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دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
are definitely necessary in our body system and دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
is a typical one.The process of oxidation in the human body damages cell membranes and other structures, including cellular proteins, lipids and DNA. When oxygen is metabolised, it creates unstable molecules called "free radicals", which steal electrons from other molecules, causing damage to DNA and other cells.
The body can cope with some free radicals and needs them to function effectively. However, the damage caused by an overload of free radicals over time may become irreversible and lead to certain diseases (including heart and liver disease) and some cancers (such as oral, oesophageal, stomach and bowel cancers). Oxidation can be accelerated by stress, cigarette smoking, alcohol, sunlight, pollution and other factors.
Antioxidants are found in certain foods and may prevent some of the damage caused by free radicals by neutralising them. These include the nutrient antioxidants, vitamins A, C and E, and the minerals copper, zinc and selenium.
Other dietary food compounds, such as the phytochemicals in plants, are believed to have greater antioxidant effects than vitamins or minerals. These are called the non-nutrient antioxidants and include phytochemicals, (such as lycopenes in tomatoes and anthocyanins found in cranberries). A diet high in antioxidants may reduce the risk of many diseases (including heart disease and certain cancers). Antioxidants scavenge free radicals from the body cells and prevent or reduce the damage caused by oxidation.
The protective effect of antioxidants continues to be studied around the world. For instance, men who eat plenty of the antioxidant lycopene (found in tomatoes) may be less likely than other men to develop prostate cancer. Lutein, found in spinach and corn, has been linked to a lower incidence of eye lens degeneration and associated vision loss in the elderly. Flavonoids, (such as the tea catechins found in green tea) are believed to contribute to the low rates of heart disease in Japan.
Another indispensiable element is دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
. Vitamin E is found naturally in some foods, added to others, and available as a dietary supplement. “Vitamin E” is the collective name for a group of fat-soluble compounds with distinctive antioxidant activities.
Naturally occurring vitamin E exists in eight chemical forms (alpha-, beta-, gamma-, and delta-tocopherol and alpha-, beta-, gamma-, and delta-tocotrienol) that have varying levels of biological activity. Alpha- (or α-) tocopherol is the only form that is recognized to meet human requirements.
Serum concentrations of vitamin E (alpha-tocopherol) depend on the liver, which takes up the nutrient after the various forms are absorbed from the small intestine. The liver preferentially resecretes only alpha-tocopherol via the hepatic alpha-tocopherol transfer protein; the liver metabolizes and excretes the other vitamin E forms. As a result, blood and cellular concentrations of other forms of vitamin E are lower than those of alpha-tocopherol and have been the subjects of less research.
Antioxidants protect cells from the damaging effects of free radicals, which are molecules that contain an unshared electron. Free radicals damage cells and might contribute to the development of cardiovascular disease and cancer. Unshared electrons are highly energetic and react rapidly with oxygen to form reactive oxygen species (ROS). The body forms ROS endogenously when it converts food to energy, and antioxidants might protect cells from the damaging effects of ROS. The body is also exposed to free radicals from environmental exposures, such as cigarette smoke, air pollution, and ultraviolet radiation from the sun. ROS are part of signaling mechanisms among cells.
Vitamin E is a fat-soluble antioxidant that stops the production of ROS formed when fat undergoes oxidation. Scientists are investigating whether, by limiting free-radical production and possibly through other mechanisms, vitamin E might help prevent or delay the chronic diseases associated with free radicals.
In addition to its activities as an antioxidant, vitamin E is involved in immune function and, as shown primarily by in vitro studies of cells, cell signaling, regulation of gene expression, and other metabolic processes. Alpha-tocopherol inhibits the activity of protein kinase C, an enzyme involved in cell proliferation and differentiation in smooth muscle cells, platelets, and monocytes. Vitamin-E–replete endothelial cells lining the interior surface of blood vessels are better able to resist blood-cell components adhering to this surface. Vitamin E also increases the expression of two enzymes that suppress arachidonic acid metabolism, thereby increasing the release of prostacyclin from the endothelium, which, in turn, dilates blood vessels and inhibits platelet aggregation.
Except these, many types of element are inconspicuous but important in our daily life such as دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
, دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
, دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
, دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
, دیدن لینک ها برای شما امکان پذیر نیست. لطفا ثبت نام کنید یا وارد حساب خود شوید تا بتوانید لینک ها را ببینید.
, etc.