Vitamins, ionizing radiation

At low and medium doses, it is well established that the nutritional value of proteins, carbohydrates, and fats as macronutrients are not significantly impaired by irradiation, and neither the mineral bioavailability is impacted. Like all other energy depositing process, the application of ionizing radiation treatment can reduce the levels of certain sensitive vitamins. Nutrient loss can be minimized by irradiating food in a cold or frozen state and under reduced levels of oxygen. Thiamin and ascorbic acid are the most radiation sensitive, water-soluble vitamins, whereas the most sensitive, fat-soluble vitamin is vitamin E. In chilled pork cuts at the 3 kGy maximum at 0-10°C, one may expect about 35 0% loss of thiamin in frozen, uncooked pork meat irradiated at a 7 kGy maximum at —20°C approx., 35 % loss of it can be expected [122]. 

Vitamins, effect on stability of organisms to ionizing radiation 90KFZ(1)4. 

Josephson et al. (115) conclude from their review of the eflEects of ionizing radiation treatment of foods that nutrient destruction, such as to vitamin C, in irradiated foods is no greater than that occurring when food is preserved by more conventional means. In addition, if irradiation is performed on frozen foods, the losses of vitamin C are reduced. 

The ratio of methylcobalamin to total vitamin derivatives of extractable B12 has been determined in liver from mice who were subjected to different types of injury (mechanical trauma, bums, and ionizing radiation) inflicted separately or in various combinations. A decrease in methylcobalamin was observed paralleling the severity of the damage. There may thus be a decreased synthesis of methycobalamin or an increased catabolism or leakage from the liver—or combination of these causes. The method used did not determine the nonextractable cobalamin, so that a disappearance into a nonextractable form could have been the cause (L9). 

We have used the thiobarbituric acid reaction to measure the steady state level of lipid peroxidation products accumulating in vivo in vital organs and subcellular particles (Zalkin and Tappel, 1960 Zalkin et al., 1960). Some of these results in terms of equivalent peroxide and free radicals are shown in Table II, where they are compared in amount with known toxicity of lipid peroxides and the lethality of ionizing radiations. Advantages and limitations of the thiobarbitiuic acid have been discussed previously. Comparison of the amounts of lipid peroxides found in vitamin E-deficient animals with the known lethality of ionizing radiation and... 

The benefits of food irradiation are obvious—it reduces energy demand by eliminating the need for refrigeration, and it prolongs the shelf life of various foods, which is of vital importance for poor countries. Yet there is considerable opposition to this procedure. First, there is a fear that irradiated food may itself become radioactive. No such evidence has been found. A more serious objection is that irradiation can destroy the nutrients such as vitamins and amino acids. Furthermore, the ionizing radiation produces reactive species, such as the hydroxyl... 

There are two methods of incorporating vitamin E into UHMWPE. One is to blend vitamin E with UHMWPE powder prior to consolidation. When consolidated, the blend can be crosslinked with the use of ionizing radiation. However, the presence of vitamin E in UHMWPE during irradiation reduces the efficiency of crosslinking [3-5]. The properties of vitamin-E-blended UHMWPE are covered in Chapter 16. An alternative method is the diffusion of vitamin E into UHMWPE following radiation crosslink-ing [1, 6]. The crosslinking efficiency of UHMWPE is not adversely affected in this method because vitamin E is not present during irradiation. 

See also Blood Cadmium Eosinophilia-Myalgia Syndrome Lead Radiation Toxicology, Ionizing and Nonionizing Tissue Repair Vitamin D. 

In the study of the mechanism of hereditary disease production, it is not possible to separate gene alteration from environmental effects on the genetic material. Indeed, most if not all chromosomal (or DNA) alterations that are transmitted from parent to progeny may have resulted from environmental injuries. A number of environmental factors known to injure chromosomes are ionizing and ultraviolet radiation, viruses, chemicals—including drugs, and vitamin deficiencies. 

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