Diabetes and obesity are diseases characterized by their increasing incidence every year. When comparing with healthy subjects, the serum levels of chromium (Cr) are lowered in these two diseases. Several studies conducted in laboratory animals with experimentally- induced diabetes demonstrated that supplementation with chromium ions (III) decreased glucose concentration in the blood, reduced the probability of atherosclerosis and heart attack, lowered the levels of cholesterol and low density lipoprotein (LDL). The Importance of chromium is actually challenged due to lack of clear manifestations of Cr deficiency in humans and animals. The aim of this review was to present current knowledge about Cr its role in the organism and possible mechanisms of its action also in metabolic disorders such as diabetes or obesity. In the last decade, Cr was established to be rather a beneficial than essential trace element in mammals, and has gained popularity as a nutritional supplement and a component of many multivitamin/mineral formulations, fortified food and energy drinks. Cr supplements are widespread for diabetes and obesity treatment, despite conflicting reports on its efficacy. It was suggested that Cr shows a beneficial influence upon glucose and lipid disturbances. The recent clinical trials provided evidence both in favor and against the importance of Cr in healthy and ill organisms. Unfortunately, also the molecular mechanism by which chromium affects glucose and lipid metabolism is still unclear. Beneficial effects of diet supplementation with different sources of Cr³⁺ can be potentially explained by rather pharmacological than nutritional effects.

Modern commercial pig farming systems inflict increased stress in animals, which often leads to various negative changes in the gastro-intestinal tract, especially in the case of piglets. Ban of antibiotics, used as growth promoters, has caused a need for alternatives to conventional antimicrobials in swine diets. Use of pre-/or probiotics, organic acids and plant extracts is often recommended, but it seems that zinc oxide and cooper salts, which were traditionally included in high doses to piglets diet, possess the highest efficacy. In commercial conditions feeding piglets with high doses of Zn and/or Cu stimulates piglets daily gain and decreases feed conversion factor. However, as heavy metals Zn and Cu tend to accumulate in soil and cause serious environmental pollution of soil and tap-water. Furthermore, high zinc concentrations (2500÷3000 mg/kg feed) in feed may have an impact on development of antimicrobial resistance, and may regulate the expression of genes that modify piglets’ immune response. Therefore, the use of high doses of ZnO and/or Cu salts, as growth promoter, has always been a subject of discussion, and caused different legal status of such treatment in various EU countries. This short review describes current European Food Safety Authority (EFSA) point of view on the use of ZnO in medicated feed. The higher bioavailability of recently introduced new sources or forms of these metals allows for substantial reduction of dietary inclusion rate, which should have a positive outcome for pigs health and the environment.

Studies were undertaken to compare the content and distribution of selenium in human, cow and goat milk. Selenium content of cow milk was found to be lower than that of either human or goat milk. Regardless of source, less than 3% of total milk selenium was associated with the lipid fraction. Selenium within the 120,000 × g supernatant accounted for 72, 62 and 30% of the total in cow, human and goat milk, respectively. Glutathione peroxidase occurred in all milk samples with goat > human > cow. Percent of total peroxidase activity associated with glutathione peroxidase was 29, 27 and 65 for human, cow and goat milk, respectively. Approximately 20–28% of the selenium in milk was removed by dialysis (molecular exclusion of 6–8 kDa). After gel chromatography, 8–12 selenoprotein fractions were detected in undialyzed skim milk from each species. Most of the glutathione peroxidase activity was found in the fractions corresponding to 170 and 96 kDa in milk from all species examined. The diameric form of glutathione peroxidase also appeared in dialyzed and undialyzed milk. Distinct differences in the content and distribution of selenoproteins among these species in fresh and dialyzed milk are discussed.

The concentration of selenium (Se) in milk samples obtained from 26 lacto-ovo-vegetarian (vegetarian) women was significantly greater (22.2 ± 0.8 ng/ml) than from 12 nonvegetarian women (16.8 ± 1.3). Mean GSH-Px activity (EC 1.11.1.9) in milk from vegetarians was 146% of that in milk from nonvegetarians. A significant correlation between GSH-Px activity and Se concentration was observed (r = 0.76). Likewise a significant correlation was observed between milk linoleic acid content and GSH-Px activity (r = 0.68). In undialyzed samples from vegetarian women, most of the increased content of Se was found in fractions containing proteins of 100 kdaltons (kD) or more. The high glutathione peroxidase activity in milk from vegetarians was associated with selenoproteins in the 90 to 100 kD range. A distinct 40 kD Se peak was also detected in milk from vegetarians. There was no difference in Se intake between the two groups of women. Therefore, although data from the present study show that both the quantity and distribution of Se in human milk can be modified by the maternal diet, the increased Se content and GSH-Px activity in milk from vegetarians cannot be explained by an increased Se intake.