Researchers at Japan’s Tohoku University studied 1003 subjects over age 70, comparing their green tea intake and mental sharpness, using a Mini-Mental State Examination, a well-accepted standardized test for measuring cognitive function.

Drinking more than 2 cups a day of green tea slashed odds of cognitive impairment in elderly Japanese men and women by 64%! And a Japanese cup of green tea is much smaller than its American counterpart-only about 3.2 fluid ounces.

And at every level of cognitive impairment-from minimal to severe-those drinking the most green tea experienced significantly less mental decline than those drinking the least:

Compared with elderly Japanese who drank less than 3 cups a week, those drinking more than 2 cups a day had a 54% lower risk of age-related declines in memory, orientation, ability to follow commands and attention.

Those drinking 4 to 6 cups of green tea a week (1 cup a day) had a 38 lower risk of declines in brain function.

Green tea’s primary protective agent is thought to be its catechin phytonutrient epigallocatechingallate or EGCG. Research shows this highly potent antioxidant:

• helps prevent the formation of B-amyloid, a protein whose accumulation is recognized as causing Alzheimer’s (Basianetto S, Eur J Neurosci Jan 2006).
• protects brain cells by chelating (removing) iron, which might otherwise produce destructive free radicals (Reznichenko L,J Neurochem, March 2006).
• helps prevent oxidative stress-induced brain cell death by “talking” to brain cells’ genes responsible for cell cycling and survival. Specifically, EGCG tells the genes in neurons to decrease production of caspase 3, an enzyme involved in initiating programmed cell death. (Park HJ, Life Sci Jan 2006; Levites Y. J Biol Chem, 2002)
• promotes memory-related learning ability by protecting cells in the hippocampus, a part of the brain involved in spatial cognition and memory-related learning ability, from free radical damage (Haque AM, J Nutr April 2006).

When confronted with a cancerous cell, green tea becomes the plant kingdom’s Arnold Schwarzenegger, helping to terminate cancer cells in a remarkable number of ways.

Laboratory cell culture studies show that green tea polyphenols are powerful triggers of apoptosis (cell suicide) and cell cycle arrest in cancerous but not in normal cells. (Cell cycling is the process cells go through to divide and replicate.)

These anticancer actions have been assumed to be due to the powerful antioxidant effects of green tea’s catechins, especially epigallocatechin-3-gallate (EGCG). This is a reasonable assumption, given that a number of studies have shown that green tea possesses remarkable antioxidant properties. In one study published in the November 2004 issue of Mutation Research,EGCG’s protective antioxidant effects against several carcinogens were found to be 120% stronger than those of vitamin C.

But while green tea’s antioxidant prowess is impressive, recent studies show it is far from the only way in which this multi-talented beverage protects us against cancer.

One of these mechanisms is green tea’s ability to inhibit angiogenesis, the development of new blood vessels. Cancer cells, which are constantly attempting to divide and spread, have an endless appetite that can only be temporarily quieted by increasing the number of blood vessels that supply them with nutrients. By inhibiting angiogenesis, green tea helps starve cancer.

Studies also show that green tea works at the genetic level, shutting off genes in cancerous cells that are involved in cell growth, while turning on those that instruct the cancer cells to self-destruct.EGCG has even been found to work as a pro-oxidant or free radical, but just inside cancer cells, where it causes so much damage that the cancer cells’ self-destruct mechanisms are triggered.

A study of ECGC’s effects on keratinocytes (the major type of epidermal or skin cell) found that this green tea compound has yet another means of correcting cancer-that of turning on the genes that direct the cancer cell to return to normal.

Green tea’s anticancer effects include its ability to inhibit the overproduction of the enzyme cyclooxygenase (COX)-2, a protein whose overproduction has been implicated as a factor in many diseases, including arthritis and cancer. COX-2 has an enzyme counterpart, called COX-1, which may be helpful to leave untouched when preventing overproduction of COX-2. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen (which inhibit both COX-1 as well as COX-2), and specific COX-2 inhibitors such as Vioxx and Celebrex (which inhibit only COX-2), have been considered as possible agents in the prevention of some forms of cancer, but their severe toxic side effects on normal cells limit their usefulness. In studies of prostate cancer cells, EGCG appears to block only COX-2 and to have no negative side effects.

Ping Tim Chan and colleagues at the Chinese University of Hong Kong fed hamsters a high fat diet to raise their triglyceride and cholesterol levels to those of humans. They then fed the hamsters differing levels of epicatechins extracted from jasmine green tea for four to five weeks and compared them with hamsters that drank green tea and a control group that had water.

Epicatechins and green tea had exactly the same effect: Both lowered blood levels of triglycerides and cholesterol more than water. The effective doses researchers used are comparable to a person drinking three daily cups of tea. Animals drinking the human equivalent of 15 cups a day lowered both triglycerides and total cholesterol by a third.

Epicatechins and green tea also lowered apoB, the main protein in harmful low density lipoprotein (LDL), by almost a half. ApoB levels predict heart disease more accurately than any cholesterol measure.

According to the researchers, epicatechins block cholesterol absorption and increase excretion of cholesterol-containing bile salts and fatty acids. The chemicals also speed the breakdown of triglycerides to fatty acids so they can be burned as energy. Other studies show that in addition to their effect on blood fats, epicatechins are powerful antioxidants that lower blood pressure and protect against cancer.

—Journal of Nutrition 1999 Jun;129:1094-101

Now, a Japanese study published in the September 2006 issue ofJAMA, suggests that drinking green tea lowers risk of death due to all causes, including cardiovascular disease.

