Green Tea
Andrew Berry / October 4, 2013
Often, throughout the course of the week clients ask me about supplements. Whether it is about a particular protein powder, pre-workout or fat loss agent, I do my best to stay up to date on the current stuff out there. I have found that there are really just a few that have any real, research backed evidence of carrying out their purported benefits. It’s my hope to feature one of these supplements in a series over the next couple of months.
Green Tea
The supplement that I want to focus on today is something that I think everyone and anyone can benefit from; green tea.
Green Tea or Camellia sinensis is a type of plant native to East, South and Southeast Asia whose leaf buds are used to make tea traditionally. It grows as an evergreen shrub or small tree that is usually trimmed to below two meters when it’s cultivated for its leaves. The flowers of the plant are usually yellowish-white with 7 or 8 petals per bud.
Most teas, including green tea’s health benefits are largely due to the super high content of flavonoids. Flavonoid’s, which will be described in more detail below, are plant-derived antioxidant compounds that in recent studies have proven to be more powerful than vitamins C and E in halting oxidative stress damage to cells. (1,2) Additionally, green tea exhibits other disease fighting capabilities as well as causing a reduced risk of certain types of cancers.
History
In China, green tea is reported to have first been used more than 4,000 years ago. As the legend goes, an emperor, who was very particular about his hygiene, only drank boiled water. One day, while resting under a tree with a cup of his boiled water, a breeze blew a few leaves into his cup. The emperor continued to drink from his cup and was overcome with feelings of energy and wellbeing. Thus, the idea of drinking tea was born.
The first documented history of green tea being mentioned as a beverage is in 59 B.C. Master Wang of Chengdu got into a debate with one of his slaves over whether the slave would have to leave the home to go buy Wang his green tea. This irked Master Wang so that he wrote the highly studied “Household Slave Contract.” In this piece of work, Wang drafted that slaves have the duty to prepare tea for guests, and also that they would be subject to buying tea for their master within thirty kilometers from their master’s household.
Ok, so we know we’re talking about green tea, and we’ve heard a little history, now lets go over some terms that used to intimidate me as an undergraduate a few years back.
Polyphenols
Green tea is full of polyphenols, catechins and flavonoids.
Polyphenols, also know as polyhydroxyphenols, are a class of organic chemicals composed mainly of multiple phenol units. Phenols are phenyl rings with an alcohol (-OH) group attached. Polyphenols can be natural, synthetic or semisynthetic and the number of phenol groups within the molecule dictates the unique physical, chemical and therapeutic properties that the molecule possesses. (3)
Catechins are a type of natural phenol and antioxidant. They belong to the group known as flavan-3-ol’s that are part of the chemical family of flavonoids.
Flavonoids, or bioflavonoids are a class of plant secondary metabolites that perform a variety of functions for plants. They are the most important plant pigment in flower coloration causing the yellow, red and blue pigmentation in the petals designed to attract animals that pollinate leading to their proliferation. In higher functioning plants, flavonoids are involved in ultraviolet light filtration, symbiotic nitrogen fixation and can even act as chemical messengers and physiological regulators.
In humans, flavonoids may play an important role in the modification and regulation of many human disease states. In vitro research is showing that flavonoids have anti-allergenic (4), anti-viral (5) (including the polio virus) and anti-carcinogenic properties (6). Additionally, green tea protects against the number one killer in the United States, cardiovascular disease.
Oxidation and free radicals.
Before we talk about cardiovascular disease, oxidation, the main cause of cell breakdown and disruption should be discussed.
By definition, oxidation is a chemical reaction where oxygen causes a material to give up electrons. Burning something is an example of fast oxidation and rusting is an example of slow oxidation. Think about foods. When you cut a slice of an apple out, the flesh will turn brown over a short amount of time. This is another example of oxidation. In the human body, oxidation is happening all the time. For example, many oxidative reactions occur in the digestive system. The human body combats this by replacing those cells in a timely fashion so that there is no disruption in normal daily function. This happens continuously, 24 hours a day and is a natural process that is necessary to maintain normal cellular function.
In the body, cells are made up of molecules, which are made up of atoms. Atoms often complete their outer shells by sharing electrons with other atoms in bonds. This allows the atoms to maintain maximum stability for the molecule.
Normally, bonds don’t split in a way that leaves a molecule with an odd unpaired electron. Often times though, oxygen can cause this to happen. When oxygen reacts with a material and leaves that material with one less electron, it becomes a free radical. These free radicals are extremely unstable and react with other compounds to try and capture the needed electron. The “attacked” molecule loses its electron and becomes a free radical itself, starting the process all over. It’s a chain reaction. This process can effect and disrupt a living cell.
Antioxidants such as the epigallocatechin galate in green tea can neutralize free radicals by donating one of their own electrons ending the attack-and-steal cascade.
Unfortunately, free radicals don’t just kill cells. If that were the case, the body could just regenerate a new one. Many times, free radicals, in the process of injuring the cell, damage the DNA, which can cause a mutation. This mutation can cause the cell to grow and reproduce abnormally. This can cause diseases.
