What is Green Tea?
Green tea is a type of tea that is made from Camellia sinensis leaves that have not undergone the same withering and oxidation process used to make oolong teas and black teas. Green tea originated in China, but its production and manufacture has spread to many other countries in Asia.
Several varieties of green tea exist, which differ substantially based on the variety of C. sinensis used, growing conditions, horticultural methods, production processing, and time of harvest.
It is one of the healthiest beverage as it is loaded with antioxidants and nutrients that are beneficial to body health in general. Some of its health benefits includes aids in weight loss, cures hangover, brain health, skin care among others.
History of Green Tea
If one were to study green tea in any detail, rather than finding a concise history of discovery and a subsequent spread across the continents, green tea’s history is much more convoluted and many different versions and legends abound regarding the discovery of tea.
What can be verified, however, is that tea was discovered in its greenest form over five thousand years ago. Some versions of history have a flower falling into a tea cup while another has a man eating a leaf and realizing how delicious it would be steeped in water. Regardless of the facts (or legends) tea was discovered in some way and went on to change the world.
For centuries, all tea was green tea. Green tea is simply the leaves of the camellia sinensis plant placed to steep in hot water. The leaves had not undergone any of the oxidation process of tea leaves today, so it was tea in its most natural form. This version of green tea is still enjoyed around the world today as are many other versions of the same tea leaf.
In about 600 AD, the most important book regarding tea was written in China. Lu Yu was the author of Cha Jing, or Tea Classic. The book is an important document both for historical purposes and as an insight into the lives of a country which introduced tea to the world. The book detailed exactly how a cup of green tea should be made and how it should be served. Outside of the interesting attention to detail, the book made it clear that tea is one of the oldest documented beverages we still enjoy today in almost its exact same form.
Over the centuries, different forms of green tea were introduced as they were discovered. Oolong and black tea were created much later than the country’s fascination with green tea was developed – black tea is a fermented version of green tea and Oolong is semi fermented. These two different tea versions are thought to have occurred in the 1600s, almost 5,000 years after the discovery of green tea and 800 years after green tea began its journey through Asia, beginning with Japan.
The Japanese contributed much to green tea by offering different variations on the tea leaves that are still enjoyed today. The Japanese also offered much formality to tea and integrated the drink into their culture in a very large way, particularly through the tea ceremonies. In countries such as Japan and China, tea and its presentation have become an art form.
Throughout the next centuries, tea spread throughout the globe and became a much sought after commodity, although green tea was not as popular in the western world as black teas for many centuries. Today the western world is still in the process of discovering the delicious variations of green tea and other tea types as they delve into the secrets and customs of the Eastern world – the land that created the sensation.
Types of Green Tea
There are a wide variety of green teas available around the world. The type called sencha is the most popular and usually the easiest to find. Other lesser known varieties of green tea include:
- Fukamushi Sencha (or Fukamushi Ryokucha)
What is matcha green tea?
Matcha green tea is a high-grade, finely ground, concentrated green tea. It’s been traditionally used in Japanese tea ceremonies for hundreds of years and has recently gained notoriety for its high antioxidant content. When you drink matcha tea, you drink the actual tea leaves, which have been ground up. This allows you to obtain even more nutrients compared to drinking steeped green tea.
Tea plants that are specifically grown and used to make matcha are also typically shaded for two weeks to increase chlorophyll levels before the leaves are picked, further boosting concentration of healthy compounds. Matcha green tea tends to be more expensive than buying tea leaves for steeping, but a little goes a long way. Matcha is usually available in powder form and is a good choice for adding green tea’s taste and the benefits of green tea to recipes like smoothies, baked goods or ice cream.
Green Tea Nutrition
The nutritional value of green tea and highly debated, but many experts agreed that the nutritional benefits of green tea is really incredible. Here is some interesting nutritional information about this tea:
- Green tea is a hydrating calorie-free beverage whose consumption is recommended up to eight cups per day.
- A cup of this tea is 99.5% water. Tea is second only to water as an ideal beverage choice for body hydration.
- So don’t forget that a key ingredient of tea is water; the better the water, the better the tea.
- Green tea is an exceptionally good source of antioxidants and alkaloids.
- It is believed that there are no calories in green tea without any additives or sweeteners. But all teas and coffees contain some calories – but very few.
- Green tea contains various vitamins like A, D, E, C, B, B5, H and K.
