Is Green Tea a Fad or a Real Health Boost?

In continuation of my updates on Green tea

Green tea is a popular health trend, with many people sipping in hopes of deriving benefits from the brew.

There's nothing wrong with that, dietitians say -- green tea is a healthy drink loaded with antioxidants. But the jury's still out on many of its purported health benefits.

"Clinical trials related to green tea are still in their early stages," said Nancy Farrell Allen, a registered dietitian nutritionist in Fredericksburg, Va. "I say drink it, enjoy it. It's not going to hurt, and it might have worthy benefits to it. But nutrition is a science, and it takes time for our understanding to evolve."

Green tea's potential health benefits derive from catechins, which are powerful antioxidant compounds known as flavonoids, said Chelsey Schneider, clinical nutrition supervisor at Mount Sinai Beth Israel Cancer Center in New York City.

One catechin in particular, known as EGCG, is found at higher levels in green tea than in either white or black tea, she said.

"This compound can be even stronger than vitamin C and E, which are very, very strong antioxidants," Schneider said. Antioxidants help prevent damage to cells.

Green, black and white tea all come from the same plant, said Allen, who is a spokeswoman for the Academy of Dietetics and Nutrition.

Green tea is made from the leaves of the mature plant, while white tea is made of leaves plucked early in development. Black tea is made from green tea leaves that are laid out and covered with a damp cloth, she said.

"They dry and blacken and ferment a little, giving black tea that darker, richer flavor," Allen said. But this process also reduces levels of catechins in black tea.

Weight loss has been associated with green tea, with experts suggesting that its mixture of caffeine and catechins can enhance a person's metabolism and processing of fat, according to the University of California-Davis Department of Nutrition.

But it appears that folks have to drink a lot of green tea to get substantial weight loss benefits and carefully watch the rest of their diet, UC-Davis says.

Green tea also has been tied to heart health.

For example, green tea was shown to reduce "bad" LDL cholesterol in a 2018 study of more than 80,000 Chinese published in the Journal of the American Heart Association.

Evidence suggests catechins in green tea also could lower risk of heart attacks, help blood vessels relax and reduce inflammation, UC-Davis says.

Green tea even has been associated with a lower risk of some cancers.

The American Cancer Society says studies have linked green tea to a reduction in ovarian cancer risk. And UC-Davis said experimental models have shown that green tea might reduce risk of a variety of other cancers.

But a 2016 evidence review by the Cochrane Library concluded that there is "insufficient and conflicting evidence to give any firm recommendations regarding green tea consumption for cancer prevention."

Schneider said the research is limited. "Some small studies say green tea can maybe be preventative for certain cancers, like breast, ovarian, endometrial, pancreatic and oral cancers, but there aren't so many conclusive human trials that support that," she said.

Green tea also might help keep your brain younger. A 2014 study in the journal PLOS One found that Japanese who drank more green tea had significantly less decline in brain function, although researchers couldn't rule out the possibility that these folks might have other healthy habits that helped keep them mentally sharp.

One caveat with all of this research is that it tends to take place in Asian countries, where people drink much more green tea. There might be significant differences for Americans.

And the way you take your green tea could diminish any potential positive effects, Schneider added.

"A lot of people are adding processed white sugar to their green tea, which really makes something beautiful and healthy into something unhealthy," she said.

Adding milk or cream to your tea also might not be a good idea.

"There are some studies that say having milk in green tea can actually block the effects of you absorbing the antioxidant," Schneider said. "If it was me, I'd drink it straight up."

Dandelion tea touted as possible cancer killer

Researchers hope to test dandelion tea on patients at a Windsor, Ont., clinic after it was found the roots of the weed killed cancer cells in the laboratory.

The promising research is being led by a University of Windsor oncologist, in association with the Windsor Regional Cancer Centre.

Dr. Caroline Hamm said dandelion root extract is unique, and is one of the only things found to help with chronic myelomonocytic leukemia.

"It was really unusual to find a product that had efficacy in that area," said Hamm.

Some patients swear by it

John DiCarlo, 72, was admitted to hospital three years ago with leukemia. Even after aggressive treatment, he was sent home to put his affairs in order with his wife and four children.

The cancer clinic suggested he try the tea. Four months later, he returned to the clinic in remission. He has been cancer free for three years.

He said his doctor credits the dandelions.