Cardiovascular Disease
It is a commonly known fact that heart disease is the leading cause of mortalities in the United States. (7) Let’s look at how green tea can help…
Cardiovascular disease is multifactorial and includes oxidative stress, abnormalities in lipid metabolism and inflammation. The anti-oxidant properties of green tea are the primary reason for its cardiovascular protecting benefits. The tea polyphenols are able to inhibit the free radicals that corrupt our cells. These free radicals form from both natural metabolic processes such as aging as well as exposure to contaminants and pathogens.
Flavonoids prevent free radicals from oxidizing LDL cholesterol (low density lipoprotein, also considered the “bad” type). When LDL becomes oxidized, it becomes a more viscous substance. This causes it to adhere to the walls of blood vessels, narrowing the passageway for blood to travel efficiently. This is a main cause of strokes. (8)
Free radicals also cause blood platelets to adhere to other cells and tissues quicker, which can trigger a blood clot within the blood vessel (i.e. thrombosis). Together with atherosclerosis, they are immediate precursors to strokes. Minimizing the actions of free radicals prevents this from happening.
When it comes to heart disease, studies show that green tea lowers the risk of heart attacks by as much as 11% with consumption of 3 cups per day. (9)
In a recent Japanese study, green tea consumption has been found to be an independent predictor for risk of coronary artery disease. It was determined that those that drank 5 or more cups per day had a 16% less likely chance of suffering from coronary artery disease. (10)
Green tea can also act as a natural blood thinner. Omega-6 fatty acids, compounds found in the polyunsaturated oils of foods such as vegetables, corn, safflower and soy, convert to a substance called arachidonic acid. The aracidonic acid breaks down into the inflammatory cytokines thromboxane A2 and prostaglandin D2. These cytokines cause platelets to clump together. The catechins in green tea such as EGCG help thin the blood by preventing the formation of these clots. They do this by suppressing the liberation of arachidonic acid and inhibiting the activity of the catalyzing enzyme thromboxane A2 synthase. (11)
Cancer Prevention
Green tea has recently been studied with some remarkable results on its effects on cancerous cells. Polyphenols in green tea are powerful triggers of apoptosis (cell death) in cancerous cells but not in normal cells. (12) These cancer cell-killing actions are believed to be due to the powerful antioxidant effects of the catechin, EGCG. (13)
ECGC inhibits the enzyme dihydrofolate reductase. (14) This enzyme, which cancerous cells need to grow, is the target of many cancer drugs currently on the market. ECGC’s structure is very similar to methotrexate, a drug that prevents cancer cells from making DNA by inhibiting the dihydrofolate reductase enzyme. Methotrexate binds tightly to the DHFR enzyme and carries side effects that are unpleasant for the users. ECGC doesn’t bind as tightly so its side effects on healthy cells are less pronounced.
Additionally, green tea is able to inhibit angiogenesis (the development of new blood vessels). (15) Cancerous cells constantly attempt to replicate and spread. This requires a lot of energy and nutrients and leads to an increase in the number of blood vessels to these cells to supply those nutrients. Green tea helps starve the cancerous cells by not allowing these vessels to form.
Studies show that green tea also works at the genetic level by shutting off genes in cancerous cells involved in growth and turning on those that tell the cell to self -destruct. (16) In one study of EGCG’s effects on keratinocytes (skin cell), it was found that this powerful antioxidant could turn on genes that direct the cancerous cell to return to normal.
Finally, green tea’s anti-cancerous effects also include the ability to inhibit the overproduction of cyclooxygenase 2 (17), an enzyme that is implicated in all types of disease states involving inflammation such as arthritis and cancer. NSAIDS such as aspirin and ibuprofen inhibit COX-2 but also interfere with COX-1, a COX-2 counterpart that is present in most tissues, most importantly in the gastrointestinal tract. COX-1 is responsible for maintaining the normal lining of the stomach as well as being active in the kidneys and playing a role in platelet function. The NSAIDS are not specific for COX-2 and end up inhibiting production of both of the cyclooxygenase isoenzymes. EGCG in green tea appears to only block COX-2 and does not carry any unwanted side effects.
