Ivanka Miletić

Effects of zinc on the mineralization of bone nodules from human osteoblast-like cells

Zinc is an important mineral that is required for normal bone development. However, the direct effects of zinc on the mineralization of bone cells of human origin are not clear. The objective of this study was to determine the effects of zinc on the differentiation of SaOS-2 human osteoblast-like cells and the formation of mineralized bone nodules. Cells were cultured for 8 d and then transferred to zinc-free medium and treated with varying concentrations (0–50 μM) of zinc. Alkaline phosphatase (ALP) activity was used as a measure of osteoblast differentiation, and bone nodules were detected by von Kossa staining. After 4, 6, and 8 d of treatment, zinc increased ALP activity at 1 and 10 μM, but decreased activity at 50 μM. After 9 d of treatment, zinc increased both the number and area of mineralized bone nodules at low concentrations (1 and 10 μM), but decreased both at higher concentrations (25 and 50 μM). These findings demonstrate that zinc has biphasic effects on the differentiation and mineralization of human osteoblast-like cells.

Characterisation of dietary fibre components in cereals and legumes used in Serbian diet

The typical Serbian diet is characterised by high intake of cereal products and also legumes are often used. The content of total fibre as well as certain fibre fractions was determined in cereals, cereal products, and cooked legumes. The content of total fibre in cooked cereals and cereal products ranged from 2.5 to 20.8 g/100 g, and in cooked legumes from 14.0 to 24.5 g/100 g (on dry matter basis). Distribution of analysed fibre fractions and their quantities differed significantly depending on food groups. Fructans and arabinoxylans were the most significant fibre fractions in rye flakes, and β-glucan in oat flakes, cellulose and resistant starch were present in significant amounts in peas and kidney beans. When the size of regular food portions was taken into consideration, the best sources of total dietary fibre were peas and kidney beans (more than 11 g/serving). The same foods were the best sources of cellulose (4.98 and 3.56 g/serving) and resistant starch (3.90 and 2.83 g/serving). High intake of arabinoxylans and fructans could be accomplished with cooked wheat (3.20 g and 1.60 g/serving, respectively). Oat (1.39 g/serving) and barley flakes (1.30 g/serving) can be recommended as the best sources of β-glucan.

Dietary fiber intake of adolescents living in a boarding school in north-eastern part of Serbia: comparison of analyzed and calculated values

The total fiber intake in the adolescent population living in a boarding school was calculated using weighted food records and food composition tables. Total, insoluble, and soluble fiber daily intakes were also analyzed using the enzymatic-gravimetric method. The results were used to estimate the applicability of the calculation method to the Serbian diet pattern. The calculated total fiber daily intake was 28.8±10.86 g/d in winter and 32.6±13.68 g/d in summer season. Analyzed intakes of soluble fiber, insoluble fiber, and total fiber in the winter season were 4.2±2.14 g/day, 29.7±12.11 g/day, and 33.65±11.374 g/day, respectively. In summer the season daily intakes were 3.4±1.41 g/day for soluble fiber, 40.6±16.65 g/day for insoluble fiber, and 43.57±17.021 g/day for total fiber. The noticed differences for insoluble and soluble fibers between seasons were significant. The calculation method consistently gave lower values, both in winter and summer samples, in comparison with the enzymatic-gravimetric method, and the difference was on average −20.5% (P <0.05).

Effect of dietary zinc on the levels and distribution of fatty acids and vitamin A in blood plasma chylomicrons

The aim of this work was to explore the effects of a low- and high-zinc diet and vitamin A on the distribution of fatty acids in chylomicrons. Mongolian Gerbils were fed a basal diet (for 3 wk) containing 8 or 38 mg zinc/kg of feed (low-zinc group [termed LZ group] and saturated zinc group [termed SZ group], respectively). The following day, the animals were given sunflower oil containing 50 nmol vitamin A. The results showed that the concentration of zinc in blood plasma was similar in both groups. The amount of plasma chylomicrons was lower in the LZ group than in the SZ group (p<0.001). The concentration of retinol in blood plasma was lower in the LZ group than in the SZ group (p<0.01). However, the results demonstrated an increase in the blood plasma retinol concentration in the LZ group compared to the SZ group when calculated per milligram of plasma chylomicrons (p<0.01). In plasma chylomicrons, fatty acids corresponding to 16∶0, 16∶1, 17∶0, 17∶1, 18∶0, 18∶1, 18∶2, 18∶3, 20∶0, 21∶0, and 20∶4 were detected. The fatty acid distribution was similar in both groups. There was no major difference in the concentration of fatty acids in plasma chylomicrons between both experimental groups, except for 20∶4 (a lower amount was found in the SZ group). Our results show that dietary zinc influences both the amount of chylomicrons in blood plasma and the concentrations of retinol and arachidonic acid in chylomicrons.

