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10 Evidence-Based Benefits of Green Tea

Health + Wellness
10 Evidence-Based Benefits of Green Tea
Green tea is touted to be one of the healthiest beverages on the planet. Solstizia / iStock / Getty Images Plus

By Kris Gunnars

Green tea is touted to be one of the healthiest beverages on the planet.


It's loaded with antioxidants that have many health benefits, which may include:

There may be even more potential health benefits.

This article looks at the evidence behind 10 possible health benefits of green tea.

1. Green Tea Contains Healthy Bioactive Compounds

Green tea is more than just a hydrating beverage.

The green tea plant contains a range of healthy compounds that make it into the final drink.

Tea is rich in polyphenols, which are natural compounds that have health benefits, such as reducing inflammation and helping to fight cancer.

Green tea contains a catechin called EGCG (epigallocatechin-3-gallate). Catechins are natural antioxidants that help prevent cell damage and provide other benefits.

These substances can reduce the formation of free radicals in the body, protecting cells and molecules from damage. These free radicals play a role in aging and many types of diseases.

EGCG is one of the most powerful compounds in green tea. Research has tested its ability to help treat various diseases. It appears to be one of the main compounds that gives green tea its medicinal properties.

Green tea also has small amounts of minerals that can benefit your health.

Try to choose a higher quality brand of green tea, because some of the lower quality brands can contain excessive amounts of fluoride.

That being said, even if you choose a lower quality brand, the benefits still outweigh any risk.

Summary

Green tea is loaded with polyphenol antioxidants, including a catechin called EGCG. These antioxidants can have various beneficial effects on health.

2. Green Tea Can Improve Brain Function

Green tea does more than just keep you alert, it might also help boost brain function.

The key active ingredient is caffeine, which is a known stimulant.

It doesn't contain as much as coffee, but enough to produce a response without causing the "jittery" effects associated with taking in too much caffeine.

Caffeine affects the brain by blocking an inhibitory neurotransmitter called adenosine. This way, it actually increases the firing of neurons and the concentration of neurotransmitters like dopamine and norepinephrine.

Research has consistently shown that caffeine can improve various aspects of brain function, including mood, vigilance, reaction time, and memory.

However, caffeine isn't the only brain-boosting compound in green tea. It also contains amino acid L-theanine, which is able to cross the blood-brain barrier.

L-theanine increases the activity of the inhibitory neurotransmitter GABA, which has anti-anxiety effects. It also increases dopamine and the production of alpha waves in the brain.

Studies show that caffeine and L-theanine can have synergistic effects. This means that the combination of the two can have particularly powerful effects in improving brain function.

Because of the L-theanine and the small dose of caffeine, green tea might give you a much milder and different kind of "buzz" than coffee.

Many people report having more stable energy and being much more productive when they drink green tea compared to coffee.

Summary

Green tea contains less caffeine than coffee, but enough to produce an effect. It also contains the amino acid L-theanine, which can work synergistically with caffeine to improve brain function.

3. Green Tea Increases Fat Burning

If you look at the ingredients list for any fat burning supplement, chances are, green tea will be on there.

This is because, according to research, green tea can increase fat burning and boost metabolic rate.

In one study involving 10 healthy men, taking green tea extract increased energy expenditure by 4%. In another involving 12 healthy men, green tea extract increased fat oxidation by 17% compared to those taking a placebo.

However, some studies on green tea don't show any increase in metabolism, so the effects may depend on the individual and how the study was set up.

Caffeine may also improve physical performance by mobilizing fatty acids from fat tissue and making them available for use as energy.

Two separate review studies reported that caffeine may increase physical performance by approximately 11–12%.

Summary

Green tea may boost metabolic rate and increase fat burning in the short term, although not all studies agree.

4. Green Tea Antioxidants May Lower the Risk of Some Cancers

Cancer is caused by uncontrolled growth of cells. It's one of the world's leading causes of death.

Research has shown that oxidative damage can lead to chronic inflammation, which can lead to chronic diseases, including cancers. Antioxidants can help protect against oxidative damage.

Green tea is an excellent source of powerful antioxidants.

Research has linked green tea compounds with a reduced risk of cancer, including the following studies:

  • Breast cancer: A comprehensive review of observational studies found that women who drank the most green tea had an approximately 20–30% lower risk of developing breast cancer, one of the most common cancers in females.
  • Prostate cancer: One study found that men drinking green tea had a lower risk of advanced prostate cancer.
  • Colorectal cancer: An analysis of 29 studies showed that those drinking green tea were around 42% less likely to develop colorectal cancer.

Many observational studies have shown that green tea drinkers are less likely to develop several types of cancer, but more high-quality research is needed to confirm these effects.

To get the most health benefits, avoid adding milk to your tea. Some studies suggest it can reduce the antioxidant value in some teas.