- It is a rich source of Manganese and has many other beneficial minerals as Zinc, Chromium and Selenium.
- The most important active component in green tea epigallocatechin-3-gallate (EGCG) is many times a more powerful antioxidant than vitamin C or vitamin E.
- It contains caffeine, but the caffeine content of green tea is very low compared to other sources of caffeine.
Green tea contains flavonols and catechins.The catechins in green tea are:
- gallate derivatives
Green tea also contains
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- Epigallocatechin-3-gallate (EGCG)
- linoleic acid
- methylxanthines (caffeine, theopylline, and theobromine)
- trace amounts of minerals like magnesium, calcium, manganese, iron, chromium, copper, and zinc
- trace amounts of carotenoids
- lactones and hydrocarbons, esters, and aldehydes (all of which are volatile compounds)
|Total Fat||0 g||Potassium||40 mg|
|Saturated||0 g||Total Carbs||1 g|
|Polyunsaturated||0 g||Dietary Fiber||0 g|
|Monounsaturated||0 g||Sugars||0 g|
|Trans||0 g||Protein||0 g|
Health Benefits of Green Tea
1. Heart Health
Green tea contains flavonoids, antioxidants that protect against heart disease by slowing the breakdown of Low Density Lipoprotein cholesterol, preventing blood clots, and improving blood vessel function.
2. Brain Health
Green Tea has the 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.
3. Aids in Weight Loss
Green tea increases fat burning and boost the metabolic rate. The polyphenol found in green tea works to intensify levels of fat oxidation and the rate at which your body turns food into calories.
4.Reduces Cancer risk
Green tea contains antioxidants that help reduce the risk of developing cancer
5. Prevents Arthritis
Green tea contains quercetin which is a powerful anti-inflammatory and antioxidant. Also tea’s polyphenols—antioxidant properties—are also anti-inflammatory and improve arthritis-related immune responses.
A study conducted at Case Western Reserve University, researchers gave mice the equivalent of four cups of green tea a day, then gave them a substance that would normally produce rheumatoid arthritis. The tea-drinking mice were far less likely to develop arthritis than mice that drank water.
6. Skin Care
The antimicrobial and antioxidant compounds found in green tea helps in clearing acne. To benefit, make a cup of green tea, let cool, and use as a face wash, or lay the tea bag directly on the skin to act as a compress for particularly bad pimples. For oily skin, mix peppermint tea with the green tea for an oil-blasting wash.
7. Helps manage diabetes
Green tea apparently helps regulate glucose levels slowing the rise of blood sugar after eating. This can prevent high insulin spikes and resulting fat storage.
8. May Help Prevent Alzheimer’s or Memory Loss
Green tea prevents the breakdown of acetylcholine, the neurotransmitter strongly linked with memory. The tea also inhibits enzymes known as BuChE and beta-secretase. These enzymes are found in protein deposits found in the brain of Alzheimer’s patients.
Japanese researchers published a study on green tea and its effect on the beta-amyloid protein plaques found in Alzheimer’s disease in the April 2008 issue of the Journal of Nutritional Biochemistry. The protein plaques associated with Alzheimer’s disease increase brain cell damage and death due to oxidative stress. The researchers found that green tea catechins reduced the level of damaging free radicals in the brains of rats. The green tea rodents showed much less plaque-induced deficits in memory compared to rodents that didn’t receive green tea and those that were infused with beta-amyloid proteins.
9. Boosts Immunity
Green tea contains catechins wich helps boost the immune function. The tea protects against oxidants and radicals, thereby enhancing immunity. The EGCG (epigallocatechin gallate) in green tea has the ability to increase the number of regulatory T cells – and these help improve immune function and suppress autoimmune diseases.
10 Aids in digestion
Green tea contains epigallocatechin gallate (EGCG) which improves colitis symptoms. Colitis is an inflammatory disorder that disturbs the digestive health. Green tea also offers vitamins B, C, and E – which are important for digestion.
11. Oral Health
Green tea reduces inflammation and limits the growth of certain bacteria that can lead to periodontal diseases. Green tea also prevents tooth decay by limiting the development of bacterial plaque. The polyphenols in green tea fight plaque by suppressing glucosyltransferase, a compound oral bacteria use to feed on sugar.
12. Helps cure hangover
Green tea is high in anti oxidants that help detoxify the liver and help relieve hangover symptoms.However, green tea was also found to cause liver toxicity in certain studies. Hence, consult your doctor before using green tea for this purpose.
