Assist. Prof. Dr. NAGAM KHUDHAIR MAHDI Biochemistry and Molecular Biology

Diabetes and Selenium

   Diabetes is a metabolic disorder that results from a lack of insulin production or its effect, with high blood sugar as one of its main signs. According to the International Diabetes Federation (IDF), in 2019, about 463 million adults between the ages of 20 and 79 were diagnosed with this disease in the world, of which 15.5 million cases occurred in Brazil, which is the fifth country in the world in terms of the number of diabetes cases in this Age group. About 90% of diabetes cases correspond to type 2 diabetes, which is a multi-cause disease mainly associated with genetic and lifestyle factors, such as being overweight or obese; sedentary lifestyle; Diets low in whole grains, fruits, nuts and seeds; diets rich in red meat, sugary drinks, and processed meats. Hyperglycemia, a feature of diabetes, is associated with both acute and chronic complications of this disease, negatively affects quality of life, and has a higher mortality rate in patients with diabetes. Furthermore, it has been reported that hyperglycemia causes an increase in the production of reactive oxygen species, which causes oxidative stress and influences the development of diabetes. Antioxidant nutrients play an important role in defending our bodies by reducing oxidative stress and preventing the onset of chronic diseases, primarily by neutralizing free radicals and their metabolic effects. Vitamins A, C, and E and minerals, such as zinc, selenium (Se), copper and manganese, found in our diet, are among the nutrients associated with antioxidant status.

 Selenium (Se), one of the essential nutrients for humans and animals with the greatest antioxidant potential, is both organic and inorganic in nature. Its inorganic form, selenite and selenite salts, mainly accumulates in plants via the sulfur absorption pathway. Plants absorb these salts from the soil and convert them to the organic form, selenomethionine and selenocysteine, which can be incorporated into proteins that originate from selenoproteins. Animals and humans cannot manufacture these ingredients and must eat them as part of their diet.

Se concentration in plants is directly related to plant species, soil concentration, soil type, accumulating capacity, pH, salinity, organic matter, and redox reactions. Thus, dietary intake of Se varies with different countries and regions, and the type of food consumed. In plant tissues, its concentration depends on the geographical area, its level and availability in the soil. In the tissues of animals, it depends on the amount ingested. Foods rich in selenium are meat, cereals, grains and dairy products. Meat is the main source of consumption, because skeletal muscle is the main selenium storage site, accounting for about 28-46% of the total selenium pool. The selenoprotein family consists of 25 eukaryotic genes, with 25 human genes. All of these proteins contain selenocysteine residues in their pre-determined primary structure. These selenoproteins are responsible for the function and regulation of thyroid hormones, glucose metabolism, improved male fertility, and anti-inflammatory actions. They are also indirectly involved in the wound healing mechanism as reducers of oxidative stress through glutathione peroxidase (GPX), a major selenoprotein found in the human body, helping to control the excessive production of free radicals at the site of inflammation.

Therefore, attention was drawn to selenium for its antioxidant properties, as antioxidants protect cells from damage. Evidence indicated that selenium supplements reduce the possibility of developing cancerous diseases, while studies indicated that there are no benefits for this. The case of selenium deficiency is low, with pathological cases. It is related to a low level of selenium such as HIV and Crohn's disease, and patients who are fed intravenously, in these cases, doctors recommend the use of selenium supplements. The total amount of selenium you should get from food or even supplements, and a safe upper level of selenium is 400 micrograms per day for adults and above that is considered an overdose.

It was initially expected that selenium would be beneficial for diabetic patients, given that type 2 diabetes mellitus (T2DM) is associated with oxidative stress. In fact, selenium (as selenate) has antidiabetic, and insulin-mimicking effects, at high doses above nutrition. Consequently, the evidence differed that selenium had an effect on diabetes, and studies showed that there is a possibility of developing type 2 diabetes. Other studies indicated that the incidence of diabetes was higher in European men who had low plasma selenium concentrations.

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