How much theanine is in tea?

 

I just looked this up related to someone bringing it up in a biohacking group, of course related to taking it as a pill supplement instead of drinking tea.  Those people love supplements, the more experimental the better, it sometimes seems.  Theanine should be harmless enough, in a normal dosage range.  But what is that?

WebMD says this; they would never steer you wrong:

L-theanine is naturally found in tea and some mushrooms. As medicine, L-theanine has most often been used by adults in doses of 200-400 mg by mouth daily for 4-8 weeks. Speak with a healthcare provider to find out what dose might be best for a specific condition.

People in that group said that 100 mg is probably ok for a starter dose, but if they mean to take that twice a day it's back to 200.  It would depend on why someone is taking it.  WebMD says this:

Possibly Effective for:  Memory and thinking skills (cognitive function). Taking L-theanine by mouth might help healthy people stay focused. It isn't clear if adding L-theanine to caffeine works better than using either of those ingredients alone.

There is interest in using L-theanine for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Healthline said this, more in line with what those people in that group were using it for:  

It’s said to help ease anxiety, stress, and reduce insomnia.  Before trying it out yourself, learn more about the potential health benefits, as well as any possible risks or complications.

So those two not so reliable, light content health sites said completely opposite things; that can happen.  People in that group thought that it could provide different benefits, and were taking it for different reasons.

So how much is in tea, especially in relation to standard supplementation amounts?  Scanning a few sources turned up different measured amounts, but this seems kind of middle of the road for other results:

Theanine and Caffeine Content of Infusions Prepared from Commercial Tea Samples

Materials and Methods:

Theanine and caffeine contents of 37 commercial white, green, oolong, black, and pu-erh tea samples were quantified by high-performance liquid chromatography-diode array detector.

Results:

The mean L-theanine content of white, green, oolong, and black teas were 6.26, 6.56, 6.09, and 5.13 mg/g, respectively. The same values for caffeine content were 16.79, 16.28, 19.31, and 17.73 mg/g.

So just over 6 mg per gram of dry tea.  The caffeine values seem normal enough; measured amounts typically ranges between 15 and 25 mg/g, so maybe a little on the low side, but these are "commercial" products, probably low to medium low in quality level.  Both theanine and caffeine range might bump a little in relation to testing or consuming slightly better tea, but probably not too much.

Extraction rate could be a little clearer, but it seems to follow the same pattern as for caffeine, so for a relatively complete brewing process something like 90% may be extracted, possibly a little less:

So from there it's really down to daily intake, amount of dry leaf prepared per day, which is going to vary for everyone.  Someone could brew two rounds of tea a day and consume 10 grams, but I tend to brew 9 or 10 grams for each Gongfu brewing session.  10 grams at 6 mg / gram of extraction (which may be slightly lower) is 60 mg; not a lot, in relation to taking supplements, which again might be in a range of 200 mg per day (taken as pills), but that would just depend.

It's interesting that they seemed to test one pu'er sample and found no theanine in it.  That could be an anomaly, or it could be that they tested shou pu'er and fermentation really does transition that compound to become something else.  Here is that summary:

Those results are all over the place.  There may well be a correlation between theanine levels and buds and fine leaves content, versus older leaves, as there is for caffeine level, but you can't really spot an underlying cause input from this kind of list.  It would seem natural for there to be a divide between variety Sinensis and variety Assamica plants, but this definitely wasn't set up to isolate that input, or any other, really.  One sample of any given type doesn't even tell you with any certainty that other samples of the same type would follow the same pattern, and have a similar amount in them.

For me it's enough to have as a guess that we might be ingesting around 6 mg per gram of tea, since I'm not even sure what theanine would do anyway.  There's a vague understanding that it calms you while caffeine gives you a lift, so I guess a very mild speedball effect, but not much of one.  The effect would be limited if your daily consumption probably lands between 60 and 120 mg per day, and only that higher level based on drinking 20 grams worth of tea a day, which is a lot.

I glanced at a couple of other studies and they're in this general range, with some showing some black tea amounts that are a good bit higher (in this study example):

High levels of milk resulted in a marked lowering of the level of detectable l-theanine. Contrary to previous research, a standard (200 ml) cup of black tea was found to contain the most l-theanine (24.2 ± 5.7 mg) while a cup of green tea contained the least (7.9 ± 3.8 mg).

So their findings were way off that other scale, which is more typical of what other sources that I looked through were saying.  It can be confusing comparing amount per brewed cup with a derived amount per gram of dry leaf, which to me is easier to work with.  They seemed to be making tea from a standard 2 or 2 1/2 gram commercial tea bag, and then infusion time surely would've been a limitation to extraction, since you don't brew tea bags for 10 minutes.  The point here is more that studies vary on general findings, as that one study varied quite a bit in relation to measured amounts and individual tea versions, even within type categories (black, green, and so on).

Someone could keep digging if they really wanted to know, but it would be hard to factor in what these studies are not testing for:  theanine amounts in relation to tea plant material type (buds, fine leaves, old leaves), and related to tea quality level.  Guessing that a final average experienced result is around 6 grams per gram of dry tea seems good enough, with extracted amount probably just below that.  

We're taking in a significant amount of theanine when drinking tea, just not getting dosed on the high side compared to the range of 100 mg to 400 mg of intake per day.  20 grams of tea--a good bit to drink in one day, which probably would exceed that 100 mg theanine input level--might work out to 20 mg of caffeine per dry gram of ingested tea, or 400 mg of caffeine per day, the general recommended daily limit.  

That is on the high side of most caffeine level test findings; 15 to 20 grams per mg is probably a more standard range, with extraction potentially between 85 and 90%.  My point in venturing into this second tangent is that it seems that you can drink 20 grams worth of tea per day, related to not exceeding a standard caffeine input level.  Then a daily dose of over 100 mg of theanine might offset some negative effects of caffeine, feeling "jittery," as people understand might happen.  It's not completely clear that would occur, but then theanine and caffeine aren't necessarily the only two active compounds in tea, the only two that would have any effect on how you feel.