L-Theanine for Parasympathetic Activation
L-theanine produces measurable acute calming and small HRV improvements during stress, without sedation.
Overview
Verdict
How It Works
Dosing & Protocol
Typical dose
- Recommended dose
- 200mg as needed
- Expected timeframe
- Within 60 minutes
Protocol
- form
- L-theanine capsules
- duration
- Acute; effects within an hour
- co factor
- Take with or without food. Evidence is mixed. Several small randomised studies show that 200 mg of theanine attenuates the heart rate and salivary immunoglobulin A responses to an acute stress task, and reduces salivary cortisol - findings consistent with dampened sympathetic activation and, by implication, relatively greater parasympathetic tone. A few studies have looked at heart rate variability, the standard measure of parasympathetic activity, with inconsistent results. So the direction is plausible and the stress-response data are reasonably consistent, but the specific claim that theanine activates the parasympathetic nervous system rests on indirect markers, and no trial has established a reliable HRV effect.
- titration
- Up to 400 mg per dose
- starting dose
- 200 mg per dose
Evidence
What the studies say
The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review
Williams JL, Everett JM, D'Cunha NM +7 more
L-theanine at 200-400 mg/day reduced stress and anxiety in people exposed to stressful conditions.
L-theanine and acute stress and anxiety responses: a systematic review of randomized controlled trials
Williams JL, Everett JM, D'Cunha NM +3 more
L-theanine reduced acute stress and anxiety in stress-inducing settings
Safety
Caveats
Acute tool only. Slow-paced breathing outperforms it and costs nothing.
Less likely to help if
Medical Disclaimer
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Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.