New study: Green tea is not an antioxidant
دراسة حديثة: الشاي الأخضر ليس مضادًا للأكسدة
A newly published study recently revealed how certain ingredients of green tea could help achieve a healthy and longer life.
According to a Futurity report, for a long time now, green tea has been known to offer numerous benefits, particularly its catechins known as ECG and EGCG that are believed to prolong life.
The said two substances belong to the polyphenols group, which are considered antioxidants which means they contradict or prevent oxidative stress in the body as a result of the oxygen’s aggressive free radicals.
Until now, scientists have presumed that the catechins are neutralizing these free radicals and thus prevent impairment to cells or DNA.
As the study specified, one oxygen-free radical source is metabolism. For instance, when the mitochondria, the cell’s powerhouse, are working to generate energy.
Green Tea Contains ‘Catechins’
In the new research published in Aging, the study investigators presented that at first, these polyphenols from “green tea increase oxidative stress in the short term” and have the subsequent impact of augmenting the defensive capabilities of the organism and cells.
Consequently, the catechins, as described in News-Medical.net, found in green tea that the stud authors fed to nematodes resulted in longer life, not to mention greater fitness.
According to energy metabolism professor Michael Ristow at the health sciences and technology department of ETH Zurich, that means catechins or green tea polyphenol are not actually antioxidants but pro-oxidants. It enhances the ability of the organism to defend itself, just like a vaccination.
Nevertheless, such an increase in defensive ability is manifesting not through the immune system but through the activation of genes that generate certain enzymes like catalase or CTL and superoxide dismutase or SOD.
It’s the enzymes that incapacitate the free radicals in the nematode. Specifically, they are importantly endogenous antioxidants.
Ristow is not surprised to see this kind of tool at work. His team showed in 2009 that the reason sport is promoting health is because sporting activities are increasing oxidative stress in the short term, therefore, improving the defenses of the body.
Consumption of Polyphenols
Consumption of lesser calories has the same impact, as has been shown many times in animals. Mice fed a reduced-calorie diet were found to have lived longer compared to those fed a normal, high-calorie diet. Therefore, Ristow explained it made sense that the catechins in green tea would work in the same way.
He continued saying the findings from this research interpret well by humans. The fundamental biochemical processes by which organisms that neutralize oxygen free radicals are preserved in evolutionary history and exist in everything “from unicellular yeast to humans.”
The metabolism energy professor said he, himself, is drinking green tea every day, a practice he highly recommends to others. However, he advises against the intake of green tea extracts or concentrates.
Referring to his advice, Ristow said at a certain concentration, green tea becomes toxic. He added, high-dose catechins hinder mitochondria to such a degree that cell death follows, which can be specifically harmful to the liver.
Anyone into the consumption of these polyphenols in excessive doses endangers impairing their groans. While most catechins are to exist in Japanese varieties of green teas, other types of this tea also have adequate amounts of the said polyphenols.
On the other hand, black tea has a much lower catechins content since there are mainly destroyed by a process called fermentation. Ristow elaborated that’s the reason green tea is more preferred compared to black tea.
وكالات
كشفت دراسة حديثة أن الشاي الأخضر لا يحتوي على مضادات أكسدة، على عكس المعلومة السائدة التي وردت في أبحاث قديمة.
وتقول الدراسة الجديدة التي أجريت في المعهد الفيدرالي للتكنولوجيا في مدينة زيورخ السويسرية: إن مادة الكاتيكين الموجودة في الشاي الأخضر ليست من مضادات الأكسدة.
وتوصل العلماء في دراستهم المنشورة في مجلة (أغينغ) لمعرفة كيفية تأثير الكاتيكين على جسم الإنسان، بعد دراسة أجروْها على دودة من الديدان الخيطية ووجدوا أن كميات صغيرة من الشاي الأخضر زادت في عمر الدودة.
ووَفقًا للباحثين، فإن تخطيط القلب الكهربائي و(إي جي سي جي) يزيدان من ما يعرف بالإجهاد التأكسدي لمدة محدودة، وهو الأمر الذي يزيد الوظائف الوقائية للخلايا، ليلاحظ العلماء تحسنًا في شكل الديدان. ويقول قائد الدراسة مايكل ريستو «إن بوليفينول الشاي الأخضر ليس في الواقع من مضادات الأكسدة، ولكنه يحوي مواد مؤكسدة تعمل على تحسين قدرة الكائن الحي على الدفاع عن نفسه، على غرار التطعيم» والبوليفينول عبارة عن مركبات نحصل عليها من بعض الأطعمة النباتية.
