A study compared matcha, a highly caffeinated green tea, to other sources of caffeine. Which had the greatest cognitive benefits?
Matcha is a powdered green tea concentrate that has 3 times the caffeine of regular tea, and a new study suggests it has a more long-lasting effect on cognitive performance.1
Matcha contains several ingredients that improve cognition. In addition to caffeine, it has the glutamatergic amino acid l-theanine and polyphenols catechins. L-theanine enhances the cognitive effects of caffeine while also lowering some of caffeine’s side effects, such as anxiety, tachycardia, hypertension, and insomnia, according to several controlled trials.2-5 Catechins protect the brain from oxidative stress, and preclinical studies suggest they may prevent cognitive decline.6
This study randomized 51 older Japanese adults to 3 groups that received daily supplements of either matcha, caffeine 66 mg (equivalent to the caffeine in matcha), or placebo over 3 months. The supplements were disguised in green capsules. Meanwhile, the 50- to 69-year-old subjects continued their usual intake of coffee or tea (a cup a day on average, which did not significantly change during the trial).
The investigators tested cognition before the intervention, after the first dose, and again after 3 months of daily dosing. However, the subjects did not take the caffeine or matcha on the final day of testing, so any benefits seen after 3 months were likely sustained from prior dosing.
The primary outcomes were measured by the Uchida–Kraepelin, a timed arithmetic test, and the Cognitrax, a computerized battery that tests memory, attention, reaction time, response-inhibition, and facial recognition. A weakness of the study is the use of multiple measures, which can lead to random false positives, a problem they tried to minimize with the Bonferroni correction.
After a single dose, both caffeine and matcha improved tests of attention, speed, and reaction time, including the Uchida-Kraepelin arithmetic test. Other tests were not affected, such as memory, response-inhibition, and facial recognition. But after 3 months of regular use, caffeine’s benefits on the arithmetic test shrank to a non-significant level, while matcha’s grew, as shown in the graphs above.
The Uchida-Kraepelin arithmetic test has an interesting backstory. It was developed by the pioneering psychiatrist Emil Kraepelin, MD, who used it to screen job applicants at his hospital in Munich. Today, it is widely used to by Japanese corporations to screen job applicants. The test requires subjects to answer simple arithmetic questions as fast as possible over 30 minutes, divided into 2 15-minute blocks. It is thought to measure cognitive performance under stressful conditions. Notably, l-theanine has specific benefits in the stress-response.3
The Bottom Line. Matcha is a low-risk intervention that may augment caffeine’s cognitive-boosting effects in 2 ways. First, it reduces anxiety under stressful conditions, an effect confirmed in multiple studies of L-theanine. Second, it may be less vulnerable to tolerance with regular use, but that finding awaits additional confirmation. Green tea and matcha have other health benefits as well: improving metabolic and cardiovascular health, reducing cancer risk, and preventing cognitive decline.7 Its main risks are those attributable to caffeine: gastrointestinal reflux, headaches, and insomnia.
1. Baba Y, Inagaki S, Nakagawa S, et al. Effects of daily matcha and caffeine intake on mild acute psychological stress-related cognitive function in middle-aged and older adults: a randomized placebo-controlled study. Nutrients. 2021;13(5):1700.
2. Yoto A, Motoki M, Murao S, Yokogoshi H. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol. 2012;31(1):28.
3. Williams JL, Everett JM, D'Cunha NM, et al. The effects of green tea amino acid l-theanine consumption on the ability to manage stress and anxiety levels: a systematic review. Plant Foods Hum Nutr. 2020;75(1):12-23.
4. Haskell CF, Kennedy DO, Milne AL, et al. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol Psychol. 2008;77(2):113-122.
5. Kahathuduwa CN, Dassanayake TL, Amarakoon AMT, Weerasinghe VS. Acute effects of theanine, caffeine and theanine-caffeine combination on attention. Nutr Neurosci. 2017;20(6):369-377.
6. Mi Y, Qi G, Fan R, et al. EGCG ameliorates high-fat- and high-fructose-induced cognitive defects by regulating the IRS/AKT and ERK/CREB/BDNF signaling pathways in the CNS. FASEB J. 2017;31(11):4998-5011.
7. Kochman J, Jakubczyk K, Antoniewicz J, et al. Health Benefits and Chemical Composition of Matcha Green Tea: A Review. Molecules. 2020;26(1):85.