The Clinical Significance of Micronutrients in Relation to Immune Functionsa

Abstract

In approaching the clinical significance of micronutrients, particularly in relation to immune functions, several considerations should be kept in mind. Most importantly, it must be recalled that we do not eat individual nutrients; we eat food, which is a combination of nutrients in a myriad of forms. The adequacy of any diet must be viewed in its totality, particularly as recent advances in research have made us increasingly aware of the physiological and medical implications of nutrient-nutrient interactions.Thus, one nutrient may compete with another for transport across the intestinal mucosal membranes, as with the aromatic amino acids. A nutrient, such as alcohol, can prevent adequate digestion as well as absorption of another nutrient, such as riboflavin, when present in the form in food as flavin adenine dinucleotide, or FAD.! Examples also can be provided of (a) nutrients that enhance the excretion of other nutrients, such as dietary salt promoting urinary calcium loss, (b) nutrients that interfere with binding of nutrients to tissue proteins, or (c) nutrients that diminish storage and utilization of other nutrients. On the other hand, examples can be cited of nutrients that may enhance the action of one another.One recently described nutrient-nutrient interaction relating closely to immune function is that between dietary zinc and vitamin E. It has recently been observed that zinc deficiency in rats results in a significant decrease in the plasma concentration of vitamin E, a change that is out of proportion to the concomitant decreases in concentrations of cholesterol or other lipids in plasma/ occurring under these circumstances. It is noteworthy that zinc deficiency does not have to be severe to depress the plasma concentration of vitamin E: marginal dietary zinc deficiency markedly decreases vitamin E concentrations.Zinc deficiency is well known to affect immune function both in experimental animals and in humans. 3 Furthermore, marginal zinc deficiency may be more prevalent among the population than is generally appreciated. Many common conditions frequently lead to decreased zinc absorption from the intestinal tract, such as chronic alcoholism" and "

Avaliação dos níveis séricos das vitaminas A, E, C e B2, de carotenóides e zinco, em idosos hospitalizados

“…Os indivíduos idosos ingerem cerca de metade das recomendações dietéticas (RDA) de zinco, quando fazem sua opção alimentar a partir de um cardápio variado 1,7 . Além disso, os idosos com insuficiência cardíaca congestiva e os hipertensos freqüentemente usam fármacos, como o captopril e diuréticos, que aumentam as perdas renais de zinco 20 . Níveis séricos deficitários de zinco em idosos com megaesôfago podem dever-se à disfagia e conseqüente menor ingestão de alimentos ricos em zinco, como carnes e vegetais folhosos .…”

“…Dentre as possíveis causas dessa deficiência, podem-se destacar a menor ingestão da vitamina E 25 e a má absorção 20,23 . Vinte e cinco (l 3,2%) idosos apresentaram níveis séricos de vitamina A menores do que 20 mg%, com prevalência maior em portadores de leucoses (100%), hepatopatia crônica (40%), doença pulmonar obstrutiva crônica (40%), neoplasias pulmonares (28,6%) e megaesôfago (28,6%).…”

Oral zinc therapy in patients with supposed mild zinc deficiency - a critical review

“…Fisher et al observed that the serum zinc content was 20 % lower after 2 days storage [25]. The main problem in interpretation of serum zinc estimations results on the fact, that only 1 % of body zinc circulate in serum [26]. In addition the pool of serum zinc serve as a high turnover compartment for trace elements.…”