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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #77380
Title: BONE DENSITY AND TISSUE LEAD ACCRETION IN GROWING RATS FED LOW HIGH CALCIUM WITH OR WITHOUT SUPPLEMENTAL CLINOPTILOLITE.

Author
item POND, WILSON - USDA/ARS/CNRC
item KROOK, L - CORNELL UNIVERSITY
item SU, DAI-RONG - BAYLOR COLL OF MEDICINE
item SCHOKNECHT, P - RUTGERS UNIVERSITY

Submitted to: Bulletin of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: We wanted to determine whether adding calcium and/or a mineral called clinoptilolite would affect the growth, tissue uptake or bone of growing rats fed diets containing poisonous (toxic) amounts of lead. Our interest stemmed from the fact that the toxicity of lead in animals and human beings is well known, and a previous study showing that the amount of lead in pigs' liver and kidney was greatly reduced by adding clinoptilolite to diets containing lead. We fed rats a fortified milk replacer diet containing low or high calcium, with and without clinoptilolite. The mineral did not protect against tissues' lead uptake in the rats, which may be due to a species difference. However, the mineral improved bone tissue accretion in the femur of rats fed the low-calcium diet, which suggests improved absorption of calcium. That has important implications for food animal production and environmental quality in regard to the usage of calcium provided in the diet. The high-calcium diet offered protection against lead buildup in tissue. These findings contribute to our knowledge about the potentially protective effects of certain types of diets consumed by growing mammals.

Technical Abstract: The cation-exchange and adsorption properties of clinoptilolite suggest its possible role in reducing tissues uptake of ingested lead by animals. Evidence supporting this role was reported in growing pigs whose liver and kidney concentrations of lead were significantly reduced by the addition of 1.0% clinoptilolite to diets containing 500 or 1000 ppm of lead (Pond et al, 1993). The basal diet was a highly fortified milk-replacer containing about 1% calcium supplied by milk constituents. High dietary calcium is known to reduce tissue uptake of lead and protect the pig from the tissue pathology associated with lead ingestion (Hsu et al, 1975). The objective of this experiment was to test the hypothesis that dietary clinoptilolite and calcium levels affect the growth, tissue uptake and bone morphology of growing rats fed diets containing toxic levels of lead. Seventy-two male weanling Sprague-Dawley rats weighing 45+/-5 g were assigned within 4 replicates based on litter to 18 groups of 4 animals each in a 2x3x3 factorial arrangement of dietary treatments (2 levels of Ca (0.29 and 0.96%), 3 levels of Pb (0, 200 and 600 ppm), and 3 levels of clinoptilolite (0, 1.5 and 3.0%)). Clinoptilolite did not reduce Pb uptake by liver and kidney, but increased bone Ca concentration in rats fed low Ca. The protective effect of dietary clinoptilolite against tissue Pb accumulation in growing pigs, but not in growing rats, may represent a species difference in response related to fundamental differences in eating behavior and digestive physiology.