Selenium as a food supplement
In a critical review of pharmaceutical information in June 2005 noted that the currently available studies could not provide evidence for a benefit of an additional dose of selenium in any context. Although a positive influence of various cancers seems possible, on the other hand, favoring other cancers not unlikely. The "SELECT" study ("Selenium and Vitamin E Cancer Prevention Trial") should provide information in this regard and be completed in 2013. However, this was discontinued in October 2008, as was demonstrated during the study that there is no better protective effect compared to placebo and a benefit could be excluded. In this study, although an increased incidence of prostate cancer under the administration of vitamin E and an increased diabetes inception of selenium administration was even found, but neither was statistically significant.
As part of the recent analysis of data from a study Saverio strand came from the University at Buffalo to the conclusion that, of the 600 patients, the selenium income (daily. 200 micrograms) after almost eight years, about ten percent of type 2 diabetes were diagnosed. In the placebo-control group, there were only six percent. To date, no potential cause for the increased risk of diabetes was found. High selenium concentrations in the blood correlate with the risk of developing diabetes. Thus, the pharmaceutical information comes from February 2008 to the end: "A critical attitude towards largely unoccupied concepts behind which of course is a big financial interest, has once again confirmed." However, the study location is not explicit in this respect. So the study of train are et. al. subject to methodological errors, such as the lack of a previous family history that should have ruled out an increased familial prevalence of diabetes mellitus in the selenium group, and the fact that the subjects studied were those who were highly exposed solar radiation and chemicals, which is why the results were transmitted poorly to "average" subjects. In addition, the risk of diabetes lies in both the placebo and in the selenium group under the American average. Other studies suggest a further inhibitory effect of selenium on the development of diabetes mellitus close, including a recently published by Tasnime Akbaraly (University of Montpellier) study carried out on 1,162 men and women.
A paper from the year 2012 shows a positive effect of selenium only when a selenium deficiency exists, otherwise it is more likely to develop diabetes mellitus. A large meta-study from the year 2013 shows no protective benefit of selenium substitution with respect to cardiovascular diseases. There were increased type 2 diabetes cases in the selenium substitution group, but the difference was not significant. But there was more to alopecia and dermatitis.
Sodium selenite and thyroid hormones
Selenium plays an important role in the production of thyroid hormones, particularly in the "activation" of thyroxine (T4) to triiodothyronine (T3).
Selenium is an integral part of an enzyme, the thyroxine 5'-deiodinase, which is responsible for the removal of an iodine atom from T4. By this deiodination occurs T3. Selenium deficiency leads to a deficiency of thyroxine-5'-deiodinase, whereby only a portion of the available T4 can be deiodiert. Since T3 is much more effective in metabolism, resulting from a T3-deficiency hypothyroidism (hypothyroidism). An additional intake of selenium supplement (sodium selenite) daily in high doses of 200-300 micrograms is indicated by a doctor for clarification. As in Hashimoto's thyroiditis, this can also reduce the inflammatory activity.
Evidence
The quantitative determination of trace (0.003%) of selenate can be done by means of polarography electrochemically. In 0.1 M ammonium chloride solution, a stage show at -1.50 V (vs. SCE). Ultratrace itself offers the atomic spectrometry, with 100 ug / l (ppb), by graphite furnace AAS 0.5 and 0.01 micrograms per hydride / l selenium can be detected by flame AAS.
Safety
Selenium and selenium compounds are toxic. Direct contact damages the skin (blistering) and mucous membranes. Inhaled selenium can lead to protracted lung problems.
Poisoning by excessive intake of selenium is called selenosis. A selenium intake of more than 3000 micrograms / d can lead to liver cirrhosis, hair loss and heart failure. Employees in the electronics, glass and paint industries are considered at risk. According to other sources come from just 400 g / d of poisoning on as nausea and vomiting, hair loss, nail changes, peripheral neuropathy and fatigue.