Look at the label on a caffeine pouch and you may find an unfamiliar name below the caffeine: L-theanine.
Most people know what caffeine is. L-theanine is less familiar, even though it comes from the same plant.
This article covers what it is as an ingredient, where the name comes from, and how much is in Ne9. It does not describe what it does in the body.
What it is
L-theanine is an amino acid. It occurs naturally in the leaves of the tea plant (Camellia sinensis) — the same leaves that green tea, black tea and oolong tea are all made from.
Caffeine comes from those leaves too. The two are found together in the same plant, which is why they appear together on so many labels.
Where the name comes from
It was first isolated from gyokuro, a shaded Japanese green tea, in 1949. The name comes from Thea, the old botanical genus name for the tea plant.
The "L-" refers to the molecular form. Amino acids come in two mirror-image forms, and the L- form is the one that occurs in nature.
Its relationship to umami
L-theanine is one of the components associated with the umami and sweetness of green tea.
This is why shaded teas such as gyokuro and kabusecha, grown under cover before harvest, are described as having more umami. Shading changes the composition of the leaf.
It is a component of taste. That is a fact about the tea, not a claim about anything else.
Why "how many mg in a cup of tea" is hard to answer
You will find figures quoted online. They are difficult to verify, for a specific reason.
The Standard Tables of Food Composition in Japan do not list L-theanine. The tables cover protein, fat, carbohydrate, minerals, vitamins and some amino acids — but not this one.
Which means a stated figure for a cup of tea depends on:
- The variety of tea and how it was grown (shaded or not)
- The harvest — first flush, second flush
- Water temperature, steeping time, leaf quantity
None of these are fixed. Unlike a portioned product, a cup of tea is not a defined amount.
In Ne9
Ne9 contains, per pouch:
| Caffeine | 150mg |
| L-theanine | 75mg |
| Nicotine, tobacco, sugar | None |
Both amounts are printed on the lid of the can, so they are readable when buying and when using.
Ne9 is a food — confectionery powder sealed in non-woven fabric. It is held in the mouth without chewing or swallowing, and removed afterwards. It is not a medicine, and it is not intended to diagnose, treat, cure or prevent any disease.
Frequently asked questions
Is L-theanine only in tea?
It is found in the tea plant and in a small number of other species. In everyday food terms, tea is the main source.
What is the difference between L-theanine and theanine?
"Theanine" is the general name; "L-theanine" specifies the molecular form found in nature. Labels use both.
Why is it combined with caffeine?
They occur together in the same tea leaves. Ne9 lists both amounts on the pack so that what you are taking is countable.
How much L-theanine is in a cup of green tea?
There is no reliable single figure. The Japanese food composition tables do not list it, and the amount varies with the tea, the growing method and how it is steeped.
Is there a daily guideline for L-theanine?
Japan has no established upper limit for L-theanine in foods. There is a guideline for caffeine — around 400mg a day for a healthy adult, with up to 200mg in a single serving (European Food Safety Authority).
For the format itself, see what is a caffeine pouch. For how a day's caffeine adds up, see how much caffeine a day is the guideline.