratory Testing & Contaminant Verification
In dietary supplements, safety and label accuracy are just as vital as biological efficacy. Because raw amino acids are produced via commercial microbial fermentation, poor manufacturing oversight can leave behind dangerous residues, unreacted solvents, bacterial toxins, or heavy metal contamination. NOW Foods operates one of the most advanced analytical testing systems in the world to ensure every batch is clean, pure, and safe.
NOW Foods maintains full ISO/IEC 17025 accreditation (audited by the American Association for Laboratory Accreditation – A2LA) for its state-of-the-art analytical testing facilities. Their team of in-house chemists, toxicologists, and microbiologists conducts over 19,000 individual analytical tests each month across incoming raw ingredients and finished goods.
ICP-MS Heavy Metal Testing (Parts-Per-Billion Precision)
Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), NOW screens every incoming amino acid lot for trace heavy metals — including Lead, Cadmium, Arsenic, and Mercury. While federal FDA Current Good Manufacturing Practices (cGMP 21 CFR Part 111) outline baseline standards, NOW voluntarily enforces limits that satisfy California Proposition 65 — the strictest environmental and chemical toxicity standard in the United States.
HPLC & FTIR Molecular Identity Verification
To guard against counterfeit or degraded raw materials, NOW utilizes High-Performance Liquid Chromatography (HPLC) to verify exact molecular potency and Fourier Transform Infrared Spectroscopy (FTIR) to verify the unique optical fingerprint of both L-Arginine and L-Ornithine hydrochloride before blending.
Comprehensive Microbial & Adulterant Screening
Finished capsules undergo biological pathogen screening to guarantee zero contamination with Salmonella spp., Escherichia coli, Staphylococcus aureus, total yeast, and molds. The facility is independently audited and certified by UL Solutions and holds an NPA A-Rated Good Manufacturing Practice (GMP) certification.
Supplement Facts & Complete Ingredient Profile
Every 2-capsule serving provides 1,000 mg of pure, free-form L-Arginine and 500 mg of bioavailable L-Ornithine. Below is the verified label breakdown for NOW item #0042 (VitaNet product N0042):
Hypromellose (cellulose capsule) and Stearic Acid (vegetable source).
Allergen & Manufacturing Information:
Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut, or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.
Crucial Safety Guidelines, Contraindications & Who Should NOT Take This
In accordance with strict healthcare guidance, dietary supplements that influence nitric oxide pathways and nitrogen metabolism require careful safety consideration. Please read these clinical contraindications before purchasing:
1. Prior Heart Attack or Coronary Artery Disease (Absolute Warning)
Do not use if you have a history of myocardial infarction (heart attack) or established coronary artery disease. A landmark randomized clinical study published in JAMA (the VINTAGE MI trial, Schulman et al., 2006) showed that high-dose oral L-arginine supplementation after an acute heart attack did not improve vascular stiffness and may increase health risks in post-infarction patients.
Herpes simplex viruses require cellular L-Arginine to synthesize viral proteins and replicate. If you are prone to cold sores or genital herpes flare-ups, supplemental arginine may trigger viral activation. If you choose to supplement arginine, many nutrition specialists advise balancing it with L-Lysine, which competes with arginine for cellular uptake and helps keep the virus dormant.
Because L-arginine converts to nitric oxide and widens blood vessels, taking it alongside antihypertensive drugs (such as ACE inhibitors, beta blockers, or ARBs) or PDE-5 inhibitors (such as sildenafil or tadalafil) can cause blood pressure to drop unexpectedly low (hypotension). Always consult your cardiologist or physician before combining them.
4. Glaucoma, Renal Impairment, Pregnancy, or Upcoming Surgery
Individuals with glaucoma, active kidney or liver disease, pregnant or nursing women, and those scheduled for surgery within 14 days should refrain from using supplemental arginine without direct medical oversight.
How to Take for Maximum Absorption and Results
To experience the full vascular and recovery benefits of free-form amino acids, proper timing is essential. Follow these simple guidelines:
Option A: Pre-Workout (For Blood Flow & Pumps)
Take 2 capsules approximately 30 to 45 minutes prior to training with 8 to 12 ounces of water or fruit juice. Taking it with simple carbohydrates can assist cellular amino acid uptake via mild insulin stimulation.
Take 2 capsules right before sleep on an empty stomach. The human body experiences its largest natural pulse of growth hormone during slow-wave deep sleep. Arginine and ornithine taken at night support this restorative cycle.