13. Helps Treat Dark Circles And Puffy Eyes
Green tea contains tannins which help treat puffy eyes and dark circles. The caffeine in green tea reduces puffiness by shrinking the blood vessels in the area. And on dark circles, it works by decreasing the dilation of blood vessels under the eyes.
14. Help Prevent Diabetes or Insulin Resistance
Certain studies indicate that intake of flavan-3-ols and/or anthocyanidins found in green tea may improve glycemic control and help normalize blood sugar levels. Due to its anti-inflammatory properties, green tea is believed to be beneficial for those who are at-risk or diagnosed with type 2 diabetes. Green tea’s catechins, especially EGCG, appear to have anti-obesity and antidiabetic effects.
15. Promotes Bone Health
University of Hong Kong researchers published a study in the August, 2009 Journal of Agricultural and Food Chemistry concerning green tea and bone health. When the bone cells of rats were exposed to green tea catechins, EGC in particular stimulated an enzyme that promotes bone growth by 79 percent. The catechins also increased bone mineralization and weakened the activity of cells that reabsorb bone rather than form it.
16. Prevents Eye Disease and Protects Vision
One study that was published in the February 2010 issue of the Journal of Agricultural and Food Chemistry investigated the effects of catechins on eye diseases and found that consuming more catechins may help protect the eyes from oxidative damage and vision loss. Scientists involved in the study found evidence that catechins can pass from the digestive tract of rodents to the tissues of their eyes and reduce oxidative stress for up to 20 hours after ingestion.
17. May Reduce Your Appetite
Does green tea really burn fat, and will drinking green tea help you lose more weight? According to some research findings, consuming antioxidants found in green tea, especially catechins and the compound called EGCG, may promote metabolic health and modestly prevent weight gain. When 11 studies and articles were included in one 2009 meta-analysis that was published in the International Journal of Obesity, researchers found that “catechins or an epigallocatechin gallate (EGCG)-caffeine mixture have a small positive effect on weight loss and weight maintenance.” (12)
Overall, EGCG’s effects remain somewhat controversial; some studies have found only modest effects on metabolism, while others have found that consuming more EGCG alone without other lifestyle changes does not do anything significant to improve body weight.
18. Green Tea Increases Fat Burning and Improves Physical Performance
If you look at the ingredients list for any fat burning supplement, chances are that green tea will be on there. This is because green tea has been shown to increase fat burning and boost the metabolic rate, in human controlled trials. In one study in 10 healthy men, green tea increased energy expenditure by 4%. Another study showed that fat oxidation was increased by 17%, indicating that green tea may selectively increase the burning of fat. However, some studies on green tea don’t show any increase in metabolism, so the effects may depend on the individual.
Caffeine itself has also been shown to improve physical performance by mobilizing fatty acids from the fat tissues and making them available for use as energy. In two separate review studies, caffeine has been shown to increase physical performance by 11-12%, on average.
19. Green Tea Can Kill Bacteria, Which Improves Dental Health and Lowers Your Risk of Infection
The catechins in green tea also have other biological effects. Some studies show that they can kill bacteria and inhibit viruses like the influenza virus, potentially lowering your risk of infections. Streptococcus mutans is the primary harmful bacteria in the mouth. It causes plaque formation and is a leading contributor to cavities and tooth decay. Studies show that the catechins in green tea can inhibit the growth of Streptococcus mutans. Green tea consumption is associated with improved dental health and a lower risk of caries. Multiple studies also show that green tea can reduce bad breath.
20. Reduce Your Risk of Cardiovascular Disease
Cardiovascular diseases, including heart disease and stroke, are the biggest causes of death in the world. Studies show that green tea can improve some of the main risk factors for these diseases. This includes total cholesterol, LDL cholesterol and triglycerides.
Green tea also dramatically increases the antioxidant capacity of the blood, which protects the LDL particles from oxidation, which is one part of the pathway towards heart disease. Given the beneficial effects on risk factors, it is not surprising to see that green tea drinkers have up to a 31% lower risk of cardiovascular disease
How Can You Make Green Tea At Home?
Very simple. Take green tea leaves and place them in a tea strainer. Now, place the strainer over an empty cup. Pour hot water over the tea leaves. Steep the tea leaves for about 2 to 3 minutes (but not longer as your tea might get slightly bitter). Allow it to cool down and then enjoy your perfect cup of tea.
