Introduction to Japanese Green Tea and Diseases Related to the Brain Such as Dementia and Alzheimer's

Several diseases affect the cognitive functions of the brain. Mild Cognitive Impairment or MCI is a relatively minor impairment in memory and thought process.

Dementia is a more severe decline of these functions. Alzheimer's disease is the most common type of dementia, which happens when proteins and fibers build up in your brain and block nerve signals, destroying nerve cells.

Dementia is a significant disease and social issue in all countries with aging populations. Singapore is no exception, with 1 out of 10 seniors above the age of 60 having the disease [1].

Japanese Green tea has shown its effectiveness in preventing Dementia and Mild Cognitive Impairment (MCI). In this article, we'll dive into the details.

This article was last modified December 11th, 2022. by Yuki

The Aging of the Brain

Firstly, let's look into how the brain ages in the first place.

The nerve cells in the brain rapidly develop until about five years old and will continue to grow until 20 years old.

In the 30s to 40s, the brain will gradually shrink, initiating the brain's aging. The number of new cells developing in the brain will decrease, causing a decline in the ability to learn and memorize.

In the case of dementia, the activity of the nerve cells and the quantity steeply decline. Some causes of dementia may be genetic. However, for most patients, the brain's aging is the leading cause, and environmental and lifestyle factors work as additional factors affecting the disease.

Therefore to prevent dementia, it is crucial to slow down the brain's aging and improve the environmental and lifestyle factors surrounding us. [2]

How Japanese Green Tea can help Prevent the Aging of the Brain

Let me introduce some studies conducted in this area.

A study based on 1,003 Japanese people aged 70 or above observed that a higher frequency of green tea consumption was associated with a lower occurrence of cognitive impairment.

According to the research, people who drank two or more cups of green tea daily had a smaller chance of having cognitive impairment. [3]

A different study conducted with 723 Japanese participants aged 60 years or older in Nakajima, Japan, also showed significant positive effects of drinking green tea daily.

It indicated that the ratio for the incidence of dementia was 0.26 among individuals who consumed green tea every day compared with those who did not consume green tea at all.

The incidence of cognitive decline (Dementia and MCI) was 0.32 among those who drank green tea every day and 0.47 for those who drank 1-6 cups a week compared with those who did not consume green tea at all. [4]

These studies show that Japanese green tea significantly affects the health of the aging brain.

How does Green Tea Help Reduce the Aging of the Brain?

The mechanism of how the nutrients of green tea work in the brain itself is still not completely understood.

However, we know that the EGCG in Japanese green tea can penetrate the blood-brain barrier and into the brain within 2-3 hours after consumption, causing the improvement of learning activities. [5]

EGCG is a type of polyphenol which is found in Japanese green tea. It is one of the "green tea catechins" that carries most of green tea's remarkable health benefits. In this case, the EGCG helps improve the brain as well.

Additionally, one of the byproducts of EGCG also affects the brain.

A compound called EGC-M5 is generated more than 8 hours after the consumption of green tea. It is observed that this also reaches and helps activate the brain. [6]

In summary, 2-3 hours after consuming green tea, the EGCG will reach the brain to activate the brain cells. Additionally, more than 8 hours after drinking green tea, the byproducts of EGCG will also enter and activate the brain cells.

Scientists believe these mechanisms help suppress the aging of the brain.

The Potential of Myricetin in Preventing Alzheimer's Disease

A patient with Alzheimer's disease is known to have a buildup of what is called the "Amyloid Beta Protein" within the brain. The buildup of this protein is believed to be the cause of the disease.

Myricetin, a type of polyphenol found in green tea, is observed to have effectiveness in inhibiting the growth of this buildup. [6]

While the science is still ongoing, there may be a possibility that the Myricetin in green tea also prevents Alzheimer's disease.

Best Tea to Drink for EGCG

Here we'll focus on how to maximize the EGCG intake.

Japanese green tea is known to have some of the highest amounts of EGCG in the world. Among the several available types of Japanese green tea, Sencha and Tamaryokucha are the types of tea that contain the highest amounts of EGCG.

Especially Sencha is a standard type of Japanese green tea. It should be easy to find a suitable Sencha around you.

Although green tea can come in different forms, try to find loose-leaf Sencha as much as possible.

There is bottled green tea, but they contain significantly fewer catechins than infused loose-leaf tea. On average, the amount of catechin in infused loose-leaf tea can be 5.5 times that of a bottled green tea drink. [7]

Avoiding teabags may be a good idea as well. Recent studies have shown that plastic teabags release billions of microplastic and millions of nano plastic particles into the tea. Although the health effects of ingesting these particles are still unknown, it is a very concerning discovery. [8]

Infuse with boiling water to maximize EGCG

EGCG is a nutrient that is relatively difficult to dissolve in water. It only starts to dissolve from around 80 degrees Celsius. Therefore, one way to maximize the EGCG intake is to infuse using boiling water.

Multiple infusions of the same loose-leaf tea are also effective. Similar amounts of EGCG can be extracted in the second infusion to the first. The third infusion will typically show a sharp decline in catechins. Therefore, conducting two infusions of Sencha may be the most efficient.

Author Yuki


Yuki is the Editor-in-Chief AND Community Manager at Tealife. He bleeds Japanese Tea and loves being a part of the Japanese Tea journey of others. Writes, does events, conducts tasting sessions, drinks, drinks and drinks tea! Easily accessible - hit him up on whatsapp (+65) 85882980.


[1] "MOH | News Highlights." MOH | News Highlights, 22 Aug. 2017,

[2] Yang, J., et al. "Tea Consumption and Risk of Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis Update." BMJ Open, vol. 4, no. 7, BMJ, July 2014, pp. e005632–e005632. Crossref,

[3] Iso H, Date C, Wakai K, Fukui M, Tamakoshi A; JACC Study Group. The relationship between green tea and total caffeine intake and risk for self-reported type 2 diabetes among Japanese adults. Ann Intern Med. 2006 Apr 18;144(8):554-62. doi: 10.7326/0003-4819-144-8-200604180-00005. PMID: 16618952.

[4] Ma Q, Chen D, Sun HP, Yan N, Xu Y, Pan CW. Regular Chinese Green Tea Consumption is Protective for Diabetic Retinopathy: A Clinic-Based Case-Control Study. J Diabetes Res. 2015;2015:231570. doi: 10.1155/2015/231570. Epub 2015 Oct 11. PMID: 26539551; PMCID: PMC4619946.

[5] お茶の健康効果20選