By Dr. Joseph Mercola | mercola.com
STORY AT-A-GLANCE
- Data from neuroimaging and questionnaires were given to 36 healthy older individuals found drinking tea for 25 years or more had a positive effect on the function, structure, and organization of the brain, including greater functional connectivity
- Tea is one of the most popular beverages around the world, second only to water. Nearly 80% of U.S. households drink tea and, in 2018, 3.8 billion gallons of tea were served in the U.S., which still was not enough to rank the country as one of the top 10 tea consuming countries in the world
- Catechins, and specifically epigallocatechin-3 gallate (EGCG), found in tea have been associated with chemoprotective and cardiovascular protective properties and reductions in cognitive decline in aging and amyloid plaque development in Alzheimer's disease
- Store loose-leaf tea in airtight, opaque, nonreactive containers away from heat, light and strong odors. If you don't like drinking tea, consider green tea extract supplements, but take care not to consume more than you would normally from drinking tea, as overdoses are associated with significant liver damage
Tea is an ancient beverage recognized for millennia as having a dramatic and positive impact on health, as well as playing an important part in cultures around the world. For example, tea has been an integral part of British life for nearly two centuries, having started in England in 1840 when the Duchess of Bedford needed sustenance between lunch and dinner. As such, teatime began as a small snack with tea, but soon became a social gathering in the wealthy class.1
Today, teatime is an honored tradition in Great Britain for all classes, with protocols on not only how to “take tea” but when to take it and what to eat — or not eat — with it. In a fun article on British teatime, NPR2 warns: Don’t eat everything you’re offered (you don’t want to appear too hungry) and whatever you do, don’t put out your pinky when holding your cup. “It makes you look pretentious,” a British teatime expert explains.
In contrast, teatime in the West often focuses on the food — generally sandwiches and cakes — in a setting where tea appears to be more of an afterthought than the center of the event.3 Eastern culture, on the other hand, has elevated tea drinking to an art form, if for no other reason than this is where tea originated as a “pillar” of life. In China, tea has been the drink of choice for 5,000 years.4
Today, tea is one of the most popular beverages around the world, second only to water. According to the Tea Association of the U.S.A.,5 nearly 80% of all U.S. households have tea and it's the only beverage commonly served hot or cold; 84% of the tea consumed in the U.S. is black tea and 15% is green (more about the types of tea later in this article).
In 2018, 84 billion servings of tea equaling 3.8 billion gallons were served to Americans. However, despite those large numbers, the U.S. does not rank in the top 10 tea consuming countries of the world.6 That honor goes to, in order, Turkey, Ireland, United Kingdom, Iran, Russia, Morocco, New Zealand, Egypt, Poland, and Japan.
Drinking Tea May Help Develop Better Brain Connections
A recent study from the National University of Singapore has found those who regularly drink tea may experience healthier cognitive functioning.7,8 Past research already indicated that drinking tea is healthy for your brain. However, this recent study using data from neuroimaging taken of 36 older adults has a twist.
Interested in the effect tea may have on brain structure and organization, scientists gave participants a questionnaire about what they could remember about their drinking habits from age 45 into the present. Participants then underwent an MRI.
From the imaging, the researchers found that tea not only has a positive effect on brain structure, function and organization, but that those who drank the most tea — at least four times a week for about 25 years — also had greater functional connectivity strength. They did not find tea had any effect on the asymmetry between hemispheres, though.
As assistant professor Feng Lei from the National University of Singapore explained in a EurekAlert press release, connectivity is very important:9
“Take the analogy of road traffic as an example — consider brain regions as destinations, while the connections between brain regions are roads. When a road system is better organized, the movement of vehicles and passengers is more efficient and uses fewer resources. Similarly, when the connections between brain regions are more structured, information processing can be performed more efficiently.
We have shown in our previous studies that tea drinkers had a better cognitive function as compared to non-tea drinkers. Our current results relating to brain network indirectly support our previous findings by showing that the positive effects of regular tea drinking are the result of improved brain organization brought about by preventing disruption to interregional connections.”
Catechins Protect Your Heart and Brain
The results from this study offer a better understanding of brain organization and its intricate relationship with cognitive performance. The team said they plan to continue examining the effects of tea and its bioactive compounds on cognitive decline.10
While this study demonstrated long-term effects, a different one11 found evidence of short-term benefits linking consumption of black tea after fasting overnight with improved executive functioning, simple reaction time and reduced errors in cognitive tasks.
A key property found in green tea is epigallocatechin-3 gallate (EGCG), a type of catechin or flavonoid that works with antioxidants in the brain to improve cognition.12 In a clinical study to test how this works, 12 elderly nursing home residents with diagnosed cognitive dysfunction took 2 grams of green tea powder each day for three months. At the conclusion of the study, data demonstrated they had significantly improved scores on cognitive function tests.13
EGCG has also been shown14 to improve learning and reduce memory loss in subjects who consume a high-fat, high fructose diet (HFFD). In this study, EGCG also appeared to significantly modulate insulin resistance, which is another factor associated with cognitive decline.
