Animal study: L-theanine extends life expectancy

The amino acid L-theanine, which is found in small amounts in tea, extends the lifespan of the worm Caenorhabditis elegans, a favourite lab animal of anti-aging researchers. The extent of the effect, which nutritionists at the University of Jena report on in the European Journal of Nutrition, is limited however.

An average cup of green tea contains about 8 mg L-theanine; an average cup of black tea contains 25 mg. Supplements usually contain several hundred milligrams. Manufacturers suggest that these supplements reduce feelings of stress in a natural way and improve brain function.

In addition to this, there are several studies that suggest that L-theanine has other effects too. Animal studies have shown for example that L-theanine makes beta-amyloid plaques less toxic. [Free Radic Biol Med. 2009 Dec 1; 47(11): 1601-10.] This would suggest that L-theanine supplementation might help inhibit Alzheimer’s.

Animal studies have also shown that L-theanine, along with caffeine and catechins, is one of the compounds in green tea that have a slimming effect [In Vivo. 2004 Jan-Feb; 18(1): 55-62.] – and that can lower blood pressure. [Biosci Biotechnol Biochem. 1995 Apr; 59(4): 615-8.] Moreover, there are human studies which have shown that supplementation with cysteine and L-theanine protect the immune system of athletes who do intensive training.

The researchers tested the life-extending effect of L-theanine on nematodes in a laboratory. They did this by adding the amino acid to the worms’ food. The graph below shows the effect of the most effective concentration. The maximal lifespan increased by 4.4 percent as a result of supplementation and average lifespan increased by 3.6 percent.


The graph above shows the life-extending effect of L-theanine on nematodes that had also been exposed to the toxic pesticide paraquat. Only the highest concentration of L-theanine was capable of extending the lifespan of the nematodes by a statistically significant amount.

“Taken together, these findings indicate that L-theanine extends Caenorhabditis elegans lifespan suggesting that this compound may be worth evaluating in mammals and potentially humans in regard to prevention of aging and age-associated diseases”, the researchers summarise.

The study was partially financed by Coca-Cola Germany.

L: -Theanine extends lifespan of adult Caenorhabditis elegans.

Zarse K, Jabin S, Ristow M.

Department of Human Nutrition, Institute of Nutrition, University of Jena, Jena, Germany.


Compounds that delay aging in model organisms may be of significant interest to anti-aging medicine, since these substances potentially provide pharmaceutical approaches to promote healthy lifespan in humans. We here aimed to test whether pharmaceutical concentrations of L: -theanine, a putative anti-cancer, anti-obesity, blood pressure-lowering, and neuroprotective compound contained in green tea (Camellia sinensis), are capable of extending lifespan in a nematodal model organism for aging processes, the roundworm Caenorhabditis elegans.

Adult C. elegans roundworms were maintained on agar plates, were fed E. coli strain OP50 bacteria, and L: -theanine was applied to agar to test (1) whether it may increase survival upon paraquat exposure and (2) whether it may promote longevity by quantifying survival in the presence and absence of the compound.

L: -theanine increases survival of C. elegans in the presence of paraquat at a concentration of 1 micromolar. L: -theanine extends C. elegans lifespan when applied at concentrations of 100 nM, as well as 1 and 10 micromolar.

In the model organism C. elegans, L: -theanine is capable of promoting paraquat resistance and longevity suggesting that this compound may as well promote healthy lifespan in mammals and possibly humans.

PMID: 22422488 [PubMed – in process]
PMCID: PMC3419347