Anti-Allergenic
Histamines and immunoglobulin E (IgE) are the two compounds primarily involved in triggering and sustaining an allergic reaction. A current study from Science Daily shows that a methylated form of ECGC can block the IgE receptor- the key receptor involved in an allergic response. The study was done on human basophils- blood cells that release histamines. Methylated EGCG has a stronger anti-allergenic response over normal EGCG. Now, researchers have to study the amounts needed for green tea to have a therapeutic effect. (18)
Anti-viral and Anti-microbial properties
Green tea also exhibits anti-viral activity in several ways. First, EGCG binds to the hemagglutinin of the virus that blocks it from attaching to the target receptor on cells. This stops the infection from taking place. EGCG also alters the virus cells membrane, which inhibits the virus from infecting other cells. Additionally, the amino acid L-theanine, present in green tea, activates human gamma delta T lymphocytes to synthesize interferon gamma, an antimicrobial cytokine. (19,20)
The development and prevalence of antibiotic resistant bacteria is a pressing issue in the prevention of infectious diseases. (21) There are several multi-drug resistant bacteria that cause major infections such as Staphylococcus aureus, Enterobacter, and methicillin resistant Staphylococcus aureus. When the bacteria that causes these infections are resistant to first-line antibiotics, second and third line antibiotics, which are usually more expensive, are used for treatment. This leaves a need to find and develop alternative antimicrobial agents. To combat this challenge, there has been growing interest in investigating the medicinal properties in antimicrobial plant extracts. Green tea catechins have been a leading option in the research. It has been proposed that the mechanism of action of green tea is related to EGCG preventing the attachment of pathogenic bacteria to the host cell membrane. (22)
Additionally, green tea may affect the activity of the enzyme dihydrofolate reductase that is needed by pathogenic bacteria to synthesize purine and pyrimidine to increase the thickness of the cell dermis. (23)
(24)
In an 11-year study, started back in 1994, Japanese scientists analyzed a test pool of 40,000 participants. The group was divided into those that consumed less than one cup of green tea a day and those that drank more than five cups per day. All of the participants were free of stroke, heart disease and cancer at the beginning of the study. Comparison data shows that the group that drank five or more cups each day had a significantly lower risk of death from all causes especially from cardiovascular disease and stroke. This study might partly explain why despite the high rate of cigarette smokers in Japan, the Japanese people live longer than people in any other country. (25)
Memory and Cognition
Another health benefit of drinking green tea is the improved memory and cognitive learning ability. In yet another Japanese study, it was revealed that large amounts of green tea can maintain cognitive function and might enhance learning and memory ability. (26,27). The polyphenol, EGCG is a very strong antioxidant. Due to the high usage of oxygen during normal metabolic processes, a large amount of free radicals or reactive oxygen species are produced. EGCG can penetrate the blood brain barrier and carry out its anti-oxidative affects.
Green Tea for Fat Loss and an Ergogenic Aid
Green tea can be used as a highly effective fat loss agent, specifically on the visceral fat. This is the more internal fat that surrounds the organs and intestines inside the abdominal cavity. There are three main components of green tea that assist in fat loss. They are the EGCG, caffeine and theanine, a substance known for its calming and antianxiety effects.
There are several mechanisms in which green tea helps fight the fat. Studies suggest that green tea blocks the activity of both gastric and pancreatic lipases (enzymes that digest triglycerides (fats)) as well as inhibiting the actions of fatty acid synthetase, the enzyme responsible for synthesizing the fatty acids that make up the body’s adipose tissue. (28, 29)
Catechins like EGCG inhibit the actions of an enzyme called catechol-o-methytransferase (COMT) who’s principal action is to degrade the body’s primary fat burning hormone norepinephrine (noradrenaline). (30,31) By blocking COMT’s actions more norepinephrine is available to promote thermogenesis (fat loss). Additionally, EGCG and other catechins work synergistically with caffeine to further increase the body’s metabolism.
Green tea’s ergogenic benefits don’t stop at the increase in lipolysis. In addition to keeping norepinephrine around longer, green tea allows you to train longer- at least when it comes to cardiovascular activities. Utilizing more fatty acids as a fuel source keeps glycogen levels higher allowing one to train longer. (32) Additionally, along with the increase in cardio-endurance, green tea may help you recover faster. (33) In a recent study, the catechins in green tea, possibly through their antioxidant properties, attenuated muscle damage by suppressing muscle oxidative stress and inflammation, leading to decrease in recovery time from physical performance.
Finally, green tea may even cause fat loss at the genetic level. In 2009 study that took place in Seoul, Korea, scientists studied obese rats on high fat diets. The rats were divided into three groups, one with no green tea, one with a small amount of green tea and the third with a larger amount. The changes in the expression of genes related to lipid metabolism and fatty acid oxidation were analyzed in the white adipose tissue, together with biometric and blood parameters. In those rats whose diet was supplemented with green tea, the plasma levels of both triglycerides and liver lipids were lowered. Additionally, in the white adipose tissue, the mRNA levels for adipogenic genes such as PPAR-gamma (peroxisome proliferator-activated receptor gamma), LPL (lipoprotein lipase), and FAS (fatty acid synthase) were significantly lower. Alternatively, the mRNA levels of CPT-1 (carnitine palmitol transferase), UCP2 (uncoupling protein 2) as well as the lipolytic genes HSL (hormone sensitive lipase) and ATGL (adipose triglyceride lipase) – all markers leading to increased lipolysis- were significantly increased. These results suggest that green tea may partially mediate regulation of the expression of the multiple genes involved in adipogenesis, beta-oxidation and thermogenesis in white adipose tissue. (34)
Conclusion
So, there you have it. As you can see, green tea, particularly the catechin EGCG, possesses many positive health-promoting benefits. I am sure that there are many more benefits that green tea can provide that haven’t been discovered yet. From the overwhelming evidence on the positive disease fighting, blood health marker improving and body composition changing effects from green tea supplementation, I can’t see why everyone wouldn’t include it in their supplementation arsenal. I recommend that you either brew a big pot and drink it throughout the day to supplement with water intake or take 320-640 mg daily spread out in even doses.
References
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