Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 10

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  iodine content
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
A simple spectrophotometric method for the determination of total iodine content in foods by modification of Sveikina procedure, based on the works of Moxon and Dixon, is reported. The modified method had about 100-fold higher sensitivity in comparison to the above mentioned methods. The method detection limit (MDL) was 0.01 ng per 100 g of food and a mean recovery test of 92%. This method was used for the analyses of total iodine content in different food products
Justus von Liebig (1842) introduced soil fertilization with nitrogen and improved the importation of Chile saltpetre, which contained iodine up to 1 g/kg and increased the iodine content of the food. World War I stopped nitrogen fertilization in Germany, resulting in iodine deficiency. After World War II, East Germany imported fish meal from Peru, which satisfies the iodine requirement of farm animals and - via milk and eggs - that of man. After the end of fish meal importation, iodine deficiency reappeared. The iodine contents of most rocks vary from 0.01 - 0.50 mg/kg in the ultramafic rocks to 2 - 6 mg/kg in shales. Worldwide, the iodine concentration in soils varies between < 0.1 and 10 mg I/kg dry matter (DM), with an average of 2.8 mg/kg DM. Ocean water is rich in iodine, which gets back to the continents with the rain as diiodine methane, 8-10 µg/L near the coast and < 1 µg/L in the European Alps. The vegetation of the Holocene riverside soils is relatively rich in iodine, whereas that growing on Triassic sediments is extremely iodine-poor. Iodine is delivered to the food chain of animals and man through contamination of feeds and foods. The iodine concentration of the flora decreases with increasing age of the annual plants. Flowers, fruits, seeds, pulps and all starch- and sugar-rich parts of plants are poor in iodine. All baked goods contain low iodine amounts.
The iodine intake by 7 ad least respectively omnivorous and ovolactovegetarian women and men was examined in 21 test teams in Central Europe and Mexico by the duplicate portion technique over 7 successive days. Women in Germany presently consume > lOOµg, men > 120µg I/day on average, or 1.3 and 1.5 µg/kg body weight/day respectively. In Mexico, iodine intakes by women and men amount to 150 and 200 µg I/day, or 2.5 and 2.6 µg/kg body weight and day, respectively. Although, on average, the normative iodine requirement of adults is met (1 µg, recommendation 2 µg/kg body weight and day), 25% of German adults take in less than 100 and 120 µg I/day, resp. Iodine consumption in summer is 40% lower than in winter. It increases by 30% with rising age (20 - 69 years) and by 45% with increasing body weight. In the endemic iodine- and selenium-deficient region of Central Europe, where iodine intake and serum T4 status were normalized by iodinated salt, it was not possible to normalize the free T3 level in the blood serum. The GSH-Px levels of women’s blood serum (170 U/L) were normal. Supplementation of 50 µg Se and 100 µg I/day normalized the serum-free T3 level. A normalization of iodine metabolism is only given if both the iodine and selenium requirements are met. An increase in the incidence of hyperthyroidism worldwide has been described after iodine supplementation in iodine deficiency regions. The intake by adults is limited to 7 µg/kg body weight. The main excretory routes for iodine are the kidneys and the breast, which compete with the thyroid for plasma iodine. Urine and milk are good indicators of the iodine status and intake, if fecal iodine excretion of humans (about 10 - 80 µg/day) is taken into consideration. On average, omnivores and vegetarians excrete 76 to 87% of the consumed iodine renally and 15 to 24% fecally. Their apparent iodine absorption rate is 83%, on average, and their iodine balance is 2 to 27%. Breastfeeding women without iodine-supplementation excrete 48% of their iodine intake with the milk, 45% with urine and 7% with feces. After iodine supplementation of the mineral mixtures fed to animals and of salt for humans, iodine concentrations in cows and breast milk increased from 10 µg/L to > 100 µg/L. At the start of the new millennium, the annual world production of iodine amounted to 19,600 t, which is partly used for iodine supplementation of animals and man.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.