"He said, 'You are doing pretty good, you aren't a sick man anymore'," DiCarlo told CBC News.

The roots of the common dandelion were ground up and made into tea. According to researchers, early results show that the tea kills cancer cells in the lab.

Using dandelion tea extract to treat leukemia is not a new idea. The Memorial Sloan-Kettering Cancer Center in the U.S., among other research sites, has been looking at the plant since at least 2010.

John DiCarlo, 72, says dandelion tea saved his life, after other medical treatments for his leukemia failed. (Steven Bull/CBC)

Hamm said the tea doesn't work for everyone and they need to find out why. The first phase of the trials will attempt to determine the right dose to administer.

Hamm was convinced that the weed contains an active ingredient, but warned "it can harm as well as benefit." She said taking dandelion extract tea could interfere with regular chemotherapy, and she urged patients not to mix the natural remedy with other cancer drugs without speaking to a doctor first.

The researchers have filed an application with Health Canada. If it's approved, Hamm expected to start the first phase of the trials in about two to three months.

Phase 1 involves 21 cancer patients where the standard of care is not working. Hamm said it would include patients with a wide variety of cancer types. The first phase should last six to eight months, she said.

Phase 2 will look at which types of cancer dandelion extract works best on, based on the results of Phase 1.

Can Green Tea, Coffee Reduce Stroke Risk? - Drugs.com MedNews

In continuation of my update on green tea...

This study of about 83,000 people suggests that drinking green tea or coffee daily might lower stroke risk by about 20 percent, with even more protection against a specific type of stroke.

"The regular action of daily drinking [of] green tea and coffee is a benefit in preventing stroke," said lead researcher Dr. Yoshihiro Kokubo, chief doctor in the department of preventive cardiology at the National Cerebral and Cardiovascular Center, in Osaka.

"If you cannot readily improve your lifestyle, try to prevent stroke by drinking green tea every day," he said.

Although it isn't certain why coffee and tea may have this effect, Kokubo thinks it might be due to certain properties in these drinks that keep blood from clotting.

In addition, green tea contains catechins, which have an antioxidant, anti-inflammatory effect. Some chemicals in coffee, such as chlorogenic acid, may cut the risk of stroke by lowering the chances of developing type 2 diabetes, he explained.

Coffee also contains caffeine, which may have an impact on cholesterol levels and blood pressure, and may cause changes in insulin sensitivity, which affects blood sugar, he added.

One expert, Dr. Ralph Sacco, past president of the American Heart Association, cautioned that this type of study cannot say for sure that the lower risk of stroke is really the result of drinking coffee or tea.

"Such association studies are still limited in [the] ability to tell whether it is some ingredients in the coffee or tea or some other behavior common to coffee and tea drinkers that is driving the protective effects," said Sacco, chairman of neurology at the University of Miami Miller School of Medicine.

Can Green Tea, Coffee Reduce Stroke Risk? - Drugs.com MedNews

Tea Drinking Linked to Reduced Risk for Atherosclerotic CVD

In continuation of my update on Tea

Habitual tea consumption is associated with a reduced risk for atherosclerotic cardiovascular disease (CVD) and all-cause mortality, according to a study published online Jan. 9 in the European Journal of Preventive Cardiology.

Xinyan Wang, from the Chinese Academy of Medical Sciences and Peking Union Medical College, and colleagues examined the association of tea consumption with the risk for atherosclerotic CVD and all-cause mortality among 100,902 general Chinese adults in 15 provinces in China. Standardized questionnaires were used to obtain information on tea consumption.

The researchers found that 3,683 atherosclerotic CVD events, 1,477 atherosclerotic CVD deaths, and 5,479 all-cause deaths were recorded during a median follow-up of 7.3 years. For habitual tea drinkers, the hazard ratios were 0.80, 0.78, and 0.85 for atherosclerotic CVD incidence, atherosclerotic CVD mortality, and all-cause mortality, respectively, compared with never or nonhabitual tea drinkers. At the index age of 50 years, habitual tea drinkers were free from atherosclerotic CVD for 1.41 more years and had a life expectancy of 1.26 years longer. Among participants who kept the habit during follow-up, the observed inverse associations were strengthened.

"Our findings give a further insight into the beneficial role of tea consumption, and have great public health implications for guiding primary prevention among general Chinese adults," the authors write.

