@Mauritio said in Methionine/Cysteine restriction increases longetivity AND energy expenditure:
anybody tried sodium selenite and selenomethionine and can compare them ?
*) Forms of sélénium
The forms of selenium exist in 3 major forms:
Yeast
Sodium (selenite or selenate)
Amine acid (Selenio-Methionine or Cysteine).
Selenate or seleno-methionine (SM) are generally found on the market. Specialists classify the Se in two main categories: organic and inorganic. The inorganic salts would be supposed to be less well absorbed by the tissues. If we only refer to SM and Selenate, this is not really true, as several studies have shown it. (4)
*)
Biodisponibility
The degree of absorption of selenite is less, but sufficient, of the order of +/ 50 to 60 % against 75 % for selenomethionine. (2)
What form is the best?
Selenium in any form whatsoever, that it comes from food or supplements, organic or inorganic, is used by the body for the synthesis of selenoproteins after being first metabolized in hydrogen selene, selenium cellular storage. The surplus of selenium is converted into methylated metabolites and excreted by urine and breath. Excessive accumulation of hydrogen selenial can cause its oxidation, resulting in the production of reactive oxygen species (ROS) resulting in oxidative toxic effects in the body. (o)
All forms of selenium are well absorbed, but the absorption of selenomethionine is the best. They use the same active transport mechanism as for methionine, one of the 9 essential amino acids which can only be obtained by food, which increases the effectiveness of absorption of selenomethionine compared to the inorganic forms of the selenium.
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Recommended Daily Supply
Currently recommended nutritional supply (RDA) in adults is 55 micrograms/day.
Daily needs are 55 mcg (AJR). 1 mcg /kg of weight is optimal.
Diet (1) provides around 50 % of needs if you eat meat or legumes. A single nut from Brazil / Amazon covers needs (…).
In the event of pathology / detox, 200 - 300 mcg can be prescribed punctually.
“Too Much of A Good Thing is Bad!”
=> Selenium supplementation should not be taken every day (half-life). Except in particular cases, in the event of a detox for example, therefore punctually (2 to 300 mcg per day, in detox cure). But in this case, a contribution of curcumin would be desirable to reduce hepatic toxicity due to the impact on dehydrogenase enzymes.
Taking different forms of selenium is interesting, especially in the event of cancer prevention (recurrence).
If you exceed +/ 100 mcg/ L in the blood serum, you impact the operation of certain dehydrogenase enzymes, especially required in the Krebs cycle.
*) More details on this post, with sources and references.
Selenium: Too much of a good thing is bad. Forms and enzymes
https://mirzoune-ciboulette.forumactif.org/t1953-selenium-too-much-of-a-good-thing-is-bad#27971 (in French ) translator needed but with references from studies in English)
Sources et Références
0) Toxicité hépatique due à l’impact sur les enzymes déshydrogénases
Rôle protecteur de la curcumine
Protective effect of curcumin during selenium induced toxicity on dehydrogenases in hepatic tissue. 2005
PMID: 15881869
Selenium administration resulted in a marked decrease in the activity levels of the liver succinate dehydrogenase, malate dehydrogenase, and lactate dehydrogenase while pyruvate dehydrogenase increased significantly.
2) http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/selenium/index-fra.php
Avec références d'études.