Agmatine SulfateAmino Acid

• Neuropathic pain from lumbar disc radiculopathyPossibly helps

  This is the strongest human evidence agmatine has, and it is one trial. A randomized, double-blind, placebo-controlled trial of 2.670 g/day for 14 days reported 26.7% improvement in pain from baseline against 6.0% on placebo (p≤0.05) [1].
  
  SF-36 quality-of-life scores improved 70.8% versus 20.0% on placebo in the same trial [1].
  
  No treatment-related adverse events were noted [1]. One small trial is a promising start rather than a settled result, which is why this sits in the unclear column [1]. ^[1]

• Painful small fiber neuropathyPossibly helps

  An open-label case series in painful small fiber neuropathy, mostly diabetic, reported a 46.4% average reduction in pain intensity after 2 months at 2.67 g/day (p<0.00001) [2].
  
  Only 11 people completed it, and the authors are the ones flagging that it was open-label, uncontrolled and small [2].
  
  They call for larger randomized trials before anyone draws conclusions from it [2]. ^[2]

• Bodybuilding and nitric-oxide pump claimsPossibly helps

  ⚠ No human clinical trial of agmatine for exercise performance turned up in this research at all [1][2].
  
  The human trials that do exist measured neuropathic pain outcomes, not performance [1][2].
  
  The performance marketing rests on mechanism — agmatine's reported effects on nitric oxide synthase — rather than on a measured result in people [6]. ^[1]

• Depression and anxietyPossibly helps

  Animal studies in the sources reviewed report antidepressant-like and anxiolytic-like effects [4][6].
  
  No robust human trial for either turned up [4]. Rodent signals routinely fail to carry over, so this is a hypothesis rather than a finding [4]. ^[4]

• Neuroprotection after stroke or injuryPossibly helps

  Animal models of stroke and nerve injury report neuroprotective effects [6].
  
  Again, no human trial [4]. A biodistribution study did confirm that systemically delivered agmatine reaches brain and spinal cord tissue, which is a necessary first condition rather than evidence of benefit [5]. ^[6]

• Agmatine sulfateEffectively the only option with human data behind it.

  Elemental content

  The sulfate salt of agmatine, described in the primary literature as the commonly used salt form for both research and supplements [3][4]

  Absorption

  In rats, oral bioavailability was estimated at 29–35%, with an oral plasma half-life of 74–117 minutes against 15–19 minutes intravenously [5]

  Best for

  Effectively the only option with human data behind it. In humans the apparent blood half-life of ingested agmatine is about 2 hours, based on renal elimination of the unmetabolized compound [3][6].

• Agmatine free base⚠ Nothing that can be substantiated.

  Elemental content

  The unsalted molecule, sold on claims of better absorption

  Absorption

  No study directly comparing human bioavailability of the sulfate salt against the free base turned up in this research [5]

  Best for

  ⚠ Nothing that can be substantiated. Marketing that calls one salt form meaningfully more bioavailable than the other has no verifiable primary source behind it here [5].

• Diarrhea and nausea at the highest dose

  Across the open-label dose-escalation study, the only adverse events recorded at any dose were mild-to-moderate diarrhea and mild nausea [1].
  
  They appeared only in the 3.560 g/day cohort and resolved after dosing stopped [3].
  
  The randomized trial dose of 2.670 g/day for 14 days produced no treatment-related adverse events [1]. ^[1]

• Blood-pressure medication

  No human drug-interaction study for agmatine turned up in this research [3].
  
  In rats, chronic high-dose oral agmatine sulfate produced slight but statistically significant drops in blood pressure over 95 days, which returned to baseline within 20 days of stopping [3].
  
  A pharmacology summary describes mild reductions in heart rate and blood pressure through imidazoline receptors, norepinephrine release and nitric oxide [6].
  
  ⚠ Read an additive effect with blood-pressure medication as mechanistically plausible, not clinically established [3][6]. ^[3]

• No established upper limit

  ⚠ No formal RDA and no tolerable upper intake level exist for agmatine sulfate [1].
  
  Every dosing figure on this page comes from a handful of small trials, the largest randomized arm having 51 participants, rather than from population-level safety data [1]. ^[1]

Agmatine turns up at low levels across plant, animal and fish foods, and at markedly higher levels in fermented foods and alcoholic drinks [3][7].

The reason is the fermentation itself. Yeasts and bacteria produce agmatine, so it is largely not a native constituent of the raw food [7].

Among alcoholic drinks, sake averaged 114 mg/L, the highest surveyed [7].

Beer ran 0.5–42 mg/L with a mean around 12 mg/L, making agmatine the most abundant biogenic amine in beer [7].

Red wine ranged from not-detected to 22 mg/L; white wine from not-detected to 6.5 mg/L [7].

Fish is the other notable source. Fresh fish averaged 92 mg/kg, spanning not-detected to 401 mg/kg [7].

Agmatine has been proposed as a fish freshness indicator, since levels start low and climb during chilled storage, passing 300 mg/kg after 7 days in some species [7].

Meat carries far less. Fresh meat averaged 0.8 mg/kg, up to 3.1 mg/kg [7].

Fermented and ripened meat products averaged 6.2 mg/kg, reaching 43 mg/kg [7].

Korean doenjang, a fermented soybean paste, had the widest range of anything surveyed: not-detected to 5,508 mg/kg, mean 473 mg/kg [7].

The Japanese soy sauce and miso samples in the same survey showed little to none [7].

Dairy is essentially a non-source. Ripened cheese averaged 1.1 mg/kg and fresh cheese 0.1 mg/kg, while milk and kefir were not detected [7].

Roasted coffee can carry up to about 1.2 mg/kg, formed during high-temperature roasting. None was detected in green, unroasted beans [7].

No trial identified in this research tested timing directly [2].

The one protocol that specified a schedule split 2.67 g/day across the day, either 3 capsules twice daily or 2 capsules three times daily, with or after meals [2].

The radiculopathy trial used the same daily total, but the source read here did not say how it was divided [1].

⚠ Splitting doses is inferred from pharmacokinetics, not from a timing trial. Agmatine's apparent blood half-life in humans is about 2 hours, which would favour spreading the dose, but that has not been tested against once-daily [3][6].