Tea could help lower high blood pressure: Study

In continuation of my update on tea and its effect....

A new study suggests that taking tea daily could help in lowering blood pressure.The study shows that people who drank three cups of black tea a day were able to lower their blood pressure. This was seen when compared to those who drank a placebo similar in taste and caffeine content. Those who drank the tea saw a slight drop in both systolic and diastolic blood pressure over six months.

Experts however warned that drinking tea is not a substitute for blood pressure-lowering medication, but researchers said the findings show tea could still provide a benefit.

Researchers note that although the study cannot identify specific components of the tea that might lead to a drop in blood pressure, past studies have shown flavonoids, compounds found in many plants such as tea, are good for heart health.

“The message really isn't for an individual to go out and drink a lot of tea,” said Jonathan Hodgson,

More...

Drinking green tea with starchy food may help lower blood sugar spikes

In continuation on my update on green tea

Mice fed an antioxidant found in green tea  epigallocatechin-3-gallate, or EGCG  and corn starch had a significant reduction in increase in their blood sugar  blood glucose  levels compared to mice that were not fed the compound, according to Joshua Lambert, assistant professor of food science in agricultural sciences.

The dose of EGCG fed to the mice was equivalent to about one and a half cups of green tea for a human. Lambert, who worked with Sarah C. Forester, postdoctoral fellow, and Yeyi Gu, graduate student, both in food science, said EGCG was most effective when the compound was fed to the mice simultaneously with corn starch. For humans, this may mean that green tea could help them control the typical blood sugar increases that are brought on when they eat starchy foods, like breads and bagels that are often a part of typical breakfasts.

"The spike in blood glucose level is about 50 percent lower than the increase in the blood glucose level of mice that were not fed EGCG," Lambert said. 

Green tea found to reduce rate of some GI cancers

In continuation of my update on green tea.

We know that, Tea contains polyphenols or natural chemicals that include catechins like EGCG and ECG. Catechins have antioxidant properties and may inhibit cancer by reducing DNA damage and blocking tumor cell growth and invasion.

Now researchers have found that regular tea consumption, defined as  tea  consumption  at  least three times a week for more than six months, was  associated  with  a  17 percent reduced risk of all digestive cancers combined. A  further  reduction  in  risk  was  found to be  associated  with  a increased level of tea drinking. Specifically, those who consumed about two to three cups per day (at least 150 grams of tea per month) had a 21 percent reduced risk of digestive system cancers.

For all digestive system cancers combined, the risk was reduced by 27 percent among women who had been drinking tea regularly for at least 20 years," said Nechuta. "For colorectal cancer, risk was reduced by 29 percent among the long-term tea drinkers. These results suggest long-term cumulative exposure may be particularly important."

Ref : http://ajcn.nutrition.org/content/96/5/1056

Green tea found to reduce rate of some GI cancers

Green tea components may help prevent prostate cancer development in at-risk men

In continuation from my update on epigallocatechin

Prostate cancer is the second most common type of cancer in men and is predicted to result in an estimated 220,00 cases in the United States in 2015. In recent years, an emphasis has been placed on chemoprevention - the use of agents to prevent the development or progression of prostate cancer. A team of researchers led by Nagi B. Kumar, Ph.D., R.D., F.A.D.A. at Moffitt Cancer Center recently published results of a randomized trial that assessed the safety and effectiveness of the active components in green tea to prevent prostate cancer development in men who have premalignant lesions. The results will be presented at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.

Twenty percent of green tea is consumed in Asian countries where prostate cancer death rates are among the lowest in the world and the risk of prostate cancer appears to be increased among Asian men who abandon their original dietary habits upon migrating to the U.S.

Laboratory studies have shown that substances in green tea called, "catechins" inhibit cancer cell growth, motility and invasion, and stimulate cancer cell death. Green tea catechins also prevent and reduce tumor growth in animal models. Epigallocatechin-3-gallate (EGCG) is the most abundant and potent catechin found in green tea responsible for these cancer prevention effects.

The goal of this trial was to evaluate if a one-year intervention with green tea catechins could suppress prostate cancer development in men who had high-grade intraepithelial neoplasia (HGPIN) or atypical small acinar proliferation (ASAP). The researchers used decaffeinated green tea capsules called Polyphenon E that contained a mixture of catechins that predominantly contained EGCG at a dose of 200 mgs twice a day.