You can also prepare green tea ice cream. You need 1 cup of heavy cream, 1/4 cup of sweetened condensed milk, and 4 1/2 teaspoons of green tea powder. Just mix the green tea powder with 3 tablespoons of hot water and let it cool. Whip the heavy cream until it is stiff. Mix the green tea mixture with 1/4 cup of sweet condensed milk. Add green tea to this mixture and mix well. Transfer this to a baking pan and cover with a plastic wrap. Freeze for at least 6 hours.
Using green tea is quite simple. The easiest way is to drink the tea. You can mix green tea leaves with other beneficial ingredients like honey or turmeric to prepare potent face masks or face packs – you can also use these to enhance hair health.
Negative Effects Of Green Tea
Are there any side effects of green tea? You might be wondering why green tea is bad for you, well check out for yourself here. Mentioned here are some of the surprising green tea health risks.
1. Stomach Problems
Caffeine could be the most common culprit. Though it has a lower amount of caffeine than other types of tea, it still can cause problems. This is because caffeine increases the amount of acid involved in the digestive process. This can cause pain or nausea. Also, though green tea has been touted to prevent cancer, especially gastric cancer, studies say that there is insufficient information in this regard. As per a report published by the University of Rochester Medical Center, if you experience stomach pain after drinking green tea, visit your doctor right away.
2. Iron Deficiency And Anemia
As per a Taiwanese study, consuming too much of green tea could lead to iron deficiency anemia. More importantly, taking green tea after an iron-rich meal can make the main compounds in the tea bind to the iron. If this happens, the green tea will lose its potential as an antioxidant.
EGCG is the main compound in green tea. This compound is known to inhibit an enzyme called myeloperoxidase, which might cause inflammation. But when the tea is consumed along with iron-rich foods, EGCG loses its ability to inhibit the inflammatory action of myeloperoxidase, thereby leading to inflammation. In other words, it’s not just what you eat, but also what you eat it with, which determines the benefits.
Green tea contains tannins that block the absorption of iron from food and food supplements. Certain sources say that adding lemon to green tea or drinking it in between meals can counter this issue. Further research adds that consuming tea can decrease the absorption of iron from plant-based sources (as much as by 64%). For mitigating the effect, one can drink tea at least one hour before or after meals; and also include more foods rich in vitamin C (as vitamin C aids in iron absorption).
Another Taiwanese study has also linked excessive tea consumption (green tea, in particular) to decreased iron absorption and resultant anemia. And according to a report by the PennState University, the polyphenol antioxidants in green tea can inhibit iron absorption. This happens when the polyphenols bind to the iron in the intestinal cells and prevent it from entering the bloodstream. This polyphenol-iron complex is eventually excreted from the body.
Again, because of the caffeine, green tea might cause mild to severe headaches. And headaches can also be caused by iron deficiency, which, as we have seen already, could occur through an excessive intake of green tea.
Apart from headaches, green tea can also cause dizziness. And as per studies, the maximum tolerated dose of green tea in humans is 9.9 grams per day – which is roughly equivalent to 24 cups of the beverage in a day. One important point to note is that though the green tea extract is listed in over 100 over-the-counter herbal supplements and preparations, its use as a treatment for any ailment is not strictly regulated by the FDA. Also, the safety of the long-term use of green tea extracts is not clearly defined. Green tea can make one feel jittery and shaky, which may not be the case with decaffeinated green tea products.
4. Might Cause Insomnia
Another possible bad effect of green tea is a problem with sleeping. This can be averted by limiting green tea consumption, as the fatal dose of the caffeine in green tea is estimated to be 10 – 14 grams in a day.
Taking green tea too late in the day can also cause this effect. One very obvious reason for this is the caffeine, which stimulates the nervous system and can interfere with one’s sleep. More importantly, pregnant and lactating women must limit their green tea intake as it may pass into breast milk and cause insomnia in nursing infants. A report by the Southern Illinois University states that green tea can cause numerous other sleep disorders as well if taken in excess.
5. Irregular Heartbeat
It’s caffeine, again. Caffeine is known to stimulate the heart as well. It causes your heart rate to speed up, causing irregularly fast heartbeat – a condition called tachycardia. This condition can make you feel as if your heart is pounding in your chest. You are more aware of your heartbeat than usual. Also called palpitations, this condition could even result in chest pain or angina (any other intense localized pain). A change in your normal heart rate could pose a serious threat.
