What is L-Theanine and can it help you focus?

Summary

Some studies suggest L-theanine can boost focus, especially when combined with caffeine, while other studies indicate L-theanine alone may have limited effects on attention.

Introduction

L-theanine, an amino acid found in tea leaves, is often studied for its potential cognitive benefits, particularly in enhancing focus and attention. This synthesis examines the evidence from multiple research papers to determine whether L-theanine can boost focus.

Key Insights

• Improvement in Sustained Attention and Cognitive Performance:

  • L-theanine, alone or in combination with caffeine, has been shown to improve sustained attention and overall cognitive performance in children with ADHD by decreasing mind wandering.

  • In healthy adults, L-theanine combined with caffeine improves hit rate and target discriminability in attention tasks, suggesting enhanced focus.

• Reduction in Mind Wandering:

  • L-theanine and its combination with caffeine decrease task-related fMRI reactivity of the default mode network, which is associated with mind wandering, thereby improving attention to target stimuli.

• Dose-Dependent Effects on Attention:

  • Higher doses of L-theanine (e.g., 400 mg) significantly reduce the latency of attentional event-related potentials, indicating enhanced attentional processing.

• Enhanced Task Performance:

  • Combining L-theanine and caffeine improves performance on attention tasks, such as task switching and visual stimulus discrimination, by reducing reaction times and increasing accuracy.

• Synergistic Effects with Caffeine:

  • The combination of L-theanine and caffeine shows synergistic effects in improving attention and reducing impulsivity, which is more effective than either substance alone.

• Cancer-related Benefits:

  • Studies indicate that L-theanine has anticancer properties, including the inhibition of cancer cell proliferation, metastasis, and migration, as well as the induction of apoptosis in cancer cells.

• Immune System and Metabolic Regulation:

  • L-theanine can enhance immune function and regulate metabolic processes, showing potential benefits in conditions like obesity and type 2 diabetes.

Conclusion

L-theanine, primarily found in green tea, offers multiple health benefits. It effectively reduces stress and anxiety, enhances cognitive function and mood, and provides neuroprotective and psychotropic effects. It has antioxidant, anti-inflammatory, and anticancer properties and can positively influence immune function and metabolic health. Further research, particularly long-term and large-scale human trials, is needed to fully substantiate these benefits and understand the underlying mechanisms.

Sources:

1. C. Kahathuduwa et al. "L-theanine and Caffeine Improve Sustained Attention, Impulsivity and Cognition in Children with Attention Deficit Hyperactivity Disorders by Decreasing Mind Wandering (OR29-04-19).." Current developments in nutrition, 3 Suppl 1 (2019).

2. S. Kelly et al. "L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance.." The Journal of nutrition, 138 8 (2008): 1572S-1577S .

3. C. Kahathuduwa et al. "l-Theanine and caffeine improve target-specific attention to visual stimuli by decreasing mind wandering: a human functional magnetic resonance imaging study.." Nutrition research, 49 (2018): 67-78 .

4. Y. Baba et al. "Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study." Journal of Medicinal Food, 24 (2021): 333 - 341.

5. T. Dassanayake et al. "L-theanine improves neurophysiological measures of attention in a dose-dependent manner: a double-blind, placebo-controlled, crossover study." Nutritional Neuroscience, 25 (2020): 698 - 708.

6. Ming-Yue Li et al. "L-Theanine: A Unique Functional Amino Acid in Tea (Camellia sinensis L.) With Multiple Health Benefits and Food Applications." Frontiers in Nutrition, 9 (2022).

7. Sara Shojaei‐Zarghani et al. "Theanine and cancer: A systematic review of the literature." Phytotherapy Research, 35 (2021): 4782 - 4794.

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