L-Theanine in Neuro Recall: Short-Term Focus Studies, the Dose Gap and Safety
Quick answer
L-theanine is an amino acid found in tea. Short trials in healthy adults, using 50 to 400 mg and most often 200 mg, found small gains in reaction time and attention within an hour or two, sometimes with caffeine. Neuro Recall does not print its L-theanine amount. No side effects were reported in the limited human data.
What is L-theanine?
L-theanine is an amino acid found in tea. Researchers have tested it for attention, mood and sleep, often beside caffeine, since tea contains both (Nutr Rev 2025, Payne et al., tea and L-theanine meta-analysis). Neuro Recall lists it seventh of the ten ingredients in its 635 mg blend.
- Type
- Amino acid
- Natural source
- Tea leaves
- Amount in Neuro Recall
- Not published
- Studied dose
- 50 to 400 mg; the median in theanine-only trials was 200 mg
- Studied length
- Single doses up to a few weeks, such as 200 mg a day for 4 weeks
- Studied in
- Healthy adults, on short tasks
How is L-theanine thought to work?
The sources we read do not explain how L-theanine acts in the brain, so this page sticks to what was measured. What trials tracked was timing: changes showed up within an hour or two of a dose, not after weeks.
Tea complicates the picture. A review of 21 green tea studies found the clearest effects on memory and attention when caffeine and L-theanine were combined, and said the effects of tea cannot be credited to any single part (Phytomedicine 2017, Mancini et al., Green tea and cognition). Only 4 of those 21 studies were randomized trials.
- Dose
Taken
Trials gave 50 to 400 mg, most often 200 mg.
- Hour 1
Theanine alone
Choice reaction time was faster.
- Hour 2
With caffeine
Attention accuracy was better when theanine was paired with caffeine.
- Weeks
Daily use
Some trials gave 200 mg a day for 4 weeks; sleep results were inconclusive.
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What did studies of L-theanine find?
Short trials in healthy people found small, early changes in reaction time and attention. The 2025 review behind most of these numbers warns that its confidence ranges show a lot of uncertainty (Nutr Rev 2025, Payne et al., tea and L-theanine meta-analysis).
| Question | What the 2025 review found |
|---|---|
| Theanine alone | Faster choice reaction time in the first hour |
| Theanine plus caffeine | Better attention accuracy in the second hour |
| Sleep | Inconclusive |
| Long-term memory | Not tested; effects were on short tasks |
| Dementia | Not studied |
So the honest summary is a small, short-lived nudge on timed tasks, measured in a lab. Nothing here shows a lasting change in memory, and none of these studies tested a product like this one.
What the trials leave out
Every person in the pooled trials was healthy, and many trials gave one dose before a short test. That leaves out the people most likely to shop for a memory supplement, such as older adults worried about forgetting. It also leaves open what happens over months of daily use.
Do the Neuro Recall focus claims match the L-theanine research?
Only in part. The brand graphics promise mental clarity, focus and mood support, but the theanine trials measured reaction time and attention for an hour or two, at doses the label does not confirm.
- Marketing only
Promotes mental clarity and focus
Brand graphicTheanine trials found small, short-term gains in attention. The dose here is unknown.
- Marketing only
Mood support
Brand graphicNot tested in this product.
- On the label
L-theanine
Supplement Facts panelNamed in the blend, seventh of ten.
- Not shown
Amount of L-theanine, and any caffeine
Supplement Facts panelNeither figure is printed, so the theanine-plus-caffeine results cannot be assumed.
How much L-theanine is in Neuro Recall compared with the studied dose?