According to another report by the Health University of Utah, intaking of a green tea capsule must be reconsidered in case you are suffering from heart disease or an irregular heartbeat.
As per one Indian study, green tea polyphenols can, in fact, cause oxidative stress. And excessive intake of caffeine, including that from green tea, can trigger nausea and vomiting. Moderate amounts of caffeine are noted to be 300 to 400 mg per day. If the amount exceeds, it can result in certain side effects, including vomiting.
Diarrhea could occur if you are new to green tea. Loose stools could be one of the mild side effects (due to the caffeine content), which can eventually subside as you get used to the beverage. Diarrhea can also happen with excessive intake of green tea. One way to stop this is to reduce the consumption. Another way is to ensure you don’t drink green tea on an empty stomach. Instead, you can have the tea along with a full meal. This is because having food in your stomach can potentially reduce the ill effects of caffeine, diarrhea included.
You can also try taking green tea later in the day, most preferably in the afternoon. This is less likely to cause the side effect as the digestive effects in the afternoon and beyond are not as pronounced as in the morning. In the case of severe diarrhea, stop green tea intake and consult your doctor right away. Mild diarrhea might be common. But a severe case is not. Also, ask your health care provider to rule out the possibilities of irritable bowel disease or inflammatory bowel syndrome.
According to the US National Library of Medicine, green tea is one of the many herbs that contain caffeine. And this is the primary reason it can trigger diarrhea. In addition to diarrhea, green tea can also cause stomach gas. Caffeine has also found to stimulate the muscles in the digestive tract. This can cause issues in people with a sensitive colon. Which is why, if you have any history of colon problems, you must take expert advice before consuming green tea.
8. Muscle Tremors And Contractions
Excessive caffeine consumption has also been linked to muscle spasms and twitching. And individuals with an abnormal sinus rhythm must limit caffeine intake. Caffeine has also been linked to restless leg syndrome. If you are an individual with mild to moderate severity of this condition, it’s better you check your green tea (or caffeine) intake. One common characteristic of restless leg syndrome is the symptoms occurring when the individual is inactive. This could happen in the night while going to bed, or an aggravated pain in the evening, or twitching of the legs in the nighttime. Caffeine could aggravate any of these symptoms, including muscle spasms. 240 ml of green tea contains about 25 mg of caffeine, and according to one report, this caffeine can also cause tremors.
Green tea is acidic, and hence can irritate the esophageal lining, causing acid reflux or heartburn. The condition could get worse if an individual is already suffering from heartburn (or acid reflux). Though normal brewed green tea could not be so potent, the bottled green tea that you so often find in the markets could be the real threat. This is because most of the green teas that come in bottles are fortified with an acidic preservative like ascorbic acid. This preservative can loosen the lower esophageal sphincter, which otherwise keeps the stomach acid from rising up the esophagus.
Certain bottled green teas come with a citrus flavoring, making them all the more acidic. And in case you prefer to go for green tea capsules, discuss with your doctor once. Because the green tea extract in the capsules might also trigger heartburn symptoms. Also, only buy high-quality tablets at a proper health food store. According to a Japanese study, green tea consumption has been linked to GERD, or gastroesophageal reflux disease. The caffeine in green tea was also found to increase stomach acid, which can lead to gastritis.
It has been found that long-term caffeine dosages of above 1.5 grams per day can lead to certain non-specific symptoms, a couple of them including vertigo and dizziness.
11. Tinnitus (Ringing In The Ears)
According to the American Tinnitus Association, beverages that contain caffeine are known to aggravate tinnitus. Green tea, being a source of caffeine, can lead to the condition.
According to one study, green tea extract was found to significantly accelerate the onset of convulsions in the mice that were tested upon. The tea had always increased the duration of the convulsions. Also, green tea might keep folic acid from working the way it must. This can lead to a condition quite similar to folic acid deficiency. Excess folic acid has been linked to seizures. Though this might seem that green tea, in a way, might help combat seizures – there is no evidence that it actually does. Further research also suggests that high doses of green tea can lead to convulsions.
13. Bleeding Disorders
Caffeine in green tea can increase the risk of bleeding. Which is why you must stay away from it if you have any bleeding disorder. According to the University of Maryland Medical Center, green tea, when mixed with aspirin, might prevent the blood from clotting. Using the two at a time can increase your risk of bleeding.
