Can L-Theanine Protect The Brain From Environmental Toxins?


Multiple studies show the potential of l-theanine protecting the brain from harmful effects of toxins

The world is filled with toxins. Chemicals such as organophosphates, flame retardants, and phthalates can be found in food, plastics, furniture, food wrap, cookware, cans, carpets, shower curtains, electronics, and even shampoo. These toxins have the potential to affect our brain. In particular, some epidemiological studies have linked environmental toxin exposure with the incidence of Alzheimer’s disease and Parkinson’s disease (9,10). While these links are not iron-clad, there is a strong possibility that exposure to modern environmental toxins can have a negative effect on brain health.

Recently, multiple publications have demonstrated that L-theanine can protect the brain from the harmful effects of toxins, both environmental and those used in laboratory settings. These effects have been demonstrated in a variety of ways, both in cell culture models and well as in living animals:

  • In a model of Huntington’s disease, where specific neurons are killed by quinolic acid injection into the brain, L-theanine attenuated the negative effects of quinolic acid injection and protected the fidelity of the damaged neurons. (1)

  • In a mouse model of neurological degeneration by Cadmium poisoning, L-theanine inhibited neuronal death, and increased the levels of antioxidants and free radical scavenging enzymes.(2)

  • In a model of Huntington’s disease caused by dopamine toxicity, L-theanine protected against neuronal death and increased glutathione, one of the most important antioxidant molecules in the body. (3)

  • In a model of Huntington’s disease induced by 3-Nitroproprionic acid induced toxicity, L-theanine prevented inflammation and neurotransmitter aberrations when administered prior to acid injection. (4,7)

  • In a model of oxidative damage caused by Aroclor, a discontinued chemical sold in the US from 1930-1977, L-theanine reversed inflammation, increased antioxidants, and protected against neuronal death. (5)

  • In another model of oxidative brain injury by aluminum chloride, L-theanine increased antioxidant enzymes, and rescued pathological brain alterations caused by the aluminum toxicity. (6)

  • In a study of environmental toxins rotenone and dieldrin, L-theanine rescued DNA fragmentation and cell death in a cell culture model. (8)

These and other studies point to L-theanine exerting varied neuroprotective activities that can reduce the potential harmful effects toxins in the enviroment have on our brain.

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Authored by Sumeet Sharma


1: Jamwal S, Singh S, Gill JS, Kumar P. L-theanine prevent quinolinic acid induced motor deficit and striatal neurotoxicity: Reduction in oxido-nitrosative stress and restoration of striatal neurotransmitters level. Eur J Pharmacol. 2017

2: Ben P, Zhang Z, Zhu Y, Xiong A, Gao Y, Mu J, Yin Z, Luo L. l-Theanine attenuates cadmium-induced neurotoxicity through the inhibition of oxidative damage and tau hyperphosphorylation. Neurotoxicology. 2016

3: Takeshima M, Miyazaki I, Murakami S, Kita T, Asanuma M. l-Theanine protects against excess dopamine-induced neurotoxicity in the presence of astrocytes. J Clin Biochem Nutr. 2016

4: Jamwal S, Kumar P. L-theanine, a Component of Green Tea Prevents 3-Nitropropionic Acid (3-NP)-Induced Striatal Toxicity by Modulating Nitric Oxide Pathway. Mol Neurobiol. 2017

5: Sumathi T, Asha D, Nagarajan G, Sreenivas A, Nivedha R. L-Theanine alleviates the neuropathological changes induced by PCB (Aroclor 1254) via inhibiting upregulation of inflammatory cytokines and oxidative stress in rat brain. Environ Toxicol Pharmacol. 2016

6: Sumathi T, Shobana C, Thangarajeswari M, Usha R. Protective effect of L-Theanine against aluminium induced neurotoxicity in cerebral cortex, hippocampus and cerebellum of rat brain - histopathological, and biochemical approach. Drug Chem Toxicol. 2015

7: Thangarajan S, Deivasigamani A, Natarajan SS, Krishnan P, Mohanan SK. Neuroprotective activity of L-theanine on 3-nitropropionic acid-induced neurotoxicity in rat striatum. Int J Neurosci. 2014

8: Cho HS, Kim S, Lee SY, Park JA, Kim SJ, Chun HS. Protective effect of the green tea component, L-theanine on environmental toxins-induced neuronal cell death. Neurotoxicology. 2008

9: Manivannan, Y., Manivannan, B., Beach, T. G., & Halden, R. U. (2015). Role of Environmental Contaminants in the Etiology of Alzheimer's Disease: A Review. Curr Alzheimer Res, 12(2), 116-146.

10: Pan-Montojo, F., & Reichmann, H. (2014). Considerations on the role of environmental toxins in idiopathic Parkinson’s disease pathophysiology. Transl Neurodegener, 3.

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