Functional Foods and Their Role in the Improvement of Health Status

Funkcionalna Hrana - Uloga U Unapređenju Zdravlja Funkcionalna hrana je hrana koja ima povoljan uticaj na ljudsko zdravlje mimo uobičajenih nutritivnih funkcija. Biološki aktivna jedinjenja su nosioci povoljnog dejstva funkcionalne hrane. Brojni naučni dokazi govore u prilog tome da je ishrana bogata pojedinim namirnicama (kao što su to na primer voće i povrće) direktno u vezi sa smanjenim rizikom od hroničnih, nezaraznih bolesti, tako da se na tim saznanjima razvio koncept funkcionalne hrane. Otkrivaju se funkcionalne osobine tradicionalnih namirnica, ali se dizajniraju i nove funkcionalne namirnice. Uobičajene izjave koje prate tu vrstu namirnica mogu se svrstati u dve kategorije: (1) izjave o odnosu strukture i funkcije (engl. Structure and function claims) moraju da budu istinite i da ne dovode u zabludu potrošača. Te izjave ne moraju da budu odobrene od strane FDA; (2) zdravstvene izjave (engl. Health claims ili disease-specific claims) moraju da budu autorizovane od strane FDA i da poseduju značajnu naučnu potvrdu (Hillovi kriterijumi). Neophodno je rangiranje dokaza različitih tipova studija koje podržavaju zdravstvenu izjavu. Veliki broj biološki aktivnih jedinjenja su nestabilna tokom tretmana i čuvanja. Ona podležu mnogobrojnim hemijskim reakcijama, kao što su to oksidacija, hidroliza, termička degradacija i Maillardova reakcija, što rezultira smanjenjem bioiskoristljivosti. Povoljan efekat biološki aktivnih jedinjenja direktno zavisi od primenjenog tretmana. Functional Foods and Their Role in the Improvement of Health Status Functional foods are foods that may provide a health benefit beyond basic nutrition. Numerous scientifically proven pieces of evidence in many epidemiological studies indicate that nutrition abundant in certain foods (e.g. fruits and vegetables) is directly correlated with a decreased risk of degenerative diseases. Biologically active compounds in functional foods may impart health benefits or desirable physiological effects. Functional attributes of many traditional foods are being discovered, while new food products are being developed with beneficial components. These results are closely related to nutritions potentials in preventing chronic diseases. Based on these facts the concept of functional foods has been developed. Rigorous scientific investigation has to confirm the positive physiological effects of these compounds upon health. Labeling claims that are used on functional foods are of two types: (1) structure and function claims, which describe effects on normal functioning of the body, but not claims that the food can treat, diagnose, prevent, or cure a disease (claims such as >promotes regularity<, >helps maintain cardiovascular health<, and >supports the immune system< fit into this category); and (2) disease-risk reduction claims, which imply a relationship between dietary components and a disease or health condition. Structure and function claims do not require preapproval by the FDA, and they require much less stringent scientific consensus than disease-risk reduction claims. Many biologically active compounds are unstable during treatments and storage. They undergo many common chemical reactions such as oxidation, hydrolysis, thermal degradation and Maillard reaction, contributing to the lowering of bioavailability. Anyhow, beneficial effect of bioactive compounds depends directly on the applied treatment in the production of foods.

Impact of Selenium Addition to Animal Feeds on Human Selenium Status in Serbia

Research conducted during the 1980s demonstrated Se deficiency in humans. Increased inclusion of selenium in animal feeds started from the year 2000 onwards. The aim of this study was to estimate the effects of selenium inclusion in animal feeds on human selenium status and dietary habits of the Serbian population related to food of animal origin. Plasma selenium concentration in healthy adult volunteers, including residents of one of the regions with the lowest (Eastern Serbia, n = 60) and of one of the regions with the highest Se serum levels reported in the past (Belgrade, n = 82), was determined by hydride generation atomic absorption spectrometry. Multivariate analysis was employed to determine the correlation between Se plasma levels and dietary intake data derived from food frequency questionnaires and laboratory tests. The mean plasma Se level of the participants was 84.3 ± 15.9 μg/L (range: 47.3–132.1 μg/L), while 46% of participants had plasma Se levels lower than 80 μg/L. Frequency of meat, egg, and fish consumption was significantly correlated with plasma selenium level (r = 0.437, p = 0.000). Selenium addition to animal feed in the quantity of 0.14 mg/kg contributed to the improvement of human plasma selenium levels by approximately 30 μg/L.