Though there are studies that have highlighted the benefits of green tea for diabetes, there are studies that state otherwise too. A small number of studies using green tea, the extract, and catechins (the main ingredient in green tea) only showed disappointing results in treating Type 2 diabetes. The same results occurred when it came to protecting healthy individuals from the disease.
Black tea contains caffeine. And so does green tea. But when one uses the two together, the risk of caffeine side effects just multiplies. Drinking the tea drastically increases the pressure in the eye. This occurs within 30 minutes of drinking the tea and lasts as long as 90 minutes. Further research completely discourages women with glaucoma from taking green tea or its extract.
16. High Blood Pressure
The flavonoids in green tea that are touted to be healthy (which they are) are absorbed by the body at a rapid rate. This, along with the caffeine content in the tea, might lead to a sudden (but temporary) rise in blood pressure levels. Numerous studies have found green tea to elevate blood pressure levels. Though the rise in the levels doesn’t raise any health concerns, one thing is clear – green tea may not be the safest or the most dependable way to regulate blood pressure levels.
As per another Chinese study, a higher dose of green tea contains more caffeine, which invariably causes increased blood pressure. And an Australian study offers a different viewpoint. The study was conducted to test if green tea could reduce the blood pressure effects of caffeine. The findings suggested that the tea ingestion caused higher increases in blood pressure than caffeine alone.
According to another study, green tea might lessen the beneficial effects of nadolol, a medication used to treat high blood pressure. What we understand from the results is that patients on blood pressure medication, especially the ones taking nadolol, must avoid green tea consumption. Green tea was found to interfere with the absorption of the medication (and similar medications, potentially) in the intestine.
Caffeine can cause a short but dramatic increase in your blood pressure levels. Experts believe this happens because caffeine blocks a hormone that otherwise keeps your arteries widened. It is also believed that caffeine provokes your adrenaline glands to produce more adrenaline, thereby raising blood pressure levels.
It also has been found that individuals who consume caffeine regularly have a higher average blood pressure than those who drink none. This effect of caffeine is the strongest amongst overweight men or those over 70 years of age.
One good way to check if the caffeine in your green tea is elevating your blood pressure levels is to measure your blood pressure readings 30 to 120 minutes after you have taken the beverage. If your readings increase by 5 to 10 points, you are sensitive to caffeine. And this means, you need to cut back on green tea and other forms of caffeine. But wait, ensure you cut back on caffeine gradually over a period of a few days, just to avoid withdrawal symptoms such as a headache.
17. Liver Disease
Nowadays, green tea extracts are vigorously marketed as weight loss supplements. Though there is little evidence supporting the efficacy of green tea in this aspect, certain serious side effects, including acute liver failure, are being reported. As per a New York study, green tea extract is one of the many herbal and dietary supplements associated with liver abrasion.
The catechins in green tea deliver huge benefits like lowered cholesterol and reduced risk of cancer and cardiovascular disease. But if taken in high doses, especially similar to the dosage in weight loss supplements, these catechins cause liver toxicity.
Green tea supplements contain huge amounts of polyphenols, the most well known of them being EGCG (also called epigallocatechin gallate). As per certain case reports, consumption of 700 to 2,000 mg of EGCG per day led to serious liver issues. Hence, if you are at a risk of developing any type of liver disease, limit your green tea intake. And ditch the supplements. Totally.
Another New York study has focused on a case of acute liver failure in an individual following the intake of a weight loss product containing green tea extract. In one such weight loss herbal product that was linked to acute liver injury, green tea extract was found to be one of the primary ingredients.
Though there are a few studies that speak about the protective effect green tea can have on the liver, it is but a fact that only large-scale randomized trails can give the properly validated conclusions.The United States National Library of Medicine speaks of certain other weight loss products containing green tea extracts, which were eventually linked to liver issues.
According to another Canadian study, there is an increasing body of literature supporting what could be serious side effects (liver toxicity, in particular) caused by green tea extract supplements.
Caffeine has been found to inhibit calcium absorption. It can also increase the rate of calcium excretion in the body. This results in a leaching effect on calcium levels in the bones, although only temporarily. But with extended consumption, this could lead to bone diseases like osteoporosis.
As per one study by the University of Connecticut, consumption of green tea extract resulted in lower femur length. It also led to lower volume, mineral content, cortical volume and thickness of the bone. This suggests that consumption of large quantities of green tea can lead to a reduced rate of bone accumulation during the formative years of an individual. An excessively high dosage of green tea can also become a source of prooxidants, negatively impacting the bone matrix.
