Tea has been around for at least 5,000 years, probably longer. It originated in Asia where, legend has it, a Chinese emperor was boiling water to drink. Along came a gust of wind that blew the leaves of a nearby bush into the water. The resulting greenish brownish brew smelt so appetizing the emperor decided to drink it instead of pouring it out. And was so impressed with the taste he thought he’d continue to make, and drink, it. Thus green tea was born. Or so legend goes!
Whatever the truth behind the origins of this, the world’s second most consumed drink, the fact is that tea in all its various colors, and forms, has enjoyed a long history of popularity across many cultures, and in many countries. There are good reasons for this too. It didn’t take the Chinese long to discover that green tea had many therapeutical benefits. But first, what is green tea?
Green and black teas come from the leaves of the Camellia sinensis plant, as does oolong tea. Black tea leaves are fermented and dried, hence their black color. Green tea leaves are dried but not fermented so retain their green colour. Tea brewed from green tea retains a greenish appearance whilst black tea is black. Whilst both black and green teas are high in flavonoid antioxidants, green tea is higher courtesy of not having been fermented. According to one report, around 30% of the dry weight of green tea leaves consists of these flavonoids.
Green Tea – Particularly High In Antioxidants
The antioxidants obtained from a diet rich in fruits and vegetables are known to help reduce many serious health disorders, including cancer. But of them all, green tea stands out! Indeed, more health benefits have been attributed to regular consumption of green tea than just about any other food. It’s the ‘superfood’ of the antioxidant and healing world, containing more beneficial compounds than most other plant-based sources. These compounds include catechins, polyphenols and various kinds of flavonoids that provide a range of valuable anti-aging and therapeutic benefits:
- linoleic acid,
- amino acids and enzymes,
- cellulose, pectins, glucose, fructose and sucrose,
- methylxanthines – caffeine, theobromine and theophylline,
- minerals and trace elements – calcium, magnesium, chromium, manganese, iron, copper and zinc
- chlorophyll and carotenoids
- aldehydes, alcohols, esters, lactones and hydrocarbons
Amongst the known benefits of these compounds are improved eye and skin health, improved immune function, fewer allergies, better endurance and of course enhanced antioxidant protection.
The Much Studied Health Benefits Of Green Tea
There have been numerous studies into the health value of green tea. Significantly, a summary of population and epidemiological studies has suggested that regular green tea drinkers may benefit from a number of health benefits:
- Reduced risk of insulin resistance and diabetes and reduced cholesterol levels
- Enhanced vision protection and reduced risk of eye disease
- Lower blood pressure
- Reduced risk of heart disease and atherosclerosis
- Improved bone density
- Better memory and reduced risk of Alzheimer’s
- Reduced risk of cancer
- Reduced inflammation associated with arthritis
- Reduced appetite, leading to modest weight loss
Green Tea – Does It Help Reduce The Risk Of Developing Insulin Resistance And Diabetes?
Green tea contains anthocyanidins and/or flavan-3-ols that could help regulate blood sugar levels and improve glycemic control. The catechins in green tea, epigallocatechin gallate, or EGCG, in particular, are thought to provide antidiabetic and anti-obesity benefits whilst its anti-inflammatory properties may benefit people who have been diagnosed as pre-diabetic or who have type 2 diabetes.
Can Green Tea Help Protect Vision And Reduce The Risk Of Eye Disease?
A 2010 study looked at how effective catechins are for preventing eye diseases. The study found that increased consumption of catechins could help reduce oxidative damage and loss of vision. Granted, the study was done on rats but it found that catechins were able to pass from their digestive tract into eye tissue where they reduced oxidative stress for around 20 hours post consumption.
Will Green Tea Help Lower Blood Pressure?
With 16 diuretic compounds, 7 calcium channel blockers, 10 beta-blocking compounds and more ACE-inhibiting properties than most other plant food sources, green tea shows great promise for helping lower blood pressure. It may also significantly increase the amount of blood pumped by the heart.
Green Tea – Reducing The Risk Of Heart Disease And Arteriosclerosis
Random controlled trials suggest that those anthocyanidin antioxidants and flavan-3-ols we mentioned previously in relation to blood sugar and glycemic levels could be beneficial for cardiovascular health! That could mean a reduced risk of developing heart disease and arteriosclerosis for regular green tea drinkers.
Improve Your Bone Density With Green Tea
A study done on the bone cells of rats revealed that when these cells were exposed to the catechins in green tea, bone growth was stimulated by some 79%. EGCG appears to be the main catechin responsible for this because it stimulates an enzyme involved in bone growth. In the same study researchers discovered that green tea catechins reduced the actions of cells that reabsorb bone and improved bone mineralization generally.
