How to Drink Japanese Green Tea To Reduce the Risk of Diabetes

Not only is Diabetes a severe disease, but it is also a serious social and economic issue.

According to MOH [1], in Singapore, Diabetes is a serious health concern. Over 400,000 Singaporeans are living with the disease. One in three Singaporeans has a lifetime risk of getting Diabetes, and the number of those with Diabetes is projected to reach one million by 2050.

The good thing is that lifestyle changes can prevent Diabetes, and Japanese Green Tea may play a significant role.

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

Introduction to Diabetes

Not only is Diabetes a severe disease, but it is also a serious social and economic issue.

According to MOH [1], in Singapore, Diabetes is a serious health concern. Over 400,000 Singaporeans are living with the disease. One in three Singaporeans has a lifetime risk of getting Diabetes, and the number of those with Diabetes is projected to reach one million by 2050.

The good thing is that lifestyle changes can prevent Diabetes, and Japanese Green Tea may play a significant role.


How effective is drinking tea in preventing Diabetes?

Several human-based studies support the effectiveness of Japanese green tea in preventing Diabetes.

A large-scale human-based study in Japan suggests that a person who drinks six or more cups of Green Tea per day has a 33% lower risk for Type 2 Diabetes than a person who drinks less than one cup per week. [3]

Another large-scale meta-analysis in several countries, including Singapore, suggested that daily tea consumption of three or more cups daily is associated with a 16% reduction in Type 2 Diabetes risk. [2] (This study is based on a wider variety of tea, including black and oolong tea)

Furthermore, a study based on Chinese green tea has shown that drinking tea significantly reduces the risk of Diabetic Retinopathy in Diabetic patients. Diabetic Retinopathy is an eye condition that can cause blindness and vision loss in people with Diabetes. It suggests that a weekly drinking habit of Chinese green tea reduces the risk of Diabetic Retinopathy by 50%. [4]

While it is still too early to conclude that Green Tea is effective in preventing Diabetes, these studies indicate its potential.

At the very least, they show that it is worth incorporating green tea into your daily habits.

Let's look into the scientific mechanisms behind how Japanese Green Tea is thought to help prevent Diabetes.


How does Green Tea help prevent Diabetes?

The key nutrient of tea that helps reduce the risk of Diabetes is EGCG or Epigallocatechin Gallate. This nutrient is one of the four Green Tea Catechins found in Green Tea and is arguably the most potent regarding health benefits.

The key to preventing Diabetes is lowering the blood sugar level. There are several mechanisms by which EGCG helps this.

Here is a highly abbreviated summary of the six mechanisms.

      1. It inhibits α-amylase and α-glucosidase, which are enzymes that cause glucose absorption.
      2. It inhibits Gluconeogenesis, or the generation of glucose, in the Liver.
      3. It inhibits Glucose absorption in the small intestines.
      4. It promotes insulin to be generated by the pancreatic beta cells, which lowers blood sugar concentration.
      5. It improves insulin sensitivity (which also helps reduce blood sugar concentration)
      6. A recent study shows that metabolites produced from EGCG also inhibit glucose absorption, highlighting a new mechanism on how tea may help Diabetes. [5]

The Type of Green Tea to Drink for EGCG

Out of all the different types of Green Tea, which tea should I choose to maximize EGCG?

Firstly, focusing on Japanese Green Tea is the right approach if you're looking for EGCG. Japanese Green tea contains one of the highest levels of EGCG in the world.

There are several types of Japanese Green tea, but if you're looking to maximize the EGCG content, it's best to go for Sencha or Tamaryokucha.

Funmatsu-Ryokucha is also an option, but it comes with a caveat. It may be too bitter to continue daily.

Sencha and Tamaryokucha

The Sencha and Tamaryokucha are the most basic forms of Japanese Green Tea. They are steamed to stop oxidation and come in a loose-leaf format.

They don't undergo "shading" from the sun during cultivation or additional processing after its manufacturing. Preserving the natural state of tea leaves in the form of Sencha and Tamaryokucha best maximizes the EGCG content.

Different grades of tea will result in varying levels of EGCG. So which grade has the highest levels? The answer may be counter-intuitive, but lower grades of tea show higher EGCG levels.

This is because EGCG constitutes the astringency of Green Tea. The higher the volume of EGCG within the tea, the more astringent it will become.

While astringency is considered a pleasurable taste component of Japanese Green tea, high levels of astringency are challenging to drink and therefore are regarded as a lower grade for Japanese tea.

It's considered that the first flush leaves, or the Ichibancha, will have lower levels of EGCG compared to Nibancha or second flush leaves.

The key to choosing the best Tea for EGCG is finding a balance of high levels of EGCG while also having good taste so you can enjoy it daily. The persistence in drinking green tea daily is more important than the single consumption of EGCG.

The key is to enjoy!

Funmatsu-Ryokucha

The Funmatsu-Ryokucha is a powdered form of Green Tea.

The benefit of Funmatsu-Ryokucha is that since it is a powdered form, it dissolves in water, and you can absorb 100% of the nutrients of the Tea leaves.

Infusing tea only extracts 40-60% of the tea's nutrients. However, by taking a powdered form and directly consuming the leaves by dissolving them in water, you can absorb 100% of the nutrients.

Unlike Matcha, which is also powdered, the tea leaves are not shaded from the sun. Therefore it contains similar levels of EGCG to Sencha and Tamaryokucha.

The only issue is that it may be too repelling to drink!

Since this is drinking the tea leaves directly, it may be too astringent.

If it is, stick to loose-leaf forms such as Sencha and Tamaryokucha so you can continue as a daily habit.


How to Prepare Tea to Maximize EGCG

For loose-leaf tea, including Sencha and Tamaryokucha, the preparation affects the amounts of EGCG you can absorb.

EGCG is a substance that dissolves better at temperatures of 80 degrees Celsius or higher.

This nature of tea is why several Japanese Green tea instructions indicate infusing tea in temperatures of 80 degrees Celsius or lower. The idea is to reduce the amount of EGCG in the tea to reduce the astringency while still extracting umami to enjoy the tea.

However, if you're objective is to intake EGCG, your approach should be the exact reverse. Infusing tea using boiling water can maximize the amount of EGCG extracted.

Again this comes with a caveat. If you feel this is too astringent for you, you may not be able to continue it as a daily habit.

In that case, you should lower the temperature to reach astringency levels acceptable to you.

Author Yuki

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.


References

[1] "MOH | News Highlights." MOH | News Highlights, 22 Aug. 2017, www.moh.gov.sg/news-highlights/details/diabetes-the-war-continues.

[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, https://doi.org/10.1136/bmjopen-2014-005632.

[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