19. Skin Allergies
The commonest allergies associated with green tea consumption are eczema and hives. An individual can also experience a tingling sensation on the face, lips, tongue, or in the throat.
Although rare, one severe allergic reaction green tea can cause is an anaphylactic shock. This is when the throat swells, blood pressure levels suddenly drop, hives break out, the abdomen might start to ache, and the individual might experience dizziness and anxiety.
20. Kidney Issues
A review of studies has proven that the very polyphenols that are credited with preventing cancer and heart disease can also cause kidney damage if taken in excessive quantities. As per experts, people consuming green tea supplements must exercise caution, in particular.
21. Issues With The Thyroid Gland
Studies have suggested that the catechins in green tea might affect the functioning of the thyroid gland. As per one study published in 2013, catechins can disrupt thyroid function and block the production of hormones. This can also lead to the enlargement of the thyroid glands. Hence, if you already are on thyroid medication, take your doctor’s advice on green tea intake.
Tea consumption, in general, has also been linked to reduced production of T3 and T4 hormones. This leads to an increased production of TSH (thyroid stimulating hormone), which can cause thyroid issues. One Indian study states that thyroid function could be impaired by high doses of green tea extracts. Another Japanese study had established a link between high green tea intake and premenopausal thyroid cancer risk. Though this wasn’t the case with postmenopausal cancer risk, caution is advised.
22. Frequent Urination
The caffeine in green tea also acts as a natural diuretic. As per reports, keeping green tea intake within 5 cups per day (or 200 to 300 mg of caffeine per day) can be one solution. Green tea is also one of those beverages that can aggravate the bladder. This is especially true if the individual is suffering from a urinary tract infection. In such an eventuality, they must avoid green tea (or any form of caffeine) and drink plenty of water instead.
The caffeine in green tea can also cause bladder spasms leading to bladder control issues. Caffeine can even constrict the smooth muscles of the bladder, making urination difficult. One alternative could be intake of decaffeinated green tea. But hey, consult your doctor first. In fact, frequent urination is one of the symptoms of caffeine sensitivity one must watch out for.In certain sensitive women, tea might even cause bladder irritation and make them leak urine. In fact, avoiding tea or coffee or any caffeinated beverage (including green tea) is one way to help treat urinary tract infection.
One study states that consuming green tea too often can lower fertility. In the study, embryos and larvae subjected to smaller doses of green tea were slower to develop. They also showed a decline in their ability to produce offspring. In another study, the test group treated with green tea leaf extract showed a decrease in the serum testosterone levels. Green tea was also found to impair development and reproduction in fruit flies. And similar results are potentially possible in humans as well.
One of the major bad effects of drinking green tea, or green tea in this context, with respect to teeth is it contains tannins. And two, it is its acidic nature. These two factors cause the tea to stain your teeth. Another downside is what we have seen with calcium – caffeine in green tea can slow down the absorption of calcium, weakening teeth or limiting their growth.
Negative Effects Of Green Tea In Pregnant Women
Since green tea contains caffeine, and since caffeine is a diuretic, it must be limited during pregnancy. The reason being caffeine might affect the amount of water in the body. Hydration, as we know, is crucial during pregnancy – and with diuretics like caffeine, there could be a problem. Losing too much of water could lead to an imbalance in the body’s electrolytes.
According to the American College of Obstetricians and Gynecologists, a woman must not consume more than 200 mg of caffeine a day during pregnancy. More importantly, caffeine is one of the many substances your baby cannot metabolize or use. Studies have stated that pregnant women who intake green tea increase the risk of birth defects like spina bifida. Also, as we had seen before, green tea could result in a folic acid deficiency. And there is no need to discuss the importance of folic acid for pregnancy. It is but crucial.
Even though the caffeine content in green tea is 30 to 60 percent less than that in coffee, its consumption is discouraged as it can interfere with numerous metabolic processes during pregnancy. According to another Brazilian study, consumption of green tea during pregnancy can result in fetal ductal constriction (pulmonary hypertension of the fetus). The University of Maryland Medical Center advises against the intake of green tea by pregnant and breastfeeding women.
Most studies recommend against the use of green tea during pregnancy. Although certain studies say limited consumption is okay, it is always best to consult your doctor. It could even be a herbal tea marketed specifically for the benefit of pregnant women – always consult your doctor first. Excess consumption of caffeine (green tea) during pregnancy can also cause abortion.