✓ The Golden Rule: Always Take on an Empty Stomach
Free-form amino acids rely on specific intestinal transporters (known as the basic amino acid transport system, or y+ system). If you take these capsules with a heavy whey protein shake, steak, or whole eggs, the massive influx of dietary amino acids will crowd the intestinal transporters, substantially reducing the amount of arginine and ornithine absorbed into your bloodstream. Take at least 45 minutes before meals or 2 hours after a meal.
Frequently Asked Questions (FAQ)
Why are Arginine and Ornithine combined in a 2:1 ratio?
The 2:1 ratio provides 1,000 mg of L-Arginine and 500 mg of L-Ornithine. This balance reflects human urea cycle kinetics: L-arginine fuels nitric oxide and protein synthesis, while L-ornithine recycles in the liver to remove metabolic ammonia. Supplying both amino acids together reduces the rapid enzymatic degradation of arginine in the digestive tract, allowing more arginine to enter peripheral circulation.
What does “Free-Form” amino acid mean?
Free-form means the amino acids are individual, unbound molecules that do not require digestive enzymes or stomach acid to cleave peptide bonds. They pass rapidly through the stomach into the small intestine for fast assimilation into your bloodstream, making them ideal for targeted workout or bedtime supplementation.
How does NOW Foods ensure their amino acids are free from heavy metals?
NOW Foods tests every batch in their ISO/IEC 17025 accredited in-house laboratories using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This instrument detects heavy metals such as lead, cadmium, mercury, and arsenic down to trace parts per billion (ppb), adhering to contaminant limits that meet or exceed stringent California Proposition 65 thresholds.
Why shouldn’t I take this supplement with my protein shake?
Dietary protein shakes contain dozens of competing amino acids that utilize the same cationic transport channels in your gut. If taken simultaneously, the absorption of free-form arginine and ornithine is drastically reduced. For maximum effectiveness, take this product on an empty stomach with water or fruit juice.
Can people prone to cold sores take Arginine and Ornithine?
Those with frequent herpes simplex outbreaks (cold sores) should exercise caution. Arginine is utilized by the herpes virus to replicate. If you do use this supplement and notice tingling or flare-ups, consider pairing it with supplemental L-Lysine or reducing your dose, and always talk to your physician.
What is the difference between SKU 0040 and SKU 0042?
The formulation and potency are identical (500 mg Arginine / 250 mg Ornithine per capsule). SKU 0040 is the 100-capsule bottle (a 50-day supply), whereas SKU 0042 (N0042 on VitaNet) is the larger 250-capsule value bottle offering a full 125-day supply.
What is VitaNet’s return policy on this product?
VitaNet®, LLC stands behind every purchase with an unconditional 100% money-back guarantee[cite: 1]. If you are not completely satisfied with NOW Arginine & Ornithine, VitaNet will refund your order and even pay the return shipping cost, even on opened bottles[cite: 1].
Scientific References & Authoritative Citations
Zajac A, Poprzecki S, Zebrowska A, Chalimoniuk M, Langfort J. (2010). Arginine and ornithine supplementation increases growth hormone and insulin-like growth factor-1 serum levels after heavy-resistance exercise in strength-trained athletes. Journal of Strength and Conditioning Research, 24(4):1082-90. PMID: 20300016.
Elam RP, Hardin DH, Sutton RA, Hagen L. (1989). Effects of arginine and ornithine on strength, lean body mass and urinary hydroxyproline in adult males. Journal of Sports Medicine and Physical Fitness, 29(1):52-56. PMID: 2770273.
Sugino T, Shirai T, Kajimoto Y, Kajimoto O. (2008). L-Ornithine supplementation attenuates physical fatigue in healthy volunteers by promoting lipid metabolism and activating the urea cycle. Nutrition Research, 28(11):738-743. PMID: 19083482.
Schulman SP, Becker LC, Kass DA, et al. (2006). L-arginine therapy in acute myocardial infarction: the Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial. JAMA, 295(1):58-64. PMID: 16391217.
Cynober L. (2002). Pharmacokinetics of arginine and ornithine. The Journal of Nutrition, 132(4 Suppl):737S-740S. PMID: 11925471.
Morris SM Jr. (2004). Enzymes of arginine metabolism. The Journal of Nutrition, 134(10 Suppl):2743S-2747S. PMID: 15465778.