Another study showed drinking green tea is associated with a lower risk of cognitive impairment,15 and a literature review of in vitro and in vivo administration of EGCG in participants suffering from Alzheimer’s disease found a reduction in beta-amyloid accumulation.16
Catechins Are a Strong Key to Good Health
The ability to break up beta-amyloid plaques may also be the basis for an association with EGCG and reduction of atherosclerotic plaques.17 The researchers believe the results demonstrate EGCG may be effective against the types of plaques that cause heart attack and stroke.18
In an extensive review of the literature,19 one team found epidemiological data and results from clinical and experimental studies demonstrating the benefit EGCG has on cardiovascular health. These benefits include reducing vascular inflammation, thrombogenesis, and oxidation, as well as modulating lipid profiles and inhibiting lipid peroxidation.
In addition to brain health and heart health, EGCG is an effective chemopreventive. One review of the literature found delayed cancer onset, prevention of colorectal adenoma and inhibition of melanoma metastasis in an animal model.20 Another found EGCG may synergistically inhibit cancer both in vitro and in vivo.21
Health Benefits and Warnings — Green Tea Extract
If drinking green tea is not something you enjoy and yet you still want the benefits, it may be worth your effort to investigate green tea extract. As defined by the National Cancer Institute,22 this is a polyphenol mixture isolated from the Camellia sinensis plant from which green tea is derived. It contains flavonoids, vitamins, and polyphenols, including EGCG.
As with any chemical you put into your body, there may be side effects. According to the University of Rochester Medical Center, green tea extract’s side effects may include anxiety, tremors, irritability and sleep problems related to the amount of caffeine.23
There have also been reports of liver damage with green tea extract when you consume higher amounts of EGCG in supplement form than you would get from simply drinking your tea.
Health Canada24 strengthened their warnings on green tea extract products, as did the Norwegian food safety authority and European Food Safety Authority25 after reviewing earlier papers26 linking dozens of cases of liver damage to the consumption of high amounts of EGCG. That said, supplementation with green tea extract in concentrations no greater than you would get from drinking green tea has several possible advantages, including:
- Help with heart, liver and brain health and support for blood pressure, bone mineral density and weight control27
- Reduction of oxidative stress28
- Support for exercise recovery and enhancement of antioxidant protection and exercise performance29
- Reduction of inflammation from nonalcoholic fatty liver disease30
- Enhancement of insulin sensitivity and help in regulating blood sugar production31
Different Teas and How They Taste
According to TeaClass.com, all tea leaves come from the Camellia senensis plant, and they’re categorized in five types, all distinguished by how they’re processed and oxidized or fermented:32
- Black
- Oolong
- Green
- White
- Pu’erh
Black tea is fully oxidized while oolong teas are partially oxidized. Green and white teas are not oxidized after the leaf harvesting. Pu’erh is a fermented, aged tea compressed into cakes.
When preparing them according to Chinese custom, each of the different teas is prepared in different vessels. For instance, oolong is traditionally brewed in a clay pot while green tea is prepared in a glass pot. In addition, the traditional ceremony involves an entire set of utensils including scoops, tray, decanter, fragrance cup, and tea cup.33
One cup of black tea contains approximately 25 to 48 mg of caffeine depending on the type and how it’s brewed, as opposed to a typical 8-ounce cup of brewed, black coffee, which contains 95 to 165 mg of caffeine.34
White tea is the least processed of all teas, with a delicate taste and natural sweetness. When this tea is brewed at a low temperature and short steeping time, you'll enjoy low amounts of caffeine than when hotter temperatures are used.35 All white teas are produced in China and only young, tender leaves are used.36
Green tea leaves are harvested in the morning and bypass oxidation, allowing the tea to retain much of the natural color, tannins, chlorophyll, and minerals.37 Oxidation is stopped by rapidly heating the leaves. When it’s brewed at lower temperatures it has less caffeine.38 Most are light green in color. The finely powdered matcha tea has a more vibrant green hue with “a grassy flavor and sweet aftertaste.”39
According to The Tea Spot, oolong teas have body and complexity compared to black tea, but a greater freshness of green tea related to the oxidation level.40 Oolong isn’t as robust as a black tea, but the fragrance and taste have been compared to fresh flowers or fresh fruit, TeaSource says41 Oolong is a deep amber or light green color with a smooth finish and malty flavor, according to Cup and Leaf.42
Black tea is fully oxidized,43 during which water is evaporated from the leaf, allowing the plant to absorb oxygen, resulting in a dark brown or black color and a more robust flavor.44
How to Store Your Tea
You'll want to take care as you store, brew and drink your tea to enjoy the greatest health benefits and best flavor. Like most fresh foods, good storage extends the shelf life, quality, and flavor.45 Light and UV rays will degrade your tea quickly, so avoid purchasing from vendors who store their product in clear containers.
Heat and moisture will degrade your tea and reduce shelf life. Interestingly, your tea will also absorb odor easily so avoid storing it near your spice cabinet or anywhere else there is a source of strong odors.46 Your tea should be sealed in an airtight container.
Additionally, you should keep your delicately flavored tea separate from your strongly scented teas. Using an opaque, nonreactive container — preferably glass or ceramic — with a double lid and tight seal will help to protect the shelf life of your product.47
Brew the Perfect Pot
In this short video, a representative from Ahmad Tea demonstrates one way to brew loose leaf tea. While he recommends brewing for five minutes, shorter times will produce a lighter flavor with less caffeine. Always use clean filtered water and fresh tea leaves.
Start with the instructions that come with your loose tea leaves, but don’t be afraid to experiment with the process you’re using until you find one you enjoy the most. Warming the brewing teapot is a must as it helps keep the water at a steadier temperature as the tea is brewing.