Neuro Recall does not print its L-theanine amount. Its place on the label suggests it is small: likely too little for the usual 200 mg trial dose, though it could reach the 50 mg low end.
| Measure | Amount |
|---|---|
| Low end of trial doses | 50 mg |
| Median trial dose | 200 mg |
| An even split of the blend | About 63.5 mg |
| The most theanine could be, if listed by weight | About 91 mg, a seventh of the blend |
| Caffeine on the label | None printed |
| L-theanine in Neuro Recall | Not published |
Why a seventh? FDA rules ask a blend to list its ingredients from most to least by weight (FDA, Dietary Supplement Labeling Guide, Ch. IV). L-theanine comes seventh, so if the label follows that rule, six ingredients weigh at least as much, and theanine cannot be more than 635 divided by 7. That is under half the median trial dose.
Green tea extract sits two places higher on the same label; its caffeine and liver questions are on the green tea extract page. All 14 ingredients are compared in the Neuro Recall ingredients guide.
Is L-theanine safe? Side effects and who should avoid it
No side effects have been reported from taking L-theanine, but human data are limited (Memorial Sloan Kettering, L-Theanine (About Herbs)). The same source lists pregnancy and breastfeeding as reasons not to take it.
| Who | What to do | Why |
|---|---|---|
| Pregnant or breastfeeding | Do not use | L-theanine may not be safe then, and the Neuro Recall label says do not use |
| Under 18 | Do not use | The product is sold for adults |
| Taking prescription medicine | Ask a pharmacist first | Theanine interactions are not covered in our sources, and other blend ingredients have known ones |
| Sensitive to caffeine | Ask before starting | The green tea extract's caffeine content is not printed |
| New or worsening memory problems | See a doctor first | Treatable causes need checking |
Side effects for every ingredient on the label are listed on the Neuro Recall side effects page, and the daily directions are on the how to use Neuro Recall page.
What should you expect from the L-theanine in Neuro Recall?
Expect little you can count on. The trials found small, short gains at around 200 mg, and the label order suggests this blend holds well under half of that.
- Studied at 50 to 400 mg, usually 200 mg
- Likely in this blend: no more than about 91 mg
- Best-supported effect: faster reaction time within an hour
- Not shown: any lasting change in memory
The pairing with the most support in these reviews is the one tea already contains: caffeine with L-theanine. A cup of tea is a different thing from a capsule, and NCCIH reports no safety concerns for adults who drink green tea (NCCIH, Green Tea: Usefulness and Safety). If you take Neuro Recall for focus, judge it over weeks, and keep notes rather than relying on how a single morning feels.
L-theanine: questions people ask
What does L-theanine do?
In short trials of healthy adults, it was linked to faster reaction time within the first hour. With caffeine, attention accuracy improved in the second hour.
How much L-theanine should I take?
Trials used 50 to 400 mg, most often 200 mg. Ask your doctor before adding more on top of a product that already contains it.
Does L-theanine help focus?
A little, for a short time, in lab tasks. The 2025 review found small gains in attention with wide uncertainty.
Can you take L-theanine every day?
Some trials gave 200 mg a day for 4 weeks, and no side effects have been reported. Long-term human data are limited.
Does L-theanine make you sleepy?
The research does not show that. Sleep results were inconclusive, and the trials measured daytime attention.
Why is L-theanine paired with caffeine?
Tea contains both, and the clearest attention results came when they were taken together. Caffeine alone was not the focus of these trials.
What are L-theanine side effects?
None have been reported in people, though the data are limited. It is not advised in pregnancy or breastfeeding.
Does Neuro Recall contain caffeine?
The label prints no caffeine amount. It contains green tea leaf extract, and the extract's caffeine content is not stated.
How much L-theanine is in Neuro Recall?
Not published. It is one of ten ingredients in a 635 mg blend, and listed seventh, which suggests well under 200 mg.
Page check
Written by
Writes and fact-checks every page against the Supplement Facts panel, the back label and public health sources.
Medically reviewed by
Dr. Neelum Aggarwal, MD, Physician
Medical reviewer. Review date: October 12, 2026.
- Last checked October 11, 2026
- Facts from the bottle, the sales page and the sources cited above
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