Effect of dietary rhubarb stalk fiber on the bioavailability of calcium in rats.
Ground rhubarb stalk fiber containing, on a dry weight basis, 74% total dietary fiber (66% insoluble and 8% soluble) was prepared from rhubarb plants. This fiber source has been shown to have a pronounced lipid lowering effect in mice. Its high oxalic acid content may, however, be a limiting factor for its use. The present study was undertaken to determine the safe dose level of the fiber in terms of its effect on calcium bioavailability. Male weanling Sprague-Dawley rats were fed a semi-purified diet (AIN 76) for 4 weeks containing 0, 1, 3, or 5% rhubarb fiber, or pure oxalic acid equivalent to 5% rhubarb fiber. The fiber content of each diet was brought to 5% by adding cellulose, and the calcium level of all diets was the same. As the rhubarb stalk fiber content of the diet increased, a consistent trend of increasing total retention and apparent absorption of calcium was manifested. In contrast, however, cellulose, due to its increased effect on intestinal motility resulted in a decreased calcium bioavailability. Overall results suggest that an addition of rhubarb stalk powder up to the level of 5% in a diet does not have detrimental effect on calcium bioavailability.
Goel
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Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada.
Ooraikul
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Basu
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TK
D000818:Animals; D001682:Biological Availability; D002118:Calcium / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002482:Cellulose / Q000008:administration & dosage / Q000494:pharmacology; D004043:Dietary Fiber / Q000494:pharmacology*; D007408:Intestinal Absorption; D008297:Male; D010946:Plants, Medicinal; D051381:Rats; D017207:Rats, Sprague-Dawley; D012250:Rheum
D004043:Dietary Fiber; D002482:Cellulose; D002118:Calcium