|Nielsen, Forrest - Frosty|
Submitted to: Biological Trace Element Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2007
Publication Date: 2/10/2008
Publication URL: http://handle.nal.usda.gov/10113/34526
Citation: Turner, K.K., Nielsen, B.D., O'Connor-Robison, C.I., Nielsen, F.H., Orth, M.W. 2008. Tissue response to a supplement high in aluminum and silicon. Biological Trace Element Research. 121(2):134-148 Interpretive Summary: Silicon has been long suspected to be a beneficial, if not essential, element. In addition, supra nutritional amounts of silicon have been shown to have beneficial effects in higher animals. Supra nutritional dietary silicon has been shown to counteract aluminum toxicity and enhance copper and magnesium utilization or absorption, and may have positive effects on bone and cardiovascular health. Sodium zeolite A is a compound that is broken down to aluminum and the silicon compound orthosilicic acid. Sodium zeolite A supplementation has been shown to have beneficial effects on disorders of calcium and magnesium metabolism in adult dairy cows and decrease skeletal-related injury in race horses. Thus, a study was performed to determine whether sodium zeolite A supplemented (providing supra-nutritional amounts of silicon) to dairy bull calves (not silicon-deprived) was beneficial to mineral metabolism. The sodium zeolite A supplementation (0.05% of body weight) increased silicon concentrations in the aorta, spleen, lung, muscle, and kidney. The sodium zeolite A supplementation increased aluminum retention with every tissue (adrenal, aorta, heart, kidney, liver, lung, muscle, pancreas, spleen, tendon, and trachea) examined showing an increased aluminum concentration. The increase in tissue silicon and aluminum were associated with some significant changes in the concentrations of other minerals. Calcium concentrations were increased in aorta, liver, muscle, and tendon; phosphorus concentrations were increased in aorta, but decreased in plasma; magnesium concentrations were increased in aorta, heart, kidney, liver, and pancreas, but decreased in plasma; and iron concentrations were decreased in kidney and liver. These changes, especially the increases in aorta and tendon calcium, and the decreases in kidney and liver iron, may not be beneficial. These could be indicative of aluminum antagonism of iron metabolism, and aluminum retention causing aortic calcification. Aluminum retention may have masked any beneficial effects of silicon. Thus, to obtain a better understanding about the possible beneficial effects of supra-nutritional silicon, a source not containing aluminum may be necessary. Furthermore, the study suggests that sodium zeolite A supplementation is not a practice that is useful in improving mineral metabolism in healthy dairy calves. Instead, high sodium zeolite A supplementation may be of concern because it could result in aluminum accumulation in tissue that induce changes that could be construed as detrimental to iron metabolism and calcium utilization.
Technical Abstract: The objective was to determine the effects of sodium zeolite A (SZA) on mineral metabolism and tissue mineral composition in calves. Twenty calves were placed on study at three days of age, and were placed into one of two groups: SS, which received 0.05% BW SZA added to their milk replacer and CO, which received only milk replacer. Blood samples were taken on d 0, 30, and 60 for mineral analysis. Urine and feces were collected on d 30 for mineral metabolism and, on d 60, the calves were euthanized and samples were taken from numerous organs for mineral analyses. Aluminum retention was increased in the SS calves (p=0.001). Silicon concentrations were increased in the aorta, spleen, lung, muscle, and kidney of the SS calves, and aluminum was increased in all SS tissues (p<0.05). Calcium concentrations were increased in aorta, liver, muscle, and tendon; phosphorus concentrations were increased in aorta, but decreased in plasma; magnesium concentrations were increased in aorta, heart, kidney, liver, and pancreas, but decreased in plasma; and iron concentrations were decreased in kidney and liver (p<0.05). The accumulation of tissue aluminum and therefore potential adverse consequences may preclude any benefits of using SZA as a dietary supplement.