Green tea components may help prevent prostate cancer development in at-risk men

Drinking tea flavored with herbs may improve mood and memory

  Chamomile      Rosemary 

 Peppermint

The herbs peppermint, chamomile, rosemary and lavender have been proven to have an impact on mood and memory, with significant benefits displayed for older people, according to new research from Northumbria University.

Researchers from the University's Department of Psychology have found that drinking peppermint tea improves alertness, while chamomile tea has a calming effect. They also found that smelling the aromas of rosemary and lavender impacted on memory in people over 65, with the scent of rosemary enhancing their memory, while lavender impaired it.

The findings have been presented at the annual British Psychological Society Conference in Nottingham this week (26-28 April 2016).

In one study, the researchers asked 180 volunteers to consume either a chamomile or peppermint tea drink and tested their cognition and mood before and after drinking. A control group drank hot water for comparison.

They found that peppermint enhanced and aroused both mood and cognition, helping to improve long term memory, working memory and alertness, while chamomile had a calming and sedative effect which significantly slowed memory and attention speed.

In a separate study, 150 healthy people aged 65 and over were placed in rooms which had been scented with rosemary and lavender essential oils, or a control room which had no scent. They were asked to undertake tests that assessed their prospective memory - the ability to remember to do something at a given time, such as taking medication, or after receiving a prompt, such as posting a letter after seeing a post box. They also completed a mood assessment test.

Those who had been in the rosemary scented room displayed significantly enhanced prospective memory, with test scores 15% higher than those who had been in the room with no aroma. They were also more alert.

In contrast, those who had spent time in the lavender scented room displayed significantly increased calmness and contentedness, with a decrease in their ability to remember to do something at a given time.

Dr Mark Moss, Head of the Department of Psychology, said: "Peppermint has a reputation for being psychologically or mentally alerting. It picks you up and makes you feel a little bit brighter, so we endeavoured to test this out by giving people peppermint tea, or chamomile tea, which is a more calming drink and then put them through some computerised tests. We found that those people who had drunk the peppermint tea had better long-term memory. They were able to remember more words and pictures that they had seen. In contrast, the people who had the chamomile were slower in responding to tasks.

"Rosemary meanwhile has a reputation about being associated with memory - even Shakespeare said 'rosemary is for remembrance' - and it's also associated with being invigorating. We have found that people are more alert after being in a room that has rosemary aroma in it. We tested prospective memory - our ability to remember to remember to do something - on people over 65 years of age, to see if we could improve their ability and we found that rosemary could do that. This is potentially very important because prospective memory, for example, enables you to remember to take your medication at certain times of the day.

Drinking tea flavored with herbs may improve mood and memory

Matcha green tea kills breast cancer stem cells

MATCHA, the Green Tea packed with antioxidants, is often hailed as containing properties which prevent disease.

Scientists in Salford, UK have shed a ray of light on the claim by testing it on cancer stem cells - with surprising results.

In research published in the journal Aging, a team from the Biomedical Research Centre at the University of Salford, used metabolic phenotyping on cell lines of breast cancer stem cells and found that Matcha "shifted cancer cells towards a quiescent metabolic state" and stopped their spread at a relatively low concentration (0.2 mg/ml).

They also found that the signaling pathways that promote cancer stem cells indicated that Matcha "strongly affected mTOR signals, weakening components of the 40S ribosome. This raised the possibility that Matcha could be used in place of chemical drugs such as rapamycin.

Michael Lisanti, professor of translational medicine at the center, explained: "Matcha green tea is a natural product used as a dietary supplement with great potential for a range of treatments. But, the molecular mechanism underpinning all that remains largely unknown.

"By using metabolic phenotyping, we found that the tea is suppressing oxidative mitochondrial metabolism - in other words it is preventing the cells from 're-fuelling' and therefore they become inactive and die.

"The effects on human breast cancer cells were very striking; the active ingredients in matcha having a surgical effect in knocking out certain signaling pathways.

"Our results are consistent with the idea that Matcha may have significant therapeutic potential, mediating the metabolic reprogramming of cancer cells."

The team who specialize in identifying non-toxic methods of killing cancer stem cells recently found that Earl Grey tea ingredient, Bergamot kills cancer cells and works as an anti-cholesterol agent.

