Comparison
EGCG vs L-Theanine
Side-by-side of EGCG and L-Theanine. 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.
EGCG
EGCG supplement guide: 300-600 mg/day green tea catechin for fat loss and cardiovascular markers. Hepatotoxicity risk above 800 mg/day fasted.
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.
Effects at a glance
EGCG
- •Modest fat loss (~1.3 kg over 12 weeks) when combined with caffeine and caloric deficit
- •Small reductions in LDL cholesterol (3-6 mg/dL) and systolic blood pressure (2-3 mmHg)
- •EFSA flags hepatotoxicity risk above 800 mg/day, particularly when taken fasted
- •Bioavailability is 0.1-1.0%; gut microbiome variation drives population-variable response
- •Green tea extract typically combines EGCG with caffeine and L-theanine for additive effects
- •Reduces non-heme iron absorption when co-administered with meals
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
Side-by-side
| Attribute | EGCG | L-Theanine |
|---|---|---|
| Category | natural | supplement |
| Also known as | epigallocatechin gallate, green tea extract | theanine, gamma-glutamylethylamide |
| Half-life (hr) ↗ | 3 | 1.5 |
| Typical dose (mg) ↗ | 400 | 200 |
| Dosing frequency | 1 to 2 times daily with food | as needed (with caffeine) or daily |
| Routes | oral | oral |
| Onset (hr) | 1.5 | 0.5 |
| Peak (hr) | 2 | 1 |
| Molecular weight | 458.37 | 174.2 |
| Molecular formula | C22H18O11 | C7H14N2O3 |
| Mechanism | Inhibits catechol-O-methyltransferase (COMT) to prolong norepinephrine signaling; activates AMPK; scavenges reactive oxygen species via gallate ester; modulates gut microbiome and pancreatic lipase activity. | Crosses BBB; modulates GABA/dopamine/serotonin (modest); increases alpha-wave EEG activity; dampens stress-induced sympathetic response without sedation. |
| Legal status | Dietary supplement; warning labels required above 800 mg/day in some EU jurisdictions | OTC dietary supplement |
| WADA status | allowed | allowed |
| DEA / Rx | Not scheduled | OTC supplement |
| Pregnancy | Avoid high-dose extracts; moderate green tea consumption appears acceptable | Insufficient supplement-dose data; tea-source intake safe |
| CAS | 989-51-5 | 3081-61-6 |
| PubChem CID | 65064 | 439378 |
| Wikidata | Q307091 | Q909931 |
Safety profile
EGCG
Common side effects
- nausea
- abdominal discomfort
- diarrhea
- jitteriness (with caffeine)
- sleep disruption (with caffeine)
Contraindications
- pregnancy at high-dose extracts
- active liver disease
- iron deficiency anemia (separate dosing)
Interactions
- iron supplements: reduces non-heme iron absorption; separate by 2 to 3 hours(moderate)
- anticoagulants: additive effects at high catechin doses(minor)
- beta-blockers (nadolol): reduced absorption when taken simultaneously(moderate)
- hepatotoxic supplements (high-dose niacin, kava): theoretical additive hepatotoxicity at high EGCG doses(moderate)
- stimulants and caffeine: additive thermogenic and cardiovascular effects(minor)
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)
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. EGCG is the right call when one of the conditionals below applies.
- → If your priority is metabolic health and glucose control, pick EGCG.
- → If your priority is healthspan extension, pick EGCG.
- → If your priority is focus or working memory, pick L-Theanine.
- → If your priority is stress and HPA-axis regulation, pick L-Theanine.
Default choice: L-Theanine. Lower friction to source, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for EGCG 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 EGCG and L-Theanine?
EGCG and L-Theanine differ in category (natural vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, EGCG or L-Theanine?
EGCG half-life is 3 hours; L-Theanine half-life is 1.5 hours.
Can you stack EGCG with L-Theanine?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
Go deeper