Shinichi Kuriyama, M.D., Ph.D., of the Tohoku University School of Public Policy, Sendai, Japan, and colleagues examined the association between green tea consumption and death due to all causes, cardiovascular disease (CVD), and cancer.

The study, which began in 1994, followed 40,530 adults, ranging in age from 40 to 79, in northeastern Japan for up to 11 years. Within this region, 80% of the population drinks green tea with more than half consuming at least 3 cups a day.

Compared with participants who consumed less than 1 cup of green tea per day, those drinking 5 or more cups a day had a significantly lower risk of death from all causes and, specifically, risk of death from CVD, with women receiving even stronger protection than men:

Only weak or neutral relationships were seen between black tea or oolong tea and all-cause or CVD mortality.

While this study found no cancer-preventive benefit from drinking green tea, other large studies, including a meta-analysis of 13 studies published July 2006 in Carcinogenesis (Sun CL et al), suggest that green tea reduces risk of breast cancer. In this study, compared to women who did not drink green tea, those consuming the most green tea were 22% less likely to develop breast cancer.

Often in studies, the effects of a certain health-promoting behavior are likely to be confounded by the fact that those who try to follow a healthy lifestyle practice a variety of healthy habits. In this study, however, since green tea is the most commonly consumed beverage in Japan, it is unlikely that study participants were choosing to drink green tea primarily for their health, and thus also unlikely that the significant drop in risk of death due to all causes and CVD was due to other habits related to health consciousness.

Given the significant benefit green tea can provide, even to those who are not especially health conscious, just imagine its health-protective potential as part of your healthy way of eating! If you simply cannot start your day without a cup of coffee, try enjoying a cup of green tea at your mid-morning break, with lunch or as an afternoon pick-me-up. You’ll quickly discover green tea’s irresistible combination of invigorating and calming qualities, plus its delicious flavor, make it one of your favorite healthy habits.

Protects the Heart in Patients with Acute Cardiovascular Disease

The primary catechin in green tea, EGCG (epigallocatechin-3-gallate) confers such powerful protection that it can help prevent the death of heart muscle cells following ischemia/reperfusion injury. Ischemia is the medical term for a restriction in blood supply and therefore in oxygen and nutrients. When circulation is restored, oxidative damage occurs, and this is referred to as reperfusion injury.

EGCG prevents heart muscle damage by blocking the activation of inflammation-related compounds (including NF-kappa-B and STAT-1) that play a critical role in promoting the oxidative damage that kills heart cells in reperfusion injury. Researchers believe EGCG can be used to help minimize damage in patients with acute coronary artery disease.

For each dietary item, subjects were divided into two groups: 1) those who consumed the item five or more days per week, and 2) those who consumed the item fewer than five days per week. The researchers then measured the bone mineral density (BMD) of the women’s lumbar spines, as well as blood markers for osteoporosis risk, including levels of calcium, phosphorus, parathyroid hormone, alkaline phosphatase, osteocalcin, and vitamin D.

Women who drank green tea 5 or more days per week had an average BMD significantly higher (0.808 grams of hydroxyapatite-form calcium per square centimeter) than those drinking green tea less than 5 days per week (0.738 grams per square centimeter).

Green tea drinkers’ bone-density advantage persisted even after results were adjusted for age, body mass index, other dietary items, smoking, alcohol, physical activity and use of osteoporosis drugs.

The Tokyo team hypothesized the catechin flavonoids in green tea provided the benefits via estrogenic effects known to build bone strength and/or induce apoptosis (“suicide”) in bone-destroying cells called osteoclasts. Both mechanisms are similar to the ways in which bisphosphonate drugs like Fosamax prevent bone loss. But while these potent drugs can provoke inflammatory eye disorders, abdominal pain, nausea, vomiting, dyspepsia and diarrhea, green tea is not only completely safe, but a delicious beverage that offers a legion of other health benefits.

While black tea and oolong tea do contain flavonoids and additional antioxidants, green tea is an even better source of these health boosters because it is an unfermented tea. However, even oolong tea has been associated with slightly accelerating the metabolism (by 3% or 67 calories per day) in health studies.

Studies on the health benefits of green tea pointed to an increase in metabolism and fat burning of 78 calories per day involving adults. Depending on an individual’s size, of course, green tea burns different amounts of calories – more calories where more weight is involved, and less calories where less weight is involved.  The specific amount of calories burned depends on the current weight of the individual, but not size alone. Keeping this in mind, an individual’s ‘calorie burn OR metabolism rate’ is continuously affected by other factors – such as food combining, rate of physical activity for the day and so forth.

Researchers continue searching for a green tea weight loss link through studies.Perhaps we’ll eventually discover the connection between weight loss and green tea. Could it be the caffeine in the green tea? The amount of tea that is consumed each day? Do other foods boost the health benefits of green tea?

 Green tea contains three major components that promote fat loss: catechins, caffeine and theanine. Studies suggest that green tea compounds promote fat loss by inhibiting both gastric and pancreatic lipase, the enzymes that digest triglycerides, and fatty acid synthetase, the enzyme responsible for synthesizing fatty acids into the form in which they can be stored in the body’s adipose (fat) cells.

In a study published in the January 2004 issue of In Vivo in which mice were fed diets containing 2% green tea powder for 16 weeks, visceral fat decreased by 76.8% in those receiving green tea compared to the control group. Green tea also decreased blood levels of triglycerides (the chemical form in which most fats exist in the body).