Ref : https://www.salford.ac.uk/news/articles/2018/green-tea-prevent-cancer-cells-from-refuelling

Plant flavonols significantly reduce Alzheimer’s risk

A new study published in the journal Neurology in January 2020 concludes that increasing the intake of plant flavonols steeply reduces the risk of Alzheimer’s dementia (AD) by up to a half. In other words, AD could be prevented in many people simply by regularly eating and drinking more foods containing these compounds such as tea, oranges, and broccoli.

Alzheimer’s disease

AD is a progressive brain disorder in which the individual loses cognitive skills, including memory and thinking skills, and the ability to perform simple tasks. It is by far the leading cause of such disorders and affects over 5 million Americans.

One study was carried out on over 900 people, who were part of a community-wide ongoing larger research project called the Rush Memory and Aging (MAP) Project. These participants were assessed yearly for their neurologic health and dietary patterns, for an average of 6 years, but some for as long as 12 years. The average age was 81 years, and 3 out of 4 were female.

The findings

In the first study, 220/921 participants developed AD during the study. The risk of AD fell with a greater intake of flavonols. This finding held good even after the researchers adjusted for other health-associated factors – because those with the highest total flavonol intake were also the best educated, most active and took part in more cognitive activities. They also accounted for genetic factors like the presence of the APOE4 gene, and for cardiovascular risk factors that could influence the risk of AD, such as diabetes mellitus, history of heart attack, or stroke, or hypertension.

When classified into five groups based on decreasing flavonol intake, the participants in the first group (highest intake) consumed over 15 mg of flavonols a day. Compared to those in the lowest fifth (about 5 mg a day), these individuals showed an approximately 50% reduction in AD risk.

In concrete terms, 28 of 186 patients in the highest-intake group developed AD, vs. 54 of 182 in the lowest-intake group.

With respect to individual flavonols, kaempferol intake was linked to a reduction of almost 50%, and both myricetin and isorhamnetin by 40% each. A fourth flavonol, called quercetin, had no noticeable effect on AD risk.

Participants with the highest flavonol intake drank about one cup of black tea a day. Kale, and about a glass of red wine each day, could also supply flavonols.

Sources of flavonols

Kaempferol is richly present in green leafy vegetables, including spinach, broccoli, beans, tea and kale – and also in tea. Isorhamnetin-rich foods include olive oil, red wine, pears and tomato sauce. Myricetin is found in tea, kale, oranges, tomatoes and red wine.

Researcher Thomas Holland says, “More research is needed to confirm these results, but these are promising findings. Eating more fruits and vegetables and drinking more tea could be a fairly inexpensive and easy way for people to help stave off Alzheimer's dementia.”

Implications

Many scientists disagree with the emphasis on flavonols. Though these were thought to have antioxidant activity in the body, this theory was discredited many decades earlier. Antioxidant activity ceases when they are ingested and subjected to the activity of enzymes in the digestive tract.

They point out that flavonols are found in many plants, fruits and vegetables, which have been associated with good health for centuries. Nutritionists say that the AD-delaying effects of such foods are likely due to other plant chemicals which are relatively more abundant. On the other hand, taking flavonol pills or tea extracts is unlikely to produce the same healthful effect, and overdoses could be counterproductive.

This is not to say that eating more flavonol-rich foods or drinking a cup of black tea in the morning would hurt, since any foods containing these chemicals would also contain many more healthful compounds including vitamins, minerals and plant fiber. Holland makes a valid point with his conclusion: “'With the elderly population increasing worldwide, any decrease in the number of people with this devastating disease, or even delaying it for a few years, could have an enormous benefit on public health.”

https://n.neurology.org/content/early/2020/01/29/WNL.0000000000008981

Plant flavonols significantly reduce Alzheimer’s risk

Matcha green tea kills breast cancer stem cells

MATCHA, the Green Tea packed with antioxidants, is often hailed as containing properties which prevent disease.

Scientists in Salford, UK have shed a ray of light on the claim by testing it on cancer stem cells - with surprising results.

In research published in the journal Aging, a team from the Biomedical Research Centre at the University of Salford, used metabolic phenotyping on cell lines of breast cancer stem cells and found that Matcha "shifted cancer cells towards a quiescent metabolic state" and stopped their spread at a relatively low concentration (0.2 mg/ml).

