Comparison
L-Theanine vs Spermidine
Side-by-side of L-Theanine and Spermidine. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
L-Theanine
L-theanine is a non-protein amino acid found in tea leaves. The most-replicated nootropic; pairs with caffeine at 1:1 (100-200 mg each) for acute focus.
Spermidine
Spermidine supplement benefits cover autophagy induction, longevity signals, and cognition. Wheat germ extract data, doses, and human trials reviewed.
Effects at a glance
L-Theanine
- •Non-protein amino acid in tea; the most-replicated nootropic in the human RCT literature
- •Caffeine + theanine at 1:1 (100-200 mg each) is the gold-standard acute focus stack
- •Solo doses of 200-400 mg reduce subjective stress and improve sleep quality
- •Increases alpha-wave EEG activity within 30-45 minutes of 200 mg oral dose
- •Crosses blood-brain barrier; bioavailability high, half-life 60-90 minutes
- •Clean safety record; minimal interactions at supplement doses
Spermidine
- •Endogenous polyamine that induces autophagy via EP300 acetyltransferase inhibition and TFEB activation
- •Concentrated in wheat germ, soybeans, aged cheese, and mushrooms; ~10 to 15 mg/day in Mediterranean diets
- •Eisenberg 2016 reported dietary spermidine extended mouse lifespan and improved cardiac function
- •Wirth 2018 pilot (n=28) reported cognitive signal at 0.9 mg/day in older adults at risk for dementia
- •Larger Wirth 2019 follow-up (n=85) did not replicate the memory benefit at 12 months
- •Generally regarded as safe at supplemental doses; food-source position is reassuring
Side-by-side
| Attribute | L-Theanine | Spermidine |
|---|---|---|
| Category | supplement | supplement |
| Also known as | theanine, gamma-glutamylethylamide | spermidine trihydrochloride, wheat-germ-extract spermidine |
| Half-life (hr) ↗ | 1.5 | 6 |
| Typical dose (mg) ↗ | 200 | 1.2 |
| Dosing frequency | as needed (with caffeine) or daily | daily, typically morning with food |
| Routes | oral | oral |
| Onset (hr) | 0.5 | 2 |
| Peak (hr) | 1 | 4 |
| Molecular weight | 174.2 | 145.25 |
| Molecular formula | C7H14N2O3 | C7H19N3 |
| Mechanism | Crosses BBB; modulates GABA/dopamine/serotonin (modest); increases alpha-wave EEG activity; dampens stress-induced sympathetic response without sedation. | Induces macroautophagy via inhibition of EP300 histone acetyltransferase and activation of TFEB-mediated lysosomal biogenesis. Substrate for hypusination of eIF5A, required for translation of mitochondrial respiration proteins. |
| Legal status | OTC dietary supplement | OTC dietary supplement (wheat-germ extract has GRAS status in US) |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement | OTC supplement (not scheduled) |
| Pregnancy | Insufficient supplement-dose data; tea-source intake safe | Insufficient data; not routinely recommended at supplemental doses |
| CAS | 3081-61-6 | 124-20-9 |
| PubChem CID | 439378 | 1102 |
| Wikidata | Q909931 | Q411089 |
Safety profile
L-Theanine
Common side effects
- mild GI upset (rare)
- headache (rare)
Contraindications
- pregnancy / lactation (insufficient data at supplement doses)
- concurrent strong GABAergics without caution
Interactions
- caffeine: synergistic for acute focus; dampens jitter without blunting alertness(minor)
- benzodiazepines / alcohol: potential additive sedation(minor)
Spermidine
Common side effects
- mild GI upset (rare)
- headache (rare)
Contraindications
- wheat-germ allergy or celiac disease (for wheat-germ-extract products)
- active cancer (theoretical)
- pregnancy and lactation (insufficient data)
Interactions
- DFMO (difluoromethylornithine): competing polyamine metabolism; do not combine without oncology guidance(moderate)
Which Should You Take?
L-Theanine comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-A outcome catalogued. Spermidine is the right call when one of the conditionals below applies.
- → If your priority is stress and HPA-axis regulation, pick L-Theanine.
- → If your priority is sleep onset or sleep quality, pick L-Theanine.
- → If your priority is healthspan extension, pick Spermidine.
Edge case: Half-lives differ materially (L-Theanine ~1.5 hr vs Spermidine ~6 hr). Spermidine reaches steady state faster; L-Theanine is easier to dial in if tolerability is uncertain.
Default choice: L-Theanine. Lower friction to source, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Spermidine only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between L-Theanine and Spermidine?
L-Theanine and Spermidine differ in category (supplement vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, L-Theanine or Spermidine?
L-Theanine half-life is 1.5 hours; Spermidine half-life is 6 hours.
Can you stack L-Theanine with Spermidine?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
Go deeper