Summary

Green tea has powerful antioxidants that may protect against cancer. Multiple studies show that green tea drinkers have a lower risk for various types of cancer.

5. Green Tea May Protect the Brain From Aging

Not only can green tea improve brain function in the short term, it may also protect your brain as you age.

Alzheimer's disease is a common neurodegenerative disease and the most common cause of dementia in older adults.

Parkinson's disease is another common neurodegenerative disease and involves the death of dopamine-producing neurons in the brain.

Several studies show that the catechin compounds in green tea can have various protective effects on neurons in test tubes and animal models, possibly lowering the risk for dementia.

Summary

Bioactive compounds in green tea can have various protective effects on the brain. They may reduce the risk of dementia, a common neurodegenerative disorder in older adults.

6. Green Tea Can Reduce Bad Breath

The catechins in green tea also have benefits for oral health.

Test tube studies suggest that catechins can suppress the growth of bacteria, potentially lowering the risk for infections.

Streptococcus mutans is a common bacterium in the mouth. It causes plaque formation and is a leading contributor to cavities and tooth decay.

Studies indicate that the catechins in green tea can inhibit the growth of oral bacteria in the lab, but no evidence shows that drinking green tea has similar effects.

However, there's some evidence that green tea can reduce bad breath.

Summary

The catechins in green tea may inhibit the growth of bacteria in the mouth, reducing the risk for bad breath.

7. Green Tea May Help Prevent Type 2 Diabetes

The rates of type 2 diabetes are increasing in recent decades. The condition now affects about 1 in 10 Americans.

Type 2 diabetes involves having elevated blood sugar levels, which may be caused by insulin resistance or an inability to produce insulin.

Studies show that green tea can improve insulin sensitivity and reduce blood sugar levels.

One study in Japanese individuals found that those who drank the most green tea had an approximately 42% lower risk of developing type 2 diabetes.

According to a review of 7 studies with a total of 286,701 individuals, tea drinkers had an 18% lower risk of developing diabetes.

Summary

Controlled trials show that green tea can cause mild reductions in blood sugar levels. It may also lower the risk of developing type 2 diabetes.

8. Green Tea May Help Prevent Cardiovascular Disease

Cardiovascular diseases, including heart disease and stroke, are the leading causes of death worldwide.

Studies show that green tea can improve some of the main risk factors for these diseases, which includes improving total cholesterol and LDL (bad) cholesterol levels.

Green tea also increases the antioxidant capacity of the blood, which protects the LDL particles from oxidation, which is one part of the pathway toward heart disease.

Given the beneficial effects on risk factors, it may not be surprising that people who drink green tea have up to a 31% lower risk of dying from a cardiovascular disease.

Summary

Green tea may lower total and LDL cholesterol, as well as protect the LDL particles from oxidation. Studies show that people who drink green tea have a lower risk of cardiovascular disease.

9. Green Tea May Help You Lose Weight

Given that green tea can boost the metabolic rate in the short term, it makes sense that it could help you lose weight.

Several studies show that green tea can help reduce body fat, especially in the abdominal area.

One of these studies was a 12-week randomized controlled trial involving 240 people with obesity.

In this study, those in the green tea group had significant decreases in body fat percentage, body weight, waist circumference, and belly fat compared with those in the control group.

However, some studies don't show a statistically significant increase in weight loss with green tea, so researchers need to perform further studies to confirm this effect.

Summary

Some studies show that green tea leads to increased weight loss. It may be particularly effective at reducing the dangerous abdominal fat.

10. Green Tea May Help You Live Longer

Given that some compounds in green tea may help protect against cancer and heart disease, it makes sense that it could help you live longer.

In one study, researchers studied 40,530 Japanese adults over 11 years. Those who drank the most green tea — 5 or more cups per day — were significantly less likely to die during the study period:

  • Death of all causes: 23% lower in women, 12% lower in men.
  • Death from heart disease: 31% lower in women, 22% lower in men.
  • Death from stroke: 42% lower in women, 35% lower in men.

Another study involving 14,001 older Japanese individuals found that those who drank the most green tea were 76% less likely to die during the 6-year study period.

Summary

Studies show that people who drink green tea may live longer than those who don't.

11. The Bottom Line

Green tea has a range of possible health benefits.

To help you feel better, lose weight, and lower your risk for chronic diseases, you might want to consider making green tea a regular part of your life.

If you'd like to try it, there's a wide variety of green tea products available online.

Reposted with permission from Healthline.

For detailed source information, see original story at Healthline.

A net-casting ogre-faced spider. CBG Photography Group, Centre for Biodiversity Genomics / CC BY-SA 3.0

Just in time for Halloween, scientists at Cornell University have published some frightening research, especially if you're an insect!

The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.

"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."

The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.

They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.

They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.

But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.

"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.

What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.

It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.

To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.

First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.

Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.

University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.

"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."

Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.

Hoy agreed.

"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.

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