L-theanine and caffeine: what they are and where you find them
PäivitettyL-theanine is an amino acid found naturally in tea leaves; caffeine is found in coffee, tea, cola and energy drinks. A cup of tea contains both, while coffee contains caffeine but no L-theanine. Optimal Native pouches contain L-theanine together with caffeine in Morning Energy and Daily Flow, and L-theanine without caffeine in Evening Relax.
Key points
• L-theanine is an amino acid from the tea plant.
• A 314 ml cup of black tea contained about 25 mg of L-theanine in one study.
• Optimal Native: 50 mg L-theanine in Morning Energy and Daily Flow, 100 mg in Evening Relax.
• Caffeine from all sources counts towards the same daily total: up to 400 mg a day for adults.
Table of contents
- What is L-theanine?
- What is caffeine?
- L-theanine and caffeine in tea
- L-theanine and caffeine in Optimal Native pouches
- FAQ
What is L-theanine?
L-theanine is an amino acid. It occurs naturally in the leaves of the tea plant (Camellia sinensis), which is used for black, green and white tea.
In food supplements, L-theanine is usually added as a purified ingredient.
What is caffeine?
Caffeine is a natural substance found in coffee beans, tea leaves and cocoa. It is also added to cola, energy drinks and some food supplements. The UK food safety agencies say up to 400 mg of caffeine a day is unlikely to cause adverse effects in adults, with a limit of 200 mg a day for pregnant women (Food Standards Scotland and the FSA, 2024). See How much caffeine is too much?
L-theanine and caffeine in tea
A cup of tea gives you both. In a study published in the Journal of Functional Foods (van der Pijl et al., 2010), a 314 ml cup of black tea made with a 2 g tea bag contained about 25 mg of L-theanine. A 250 ml cup of black tea contains about 55 mg of caffeine (EUFIC). The amounts vary with the type of tea and how it is brewed: in a 2025 study, black and green teas had the most L-theanine of the teas tested, and longer brewing increased both L-theanine and caffeine (Ayakdaş and Ağagündüz, Foods, 2025).
Coffee contains caffeine (about 90 mg in a 200 ml cup) but no L-theanine. More on this: Caffeine in coffee vs tea vs green tea.
L-theanine and caffeine in Optimal Native pouches
| Per pouch | Caffeine | L-theanine |
|---|---|---|
| Morning Energy | 200 mg | 50 mg |
| Daily Flow | 75 mg | 50 mg |
| Evening Relax | 0 mg | 100 mg |
Work out your own total: caffeine calculator.
Morning Energy and Daily Flow also contain NR (nicotinamide riboside, a precursor of NAD+) and vitamins B6 and B12; Daily Flow also contains choline. Vitamins B6 and B12 contribute to normal energy-yielding metabolism, normal psychological function and the reduction of tiredness and fatigue. Evening Relax also contains GABA, chamomile extract, lemon balm extract and magnesium.
One pouch at a time. Do not exceed the stated recommended daily dose. Morning Energy contains 200 mg and Daily Flow 75 mg of caffeine per pouch. Not recommended for children or pregnant or breast-feeding women. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Keep out of reach of young children.
FAQ
Is L-theanine the same as caffeine?
No. L-theanine is an amino acid; caffeine is a different natural substance. Tea contains both.
Does coffee contain L-theanine?
No. L-theanine comes from the tea plant.
How much L-theanine is in a cup of tea?
In one study, about 25 mg in a 314 ml cup of black tea. It varies with the tea and brewing.
Is there L-theanine in Evening Relax?
Yes, 100 mg per pouch, and no caffeine.
Read more: Caffeine pouches in the UK
Optimal Native is coming to the UK. One stack for the whole day: Morning Energy, Daily Flow and Evening Relax. Pre-orders ship from 15 December 2026.