Top 6 Proven Health Benefits of Theanine

Theanine is a powerful amino acid that protects both the heart and brain, among other health benefits. Read more below to learn about all of its properties.



Theanine is an amino acid that is mostly found in tea leaves and fungi. It is used to help improve mood and lower stress, and to protect the brain and heart (R).

Theanine usually refers to L-theanine, which has more health benefits compared to D-theanine. It is mostly found in tea (R).

My Experience With Theanine and Recommendation

Theanine is relaxing for me, but not too sedating.  It’s a good relaxer that doesn’t decrease cognitive performance.

I recommend:

  • Theanine (suntheanine) (AMZN) (no excipients)
  • Theanine (suntheanine) (IHERB)

Health Benefits of Theanine

1) Theanine Reduces Anxiety


After participants took L-Theanine, they had to do mental tasks. Compared to the patients who took a placebo, they had lower stress symptoms and reduced heart rates (R).

Daily supplementation in schizophrenic patients leads to reduced anxiety (R).

It also promoted relaxation in healthy patients (R).

2) Theanine Improves Brain Function

L-Theanine supplementation can help increase attention and improve memory.

In men and women who suffered from minor brain damage, a combination of L-theanine and green tea extract improved memory during a mental exercise. It did so by increasing delayed recognition during a memory test (R).

The subjects’ attention span and alertness increased during the memory test as well (R).

3) Theanine Protects the Heart


Tea consumption can help reduce the risk of heart attack, heart disease, and stroke.

Three cups of tea a day reduced the rate of heart attacks by 11% in European patients (R).

In elderly Japanese patients, green, black, and oolong tea consumption reduced the rate of death from heart disease. The patients also had fewer strokes and fewer heart attacks compared to ones who drank coffee (R).

4) Theanine is an Antioxidant

The L-theanine in tea exerts a dose-dependent antioxidant effect (R).

The amino acid also restored the antioxidant capability of liver cells, which helps prevent liver injuries (R).

In rats, it dose-dependently decreased oxidative damage and stopped inflammation (R).

5) Theanine Increases Sleep Quality


ADHD can cause sleep disturbances. Boys who took two 200 mg doses of L-Theanine daily for six weeks had a higher quality of sleep compared to ones who took a placebo (R).

They had higher sleep percentages and better sleep efficiency. Supplementation also decreased the amount of time the participants were awake after sleep started (R).

6) Theanine Reduces Symptoms of Schizophrenia

400mg daily for 8 weeks resulted in less schizophrenic symptoms. The patients’ reported lower anxiety, less sensory complaints, and fewer muscle problems (R).

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  • The kidney preferentially reabsorbed and metabolized L-Theanine. The kidney preferentially excreted D-Th (R).
  • Thus, phosphate-independent glutaminase in the kidneys hydrolyzed Theanine (R).
  • L-Theanine augmentation was associated with a reduction of anxiety (P = .015; measured by the HARS scale) (R).
  • According to the 5-dimension model of psychopathology, L-theanine produced significant reductions on PANSS positive (P = .004) and activation factor (P = .006) scores compared to placebo (R).
  • Stratified analyses showed that LGNC-07 improved memory and selective attention by significantly increasing the Rey-Kim memory quotient and word reading in the subjects with MMSE-K scores of 21-23 (LGNC-07, n = 11; placebo, n = 9) (R).


  • Tea leaves (R)
  • Japanese Camellia (R)
  • Bay Bolete mushroom (R)


When taking theanine supplements, you should pay attention to your use of other drugs.

Theanine can lower blood pressure. If you take medication for blood pressure, your blood pressure might go too low (R).

It can also lower the effectiveness of stimulant medications (R).

L-theanine can also cause dizziness, headaches, and digestive problems (R).

The appropriate dosage depends on the user’s age and health (R).

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