Distinctive modulation of inflammatory and metabolic parameters in relation to zinc nutritional status in adult overweight/obese subjects.

Overweight and obesity are associated with low grade of inflammation and chronic inflammatory response characterized by abnormal production and activation of some pro-inflammatory signalling pathways. Taking into account that obesity is the direct result of an imbalance between energy intake and energy expenditure, the nutritional factors in the diet, with particular focus on zinc, may play a pivotal role in the development of obesity-associated comorbidities. Considering the potential interactions among zinc nutritional status, inflammation, overweight/obesity and insulin secretion, the aim of the present work was to clarify the influence of zinc dietary intake on some metabolic, inflammatory and zinc status parameters in adult overweight/obese subjects. We found a close interrelationship between nutritional zinc and obesity. In particular, subjects with a lower zinc dietary intake display a deeper inflammatory status, general impairment of the zinc status, an altered lipid profile and increased insulin production with respect to obese subjects with normal zinc dietary intake. Moreover, in the presence of low dietary zinc intake, the obese subjects are less capable to respond to oxidative stress and to inflammation leading to the development of obesity or to a worsening of already preexisting obesity status. In conclusion, a possible zinc supplementation in obese subjects with a deeper inflammatory status and more altered zinc profile may be suggested in order to limit or reduce the inflammation, taking also into account that zinc supplementation normalizes "inflammaging" as well as zinc profile leading to a correct intra- and extracellular zinc homeostasis.

Zinc in elderly people: effects of zinc supplementation on psychological dimensions in dependence of IL-6 -174 polymorphism: a Zincage study.

Zinc is relevant for psychological dimensions, which are altered in zinc deficiency, as in aging. Since zinc deficiency and the beneficial effect of zinc supplementation may be related to genotypes of IL-6 -174 polymorphism, the main goal was to examine psychological dimensions in relationship to plasma zinc and genetic background of IL-6 in healthy elderly subjects, recruited in Italy, Greece, and Poland, before and after zinc supplementation. On the basis of IL-6 -174 polymorphism, significant restoration occurs for PSS, especially in Greece and Poland, less for MMSE and GDS, after zinc supplementation, suggesting zinc is important in reducing stress in elderly people.

Zinc deficiency and IL-6 -174G/C polymorphism in old people from different European countries: effect of zinc supplementation. ZINCAGE study.

IL-6 SNP at position -174 is associated with age-related diseases characterized by an impaired Zn status. This polymorphism seems also relevant in regulating the expression of proteins, such as Metallothioneins (MT), involved in the modulation of Zn homeostasis. Since high IL-6 levels in elderly induce hypozinchemia, the IL-6-174 SNP may be useful to identify old subjects who are at risk for Zn deficiency. The objectives of this study are: (1) to choose old subjects who effectively need Zn supplementation and (2) to study the effect of Zn supplementation on Zn, immune and psychological status in genetically selected subjects. For this purpose, a baseline study comprising 895 healthy old subjects recruited in Central-Northern and Southern European Countries was carried out by evaluating their dietary intake, psychological and immune parameters as well as their Zn status. A Zn supplementation trial was performed in 110 old subjects selected on the basis of their plasma Zn levels and IL-6 SNP. After correcting for age and Zn intake, C- carriers displayed higher MT and lower levels of several parameters related to zinc status (plasma Zn, erythrocyte Zn and NO-induced release of Zn in PBMC) than C+ carriers. Better NK cell cytotoxicity and psychological functions (PSS, MMSE) were also found in C+ than C- carriers strictly related to the zinc status. However, independently by the polymorphism, all subjects with plasma zinc < or = 10.5microM showed the worst immune response and psychological functions. Supplementation was carried out in C+ and C- carriers with stable low plasma zinc levels ( < or =10.5microM at baseline and at 1 year follow-up) and in C- carriers with unstable plasma zinc (< or =10.5microM at baseline and >10.5microM at 1 year follow-up). C+ carriers with plasma zinc >10.5microM were not supplemented because showing the best immune and psychological conditions. After 48+/-2 days of supplementation with 10mg/day of Zn-aspartate, the NO-induced release of Zn, erythrocyte Zn and NK cell cytotoxicity increased in all groups selected for supplementation, including C- with unstable plasma zinc. In conclusion, the sole assessment of plasma Zn level is not reliable to exclude C- carriers from Zn supplementation. A possible explanation for the conflicting data on the identification of IL-6-174G as a "risk allele" based on different dietary intake in the studied population is also suggested.

Zinc, metallothioneins, and longevity--effect of zinc supplementation: zincage study.

Aging is an inevitable biological process that is associated with gradual and spontaneous biochemical and physiological changes and increased susceptibility to diseases. Because nutritional factors are involved in improving immune functions, metabolic harmony, and antioxidant defense, some nutritional factors, such as zinc, may modify susceptibility to disease and promote healthy aging. In vitro (human lymphocytes exposed to endotoxins) and in vivo (old or young mice fed with low zinc dietary intake) studies revealed that zinc is important for immune efficiency (innate and adaptive), antioxidant activity (supeoxide dismutase), and cell differentiation via clusterin/apolipoprotein J. Intracellular zinc homeostasis is regulated by metallothioneins (MT) via ion release through the reduction of thiol groups in the MT molecule. This process is crucial in aging because high MT levels are not able to release zinc, resulting in low intracellular free ion availability for biological functions. Improvement in these functions occurs in the elderly after physiological zinc supplementation. In this study, the selection of elderly subjects for zinc supplementation is discussed in relation to the genetic background of MT and pro-inflammatory cytokines, such as interleukin-6, because the latter is involved both in MT-gene expression and in intracellular zinc homeostasis.