They also found that the signaling pathways that promote cancer stem cells indicated that Matcha "strongly affected mTOR signals, weakening components of the 40S ribosome. This raised the possibility that Matcha could be used in place of chemical drugs such as rapamycin.

Michael Lisanti, professor of translational medicine at the center, explained: "Matcha green tea is a natural product used as a dietary supplement with great potential for a range of treatments. But, the molecular mechanism underpinning all that remains largely unknown.

"By using metabolic phenotyping, we found that the tea is suppressing oxidative mitochondrial metabolism - in other words it is preventing the cells from 're-fuelling' and therefore they become inactive and die.

"The effects on human breast cancer cells were very striking; the active ingredients in matcha having a surgical effect in knocking out certain signaling pathways.

"Our results are consistent with the idea that Matcha may have significant therapeutic potential, mediating the metabolic reprogramming of cancer cells."

The team who specialize in identifying non-toxic methods of killing cancer stem cells recently found that Earl Grey tea ingredient, Bergamot kills cancer cells and works as an anti-cholesterol agent.

Ref : https://www.salford.ac.uk/news/articles/2018/green-tea-prevent-cancer-cells-from-refuelling

Gren tea for new type of H1N1 Flu ......

In continuatation of my update on Epigallocatechin gallate (EGCg), I find this info something different and interesting too. We are aware about the antioxidant and anticancer activities of this compound, but now researchers from Central Research Institute of ITO EN, Ltd., & School of Pharmaceutical Sciences, University of Shizuoka have found the same compound to inhibits flu infection. As per the researchers claim, the compound had an inhibitory effect against three types of influenza viruses, including the swine-origin H1N1 virus that caused pandemic flu in 2009, and that its effect did not depend on the type of virus. These findings once again suggest that green tea is effective in preventing flu.

Gargling with green tea has already proved to prevent the onset of seasonal flu. It has become clear that catechin, a major type of polyphenol in green tea, plays a major role in prevention of flu infection, and that, among different types of catechin, EGCg displays the strongest antiviral activity. More interestingly, the researchers have conducted examinations to see if EGCg also shows antiviral activity against the new type of H1N1 virus, regardless of viral subtypes.

Solutions containing three types of viruses including the H1N1 virus were mixed with EGCg extracted from green tea. The mixture was added to cultured cells, which were thus infected. The cells were incubated for a set period of time, and the number of infected cells was counted. The concentration of EGCg at which virus infection was inhibited to 50% of the level of infection without EGCg was calculated.

The experiments showed that EGCg prevented flu virus infections at lower concentrations than Amantadine (a drug used to prevent and treat flu). A typical concentration of EGCg in green tea infused from a teapot is reported as 5,000-7,000 micromoles/L. Therefore, these results indicate that green tea diluted 1,000-fold or more is effective to halve infections by three types of viruses, including H1N1.

Those interested to know the details about green tea can visit the site.

Ref : http://www.itoen.co.jp/eng/corporate_info/index.html

Green tea shows promise against two types of tumors, HHS

In continuation of my update on green tea

Researchers lead by  Dr. Thomas Smith at The Donald Danforth Plant Science Center and his colleagues at The Children’s Hospital of Philadelphia, have found that a compound found in green tea shows great promise for the development of drugs to treat two types of tumors and a deadly congenital disease. 

Dr. Smith and his colleagues discovered that two compounds found naturally in green tea are able to compensate for this genetic disorder by turning off GDH in isolated and when the green tea compounds were administered orally. The Smith lab also used X-ray crystallography to determine the atomic structure of these green tea compounds bound to the enzyme. With this atomic information, they hope to be able to modify these natural compounds to design and develop better drugs. 

Interestingly, two other research groups have validated and extended these findings to demonstrate that blocking GDH with green tea is very effective at killing two different kinds of tumors; glioblastomas, an aggressive type of brain tumor, and tuberous sclerosis complex disorder, a genetic disease that causes non-malignant tumors to grow on a number of organs. 

More...  

Seeds of tropical shrub guarana contain ten times more amount of catechins than green tea

 

In continuation of my update on catechins. 

