In vitro availability of calcium from sources of cellulose, methylcellulose, and psyllium

Certain types of dietary fibres may decrease the amount of dietary calcium available for absorption. The objective of this study was to determine the in vitro calcium availability from sources of cellulose, methylcellulose, and psyllium, such as cereals, fibre supplements, and purified fibres. Total dietary fibre, soluble and insoluble dietary fibre, acid detergent fibre, neutral detergent fibre, cellulose, hemicellulose, lignin, protein, uronic acid, phytate, water holding capacity, and total endogenous calcium content were determined. Results from the chemical analyses of the fibre sources varied significantly. Free endogenous calcium, at pH 3-8, was determined via gel filtration. Calcium was added to each fibre source and free exogenous calcium was determined via gel filtration at pH 1 and pH 8. The analysis of variance procedure was used to determine differences in binding capacities of the fibres. There was virtually no binding of exogenous calcium by sources of cellulose, methylcellulose, or psyllium. (C) 2002 Elsevier Science Ltd. All rights reserved.