AMINO ACIDS
L-theanine
L-theanine, an amino acid from tea leaves, supports calm focus and relaxation without drowsiness.
Also known as: theanine, green tea amino acid, L theanine
At a glance
- Category
- Amino Acids
- In an apiece formula
- 200 mg a day (you can change it)
- Recommended intake
- No recommended intake (not an essential nutrient)
- Upper limit
- No established UL
- Studied for
- Stress & resilience, Focus & memory, Relaxation*
- Reference
- NIH ODS: Dietary Supplements, What You Need to Know
What the research says
In healthy adults, 200 mg of L-theanine a day for 4 weeks lowered stress scores and improved sleep quality.*
RCT (double-blind, placebo-controlled crossover) · 30 · Hidese S, Nutrients 2019. Read the study on PubMed
Who should be careful
Our safety rules leave L-theanine out of a formula, or keep the amount lower, with:
Life stage
- Pregnancy
- Breastfeeding
- Trying to conceive
Always check with your doctor or pharmacist before adding a supplement if you take medication, are pregnant or nursing, or have a health condition. Stay under the upper limit from all sources combined, including multivitamins.
Symptoms it’s studied for
- Tired or low energy
- Afternoon crash
- Brain fog or poor focus
- Poor sleep
- Anxious or stressed
- Bloating or gas
- Catching every cold
- Hair shedding
- Skin issues (acne, dry, eczema)
- PMS or cycle symptoms
- Low libido
- Sugar cravings
From the Journal
- Why am I always tired, and what causes the afternoon crash?
The everyday reasons for constant tiredness and the 3 pm slump, which blood tests to ask your doctor about, which nutrients have been studied, and the signs that need a doctor soon.
- Which supplements help you sleep? What the research shows
Magnesium, L-theanine, melatonin, saffron, glycine and tart cherry: what the trials found, the doses studied, and when poor sleep is a reason to see a doctor instead.
Questions
How much L-theanine a day?
apiece formulas usually include 200 mg a day. The recommended intake for adults is No recommended intake (not an essential nutrient). Upper limit: No established UL.
What is L-theanine used for?
L-theanine, an amino acid from tea leaves, supports calm focus and relaxation without drowsiness. In apiece it is part of formulas for Stress & resilience, Focus & memory, Relaxation.*
Who should be careful with L-theanine?
apiece’s safety rules leave it out or limit it with: Pregnancy; Breastfeeding; Trying to conceive. Check with your doctor or pharmacist if any apply to you.
Can I get L-theanine in a personalized supplement?
Yes. apiece builds one daily blend around your goals and, if you have them, your lab results. L-theanine can be part of it at the amount listed, with every ingredient shown and never more than 10 capsules a day.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This page is general information, not medical advice. Check with your doctor or pharmacist before starting a supplement, especially if you take medication, are pregnant or nursing, or have a health condition. Updated 2026-10-21.