L-Theanine with Chemotherapy: Safety and Potential Benefits

L-theanine can be safely taken during chemotherapy and may potentially enhance chemotherapy efficacy while reducing certain side effects.

Safety Profile of L-Theanine During Chemotherapy

L-theanine does not appear on any contraindication lists in major oncology guidelines for chemotherapy administration 1
Unlike many herbal supplements that require holding for 2 weeks before procedures, L-theanine only needs to be discontinued 24 hours prior to surgical procedures due to its rapid metabolism 2
L-theanine does not cause dependence, tolerance, or cognitive impairment, making it safer than many conventional anxiolytics used during cancer treatment 2

Research suggests L-theanine may enhance the antitumor efficacy of certain chemotherapy agents including doxorubicin, cisplatin, irinotecan, and anthracyclines 3
L-theanine has been shown to increase chemotherapy drug concentration specifically in tumor tissues while not increasing concentration in normal tissues like heart and liver, potentially improving efficacy while reducing toxicity 4, 5
In animal models, L-theanine significantly reversed chemotherapy-induced decreases in leukocyte and bone marrow cells when combined with idarubicin, suggesting a protective effect against myelosuppression 4

L-theanine appears to inhibit the efflux of chemotherapy drugs from tumor cells, leading to increased drug concentration specifically in tumors 3, 5
The amino acid inhibits glutamate transporters in tumor cells, which reduces intracellular glutathione levels and decreases the formation of glutathione-drug conjugates that would otherwise be transported out of cancer cells 3
Recent research indicates L-theanine may induce apoptosis in tumor cells via the mitochondrial pathway, potentially enhancing the cytotoxic effects of chemotherapy 6

A recent prospective observational study (2024) found that cystine and theanine supplementation during chemoradiotherapy for non-small cell lung cancer was associated with no severe esophagitis and maintained quality of life scores 7
Patients taking medications that affect blood pressure should consult with healthcare providers before using L-theanine due to its potential hypotensive effects 2
L-theanine should be held for 24 hours before surgical procedures due to its dose-dependent decrease in blood pressure 2

While optimal dosing during chemotherapy is not established in guidelines, research studies have demonstrated benefits with doses ranging from 280-700 mg daily 7
L-theanine can be taken orally in supplement form, offering convenience compared to other relaxation therapies 2
Green tea consumption may provide similar benefits to isolated theanine supplementation when combined with chemotherapy, as demonstrated in preclinical studies 5

Patients with low blood pressure should monitor their response when beginning L-theanine supplementation 2
While evidence suggests potential benefits, patients should always inform their oncology team about any supplements they are taking, including L-theanine 1