Xiujuan Jia

Document Type

Dissertation - University Access Only

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Chemistry and Biochemistry


Using Sprague Dawley weanling rats as an experimental model, the bioavailability of different silicon sources, the interactions among silicon, copper, zinc, iron and ascorbic acid, the subsequent effects of these interactions, and the pH dependence of the silicon-iron interaction were studied. Of the three commonly used silicon sources, sodium silicate, sodium zeolite A and tetraethylorthosilicate, the inherent toxic aluminum content of sodium zeolite A makes it less than an ideal silicon source. No major difference was observed for the bioavailability of silicon from sodium silicate and tetraethylorthosilicate. Neither the previously reported silicon-zinc antagonism nor the silicon growth promoting effect were observed. A new role for silicon in mineral metabolism is defined by this research, i.e., silicon promotion of iron absorption and transportation. Compared to 35 ppm iron, 187 ppm iron lowered zinc and copper absorption, lowered intestinal metallothionein, induced copper deficiency and, subsequently, impaired iron absorption and utilization. The high-iron induced copper deficiency imposed an increased risk for the development of vascular problems, evidenced as cardiac enlargement, and lowered blood packed cell volume and hemoglobin concentration. The 500 ppm silicon, supplemented in the form of tetraethylorthosilicate, appeared to facilitate iron absorption and transportation. Lowered rat growth associated with 500 ppm of dietary silicon is believed to be due to the increased availability of iron and the subsequent iron x copper and iron x zinc antagonisms. The supplementation of 900 ppm ascorbic acid inhibited the utilization of iron, therefore countering the effect of silicon. Further studies showed that the silicon x iron interaction was pH dependent. The promotion effect of silicon on iron absorption and transportation was detected only in rats fed acidic (ammonium chloride supplemented) and neutral (unsupplemented) diets but not in those fed basic ( sodium bicarbonate supplemented) diets.

Library of Congress Subject Headings

Rats -- Nutrition Silicon in the body Trace elements in animal nutrition



Number of Pages



South Dakota State University