Georg Brubacher

Cancer Mortality Inversely Related to Plasma Levels of Antioxidant Vitamins

Aggressive oxygen species (such as superoxide anion, hydroxyl radical, singlet oxygen and longer-lived reaction products (e.g. hydroperoxides, alkenals) have been implicated in cancerogenesis but it is very difficult to show their direct role in vivo. Indirect evidence can be obtained from the inspection of the body’s multilevel defense system against oxygen radicals which includes essential antioxidants, i.e. β-carotene and the vitamins A, C and E. Since the dietary supply of the latter can vary considerably cancerogenesis might, at least in part, be inversely related to the status of antioxidant vitamins. There is growing evidence in animals and humans in favour of this concept. In animals vitamin A deficiency results in metaplasia whereas experimentally induced tumors can be diminished by β-carotene, vitamins A, C and E. In the human many dietary surveys have convincingly shown that the intake of fresh fruits and leafy green-yellow vegetables as well as the calculated consumption of the above mentioned essential antioxidants is inversely related to the mortality from cancers (1–4). Dietary surveys have, however, inherent weaknesses and thus require confirmation by the measurement of plasma antioxidants in prospective studies.

THE OCCURRENCE OF THIAMINE METABOLITES IN RAT LIVER AFTER ADMINISTRATION OF 35S-LABELED THIAMINE

It is a well-known fact that, according to their dosage, substances can be metabolized in the animal body to different products. Even after administration of unphysiologically high doses of normal food ingredients, metabolic reactions may occur which do not take place under normal conditions and must be ascribed to detoxication reactions. Such reactions must be considered especially when high doses of substances are administered which are normally present in the food in very small quantities, as for instance vitamins, or which occur as intermediary metabolites. Obviously, when experiments with such substances are carried out under physiological conditions and only very small doses are administered, it may be difficult to demonstrate and identify metabolites. It is known that thiamine is converted to thiamine diphosphate in the animal body, and that this derivative is the coenzyme of pyruvate decarboxylase and of transketolase. A. Rossi-Fanelli et al.,l K. H. Kiessling2 and, later, other authors have pointed out that, in addition to thiamine diphosphate, thiamine triphosphate is present in organs such as liver, kidney, and brain; the function of this metabolite, however, is not yet absolutely clear. It does not appear to act as a coenzyme of pyruvate decarboxylase and transketolase.3-6 On the other hand, it was reported that thiamine triphosphate, like adenosine triphosphate, is hydrolyzed to phosphate and thiamine diphosphate by myosin.6 In addition, it was shown that thiamine triphosphate is used as phosphate donator for the phosphorylation of glucose? In addition to thiamine diphosphate and thiamine triphosphate, thiamine monophosphate was found by H. P. Gurtner8 in peripheral nerves. The forms present in greatest quantity were thiamine diand monophosphate. The experiments reported below were carried out to obtain more information on the possible role of thiamine triphosphate or other metabolites of thiamine.

Petites variations du taux sanguin de vitamine A et leurs incidences sur la perception visuelle

The purpose of this study was to find out a simple perceptual visual test that gives the possibility to detect the visual incidence of slight variations of the vitamin A blood rate. The visual function was tested in 30 young subjects without refraction problems at the same time as blood concentration of vitamin A was measured. Visual tests comprised visual acuity at high and low luminance level, contrast sensitivity, glare sensitivity as well as attenuation characteristics of the eye toward flickering stimuli. Among all these tests, only the flicker test showed some relation with the plasma vitamin A levels, which were situated between 35 and 75 mcg/100 ml.

Low Plasma Levels of Vitamin A and E during Weight Reduction

Current knowledge and the growing awareness of adverse consequences of human obesity to health has resulted in a frequent use of different weight reducing regimes within the last years. Much attention has been paid in the past to the effect of weight reduction on atherosclerotic risk factors and numerous reports have been published regarding protein and carbohydrate metabolism in obese subjects. Very few studies have evaluated the vitamin status of patients undergoing rapid and/or longterm weight reduction, particularly in grossly obese children and adolescents (1, 2).

A nutritional survey of 38 single elderly persons with free choice of food

The nutritional habits of 38 randomly selected single aged people with free choice of food have been investigated by the precise weighing method. Blood serum levels of the vitamins A, C, and E and of beta-carotene and biotin were analyzed, and the nutritional status with respect to the vitamins B1, B2, and B6 was examined by the transketolase-test, the glutathione-reductase-test, and the glutamic-acid-oxalo-acetic-transaminase-test. In relation to the desirable daily supply of nutrients and other dietary components the food was deficient in the vitamins B1, and B6 and in magnesium. For women an additional calcium-deficiency was demonstrated. The dietary fat content, however, was found to be high (44% of total calorie intake). The results of the blood analyses suggest an insufficient dietary supply of vitamin B1, partly also of the vitamins B6 and C. The total caloric intake was found to be rather low with respect to the age.