Dietary Fiber Supplementation With Wheat Dextrin Does Not Inhibit Calcium and Magnesium Absorption in Pre and Post Menopausal Women: 2010 Presidential Poster

Abstract

Purpose: Previous studies have indicated that some dietary fibers may interfere with calcium absorption and few studies have been done on fiber's effect on magnesium absorption. Some dietary fibers with high viscosity may interfere with the absorption of drugs and vitamins. Wheat dextrin is a soluble fiber used as a dietary supplement. The purpose of this study was to examine the effect of chronic wheat dextrin intake on calcium and magnesium absorption in a placebo controlled, randomized crossover clinical trial. Methods: Study subjects consisted of 20 premenopausal (age 42.6±5.0 yrs) and 20 postmenopausal Caucasian women (age 57.0±7.6 yrs). Each of the subjects consumed 5 grams of wheat dextrin or placebo in the form of cookies, three times daily for 2 weeks prior to measuring their calcium and magnesium absorption. On the day of testing, a standardized breakfast containing 300 mg calcium (in calcium fortified orange juice) extrinsically labeled with 45Ca and 26Mg was consumed by the subjects. Blood samples were obtained for 45Ca at 0, 1, 3, 5, 7, and 9 hours. Urine samples were obtained for 2 subsequent nights for 26Mg measurement. 45Calcium was measured by atomic absorption spectrophotometer and 26Mg isotope ratios were analyzed using inductively coupled plasma mass spectrometry. Area under the curve to 9 hours AUC9) was calculated for increment of serum calcium and for 45Calcium specific activity. The enrichment of the 26Mg isotope was determined as the “percent excess” of 26Mg above the naturally occurring 26Mg/24Mg ratio. Results: In the study population the mean (±SD) AUC9 for increment in serum calcium was 1.57 (±1.29) for wheat dextrin and 1.61 (±1.25) for placebo (p=0.82) indicating no effect on calcium absorption with wheat dextrin treatment. The mean (±SD) AUC9 measured from the 45Ca specific activity was 0.81 (± 0.21) for wheat dextrin and was 0.82 (±0.22) for placebo (p=0.34) demonstrating no effect on 45Ca absorption. There was good agreement between pharmacokinetic and tracer methods used in determining calcium absorption (R2=0.6231). The percent excess of 26Mg/24Mg was 7.8% (SD±2.1%) for wheat dextrin and was 7.9% (SD±2.6%) for placebo (p=0.827) demonstrating no effect on magnesium absorption. Conclusion: The study demonstrates that chronic supplementation with wheat dextrin for the increase of dietary fiber does not inhibit calcium or magnesium absorption from the gastrointestinal tract in both pre and postmenopausal women. Disclosure: Ashok Hospattankar is an employee of Novartis Consumer Health, Inc. Laura Armas has grant/research support from Novartis Consumer Health, Inc. This research was supported by an industry grant from Novartis Consumer Health, Inc.