Effect of a high-fiber diet compared with a moderate-fiber diet on calcium and other mineral balances in subjects with type 2 diabetes.
OBJECTIVE
High levels of dietary fiber, especially soluble fiber, are recommended to lower serum cholesterol levels and improve glycemic control in patients with type 2