Green tea has an amazing array of health benefits, but a number of clinical studies have added one more: better brain health. Green tea can, apparently, protect our brains from mental decline and injury, as well as improve working memory and cognitive function. How? Based on research findings, it’s the antioxidants, phenols, polyphenols and Epigallocatechin gallate polyphenols (aka EGCGs) that are protecting and improving the brains of green tea drinkers.
Green Tea Research
A 2000 study published in Brain Research Bulletin examined whether green tea could protect against ischemia/reperfusion-induced brain injury, by minimizing one of its known causes – eicosanoids accumulation and oxygen radical-induced oxidative damage in the brain.
The subjects, Wistar rats, were given a 0.5% green tea extract orally for 3 weeks before ischemia was induced. (The researchers cut off the flow of blood in the Wistar rats’ middle cerebral arteries for 60 minutes and then actively restored the flow of blood for another 24 hours.) The animals given the green tea extract suffered significantly less brain damage than those that were not. In addition, it appeared to aid the subject’s recovery from their brain damage.
“Green tea extract pretreatment also promoted recovery from the ischemia/reperfusion-induced inhibition of active avoidance. The present study shows that the minimizing effect of green tea extract on the eicosanoid accumulation and oxidative damage in addition to the reduction of neuronal cell death could eventually result in protective effect on the ischemia/reperfusion-induced brain injury and behavior deficit.”1
A 2006 human study, published in The American Journal of Clinical Nutrition, also verified green tea’s usefulness in protecting brain health. The authors concluded that “higher consumption of green tea is associated with a lower prevalence of cognitive impairment in humans.”2
A 2014 study published in the journal Psychopharmacology showed that green tea not only protected the brain, it also improved working memory and cognitive performance. The authors believed that green tea might also be effective in the treatment of dementia. Here’s a quote:
“Our findings provide first evidence for the putative beneficial effect of green tea on cognitive functioning, in particular, on working memory processing at the neural system level by suggesting changes in short-term plasticity of parieto-frontal brain connections. Modeling effective connectivity among frontal and parietal brain regions during working memory processing might help to assess the efficacy of green tea for the treatment of cognitive impairments in psychiatric disorders such as dementia.”3
What makes green tea special?
To reiterate, green tea contains antioxidants, phenols, polyphenols and EGCGs. Other teas contain these as well. Black tea, for example, which comes from the same plant (Camellia sinensis), is processed differently, and so contains less of some of these substances. According World of Tea, catechins are in all tea, but it’s the controlled oxidation of each variety that changes the composition of catechins in each tea. The longer a tea’s oxidation period, the lower the amount of catechins in the finished tea.
“[Oxidized] black tea has fewer catechins but an abundance of EGCG polyphenols, while green tea, because it’s not oxidized, is full of catechins – naturally occurring polyphenols that are catching the attention of the world of science. … Overall, tea has about eight to 10 times more polyphenols than fruits and vegetables, but because it’s the catechins that researchers believe are the keys to tea’s health benefits, green tea is what they’ve focused on most in studies.”4
So, green tea has about the same amount of EGCGs as black teas, but more phenols, catechins, other polyphenols and antioxidants, because it is less processed / oxidized.
How Much Green Tea Do We Need?
Studies have shown benefits for those who consumed green tea 1-6 days per week. Other studies show benefits for those who drank green tea three or fewer days per week. Let’s average that out to 2-4 days per week minimum if your goal is achieving better brain health and protecting your brain from future injury. However, as numerous studies have demonstrated, the more green tea you drink the better the results.
According to cancer epidemiology researcher, Dr. Zuo Feng Zhang, and researchers at the University of Maryland Medical Center, we should drink 2 to 3 teacups (not mugs) each day, if we want to gain green tea’s health benefits. Even five teacups a day is not considered too much. In fact, “drinking up to five cups a day has been shown to decrease risk for stomach cancer.”5
How Much Green Tea Is Too Much?
10 cups of green tea is considered the upper limit for daily consumption. Green tea naturally contains caffeine and, therefore, is a stimulant. If you are caffeine sensitive or have difficulty falling asleep, even 8 cups of green tea per day may be way too much for you. Fortunately, there are decaffeinated green teas available.
There are other precautions and possible drug interactions you should keep in mind when drinking green tea as well. For a complete list, read the article “Green Tea”, on the University of Maryland Medical Center’s website. You’ll discover many other interesting facts and historical information about the light and slightly sweet beverage.
1 JT Hong, SR Ryu, HJ Kim, JK Lee, et al. “Neuroprotective effec1805t of green tea extract in experimental ischemia-reperfusion brain injury”. Brain Research Bulletin, December 2000. Web. September 2016
2 S Kuriyama, A Hozawa, K Ohmori, T Shimazu, et al. “Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project.” The American Journal of Clinical Nutrition, February 2006. Web. September 2016
3 A Schmidt, F Hammann, et al. “Erratum to: Green tea extract enhances parieto-frontal connectivity during working memory processing”. Psychopharmacology, March 2014. Web. September 2016
4 Mercola, Joseph, MD. “Green Tea Linked to Decreased Risk for Dementia”. Mercola, April 23, 2015. Web. September 2016
5 May, Susi. “Is It Possible to Drink Too Much Green Tea?” Health Magazine, August 20, 2013. Web. September 2016
Ehrlich, Steven D, NMD. “Green Tea”. University of Maryland Medical Center, November 6, 2015. Web. September 2016