Forgetting Things Or Getting Alzheimer’s? Not Anymore With Green Tea!
BuChE and beta-secretase are two enzymes found in protein in the brains of people suffering from Alzheimer’s. A 2004 study into the effects of green and black teas on Alzheimer’s disease found that both types of tea inhibit these enzymes. The study also found that tea helps prevent acetylcholine breakdown. Acetylcholine is a neurotransmitter involved in memory.
Another study looked at the effects of green tea catechins on those beta-amyloid protein plaques people with Alzheimer’s develop. These plaques are responsible for the increased oxidative stress that damages and eventually kills brain cells. The study found that giving rats green tea significantly reduced free radical levels in their brains and reduced the amount of plaque-induced memory deficits. Further studies have identified that the flavonoid epicatechin is able to cross the blood-brain barrier and is somehow able to protect the brain from the effects of these beta-amyloid plaques. Epicatechin, which is found in cocoa, blueberries, tea and grapes, has also been linked with improved brain blood vessel growth.
Antioxidant flavonoids, which are plentiful in green tea, are also believed to help protect the brain from oxidative stress generally. However, the quantity required to achieve optimum effect is unfeasible in most cases.
Reduced risk of cancer
Antioxidants in general have been proven to reduce the risks of cancer by neutralizing the free radicals that cause this damage. Green tea contains very high levels of antioxidants and for many people, this is what makes green tea such a valuable part of a healthy diet. Antioxidants are nature’s defence against free radicals. Pretty much every living organism creates some type of antioxidant as a major line of defence against damage caused by oxidation. What is oxidation? Oxidation is what happens when an atom loses an electron, leaving it with an unpaired electron in its outer shell and turning it into a free radical. Because atoms don’t like having unpaired electrons, they will immediately try to remedy this by looking for another electron to replace the one they’ve lost. In many instances, they will steal one from another atom, causing that atom in turn to become a free radical and creating a domino effect that eventually damages cellular function and can destroy DNA. Many types of cancer can be attributed to this domino effect of free radicals.
Because oxidation is an integral part of so many cellular functions – our cells create free radicals when metabolizing glucose for energy for instance – the body manufactures antioxidants to neutralize them. Antioxidants are able to donate an electron to free radicals without becoming a free radical themselves. Mammals like humans also obtain additional antioxidants from our diet, predominantly in the form of plant polyphenols found in fresh fruit and vegetables. And in green tea, which contains polyphenols and flavonoids that have shown great promise for reducing or preventing some types of cancer.
Reduced inflammation associated with arthritis
Green tea contains anti-inflammatory properties that have anecdotally been linked to helping reduce the inflammation and pain of arthritis. There is also some evidence to suggest that the powerful antioxidants in green tea may help delay or slow down arthritic processes.
Reduced appetite, leading to modest weight loss
Many weight loss supplements contain green tea extracts. Is there any evidence to justify this? The catechin EGCG is believed to help maintain good metabolic health. A 2009 review of studies conducted into the benefits of green tea for weight loss found that a common theme running through the research was that catechins, or a combination of caffeine and ECGC, did show some promise for minor weight loss. However, the review also noted that the benefits of ECGC for effective weight loss remain ambivalent overall. Some studies indicated minor positive effects and others determined that without supporting lifestyle changes, ECGC alone was not going to bring about significant weight loss.
Cure For HIV?
One of the biggest potential health benefits of green tea, or more specifically EGCG, is that it has been found to inhibit HIV. Research into this is ongoing and far from finished but just imagine – that humble brew enjoyed by so many could provide a cure to one of the biggest health issues in modern times, particularly throughout many third world countries!
Other benefits attributed to green tea include helping the liver more effectively rid the body of toxins. Additionally, green tea’s anti-bacterial properties may help prevent tooth decay by fighting the bacteria that cause plaque. Green tea has been used in traditional medicine to treat multiple sclerosis. Along with treating Alzheimer’s, green tea may also be an effective treatment for Parkinson’s.
Green Tea Is Great But Not Without Some Side Effects
However, although the benefits of green tea are considerable, over-consumption can cause some harm. It does contain caffeine, although the quantities are small by comparison to coffee. Tea polyphenols can also adversely affect iron bioavailability. A large percentage of the world’s green tea comes from China, a heavily industrialized country with high levels of pollution, particularly heavy metal contamination. Inevitably, some of these toxins end up in the country’s vegetation, including its tea plants and in the products produced from these plants.
If you have a heart condition, renal failure, significant cardiovascular problems or liver disease you should consult your doctor before taking green tea supplements. If you are pregnant or breast-feeding, limit your green tea intake to one or two cups a day to avoid the risks associated with too much caffeine.