[Antioxidants and their gastrointestinal absorption and interferences of their effects].
Antioxidants and trace elements are using by hundreds millions of people. Effective are especially mixtures of antioxidants. Usually is declared only the composition of the tablets, but nowadays it is not satisfactory. Substantial is how much of the antioxidants is absorbed and where, how it increases the antioxidant capacity in the blood, which effect it has, the stability of them and who, how much, which and when they are to be used. It is also very important which antioxidants during the detoxication of free radicals react first and therefore they are soon exhausted and whether at all or how quickly can they be reduced back to an active component. In aging the antioxidant capacity decreases, it is influenced by the season, all of factors are to be taken in account. The absorption and the effect are influenced by the state of gastrointestinal tract, including the microbiological flora, pH, the size of the molecules, sometimes by partial oxygen tension in the blood. Free radicals are generated mostly after a load and therefore it is suitable to have the antioxidants capacity on a high level, it is possible to increase it during the load and it is recommended the administration of them after the load. Some authors recommend low doses of antioxidants five times a day. In some diseases the antioxidants are effluenced from the tissues to the blood and then there is a defficit in tissues of them. Important are the interferences during the absorption, their metabolism in organism; it may decrease their level or increase their effectivness, the metabolism can infuence to which tissues are the antioxidants deposited, and how long will stay the increased level of antioxidant capacity. The speed of elimination by urine and stool is also important. It is useful to know from which and how much of isomers the antioxidant is composed, because the single isomer may have a different effect. The origin of antioxidants is important, as natural antioxidants are usually more effective than the sythetic ones. The toxicity of the substances should not to be neglected. Storing of antioxidants sometimes deteriorate them, or sometimes they are contaminated by anabolic steroids. Some substances like phytates can bind them and so decrease their bioavavilability. Lipid soluble substances need lipids in the diet, some antioxidants are differently absorbed from different sources of nutrition. Genetic equipment is important as well. It is apparent that the administration of antioxidants and trace elements is not simple and that the informations of commercial preparates is usually not sufficient, probably in the future at least may be mentioned total antioxidant capacity.
Holecek
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Mulacova nemocnice, odddlení klinické biochemie, Plzen. vholecek@volny.cz
Rokyta
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R
Vlasák
R
R
D000975:Antioxidants / Q000493:pharmacokinetics*; D006801:Humans; D007408:Intestinal Absorption
D000975:Antioxidants