The millions of people who consume green tea all over the world benefit from the catechins it contains. Catechins are a class of chemical compounds with anti-oxidant and anti-inflammatory properties, among other healthy ingredients. Researchers at the University of São Paulo's Public Health School (FSP-USP) have discovered that guarana (Paullinia cupana) is a worthy competitor, at least as far as catechins are concerned: the seeds of the tropical shrub, used in fizzy drinks that are among the most popular in Brazil, as well as in over-the-counter supplements, contain more than ten times the amount of catechins found in green tea.

 Catechins

A clinical trial with healthy human volunteers has demonstrated that guarana is a rich source of catechins, which, when properly absorbed, reduce the oxidative stress associated with the development of neurodegenerative and cardiovascular disorders, as well as diabetes, cancer, inflammation and premature aging due to cell death, among other conditions harmful to health and wellbeing.

"Guarana has always been seen above all as a stimulant, especially by the international scientific community, because of its high caffeine content. We also found few Brazilian scientific studies that seek to identify other biological effects of guarana," said Lina Yonekura, the principal investigator for this research and currently an assistant professor at Kagawa University's School of Agriculture in Japan. "This pioneering assessment of the absorption and biological effects of its catechins in human volunteers should foster interest in guarana as a functional food on the part of scientists, the market, and society in general."

The paper with the results of the study is featured on the cover of the latest issue ofFood & Function, published by the Royal Society of Chemistry in the United Kingdom as one of the "Hot Articles in Food & Function 2016.

The month-long study was conducted in two stages. After selecting volunteers who were healthy but slightly overweight and with a moderately elevated risk of cardiovascular disease, the researchers measured baseline parameters on the first day and evaluated the same items again on day 15 after a the implementation of a controlled diet.

The participants were then asked to take guarana at home every morning before breakfast for the next fortnight. They were given bottles containing guarana seed powder and instructed to prepare a daily drink with the contents of one bottle (3 g of guarana powder) in 300 mL of water.

This procedure ensured that each participant acted as his or her own control. The researchers compared the same volunteers' blood tests at different times to avoid the influence of variability between individuals. The acute effect of guarana was measured one hour after the participants drank the solution on day 1 and day 15. The prolonged effect was assessed after overnight fasting on the same days.

The researchers assessed the extent to which guarana affected oxidative stress markers during the two-week intervention period. They also performed a detailed study to evaluate the subjects' absorption of catechins and their metabolites, as they had found no information in the scientific literature on the bioavailability of these compounds in guarana.

The oxidative stress markers included oxidation of low-density lipoprotein (LDL), popularly known as bad cholesterol. LDL is essential to an organism's proper functioning because it is the main particle that carries cholesterol to cells. Cholesterol is a structural component of all cell membranes and is used to manufacture steroid hormones (estrogen and testosterone). When oxidized, however, LDL causes atherosclerosis and increases the risk of cardiovascular disease. The tests performed by Yonekura's team showed an increase in oxidation resistance of the LDL in the blood samples taken from the volunteers after they drank guarana.

They also performed a comet assay, also called single cell gel electrophoresis (SCGE), a technique for quantifying and analyzing DNA damage in individual cells due to various factors, including oxidative stress. In this case, lymphocyte DNA in blood samples taken one hour after guarana intake was less damaged than expected when submitted to an oxidizing environment, indicating the presence of anti-oxidant substances or enhanced performance of the lymphocytes' enzymatic anti-oxidant system.

"All these markers depend on the presence of catechins in the bloodstream," Yonekura said. "The improvement in the parameters we assessed was associated with a rise in the concentration of plasma catechins after guarana intake, showing that guarana was indeed responsible for this effect."

Moreover, she went on, the guarana catechins strengthened the cells' native anti-oxidant enzymes, especially glutathione peroxidase, catalase, and superoxide dismutase, which combine to convert superoxide into peroxide and finally into water, protecting cells from the oxidative damage caused by their own metabolism of outside factors.

The tests showed increased glutathione peroxidase and catalase activity both shortly after guarana ingestion and on the following day.

"These results are exciting, suggesting that the bioavailability of guarana catechins is equal to or greater than that of green tea, cocoa and chocolate catechins," Yonekura said. "In fact, their bioavailability was sufficient to have a positive effect on plasma anti-oxidant activity, protect erythrocyte DNA, reduce plasma lipid oxidation, and increase anti-oxidant enzyme activity. We hope the results lead to heightened interest in guarana as the species is native to the Amazon, and Brazil is practically the only country that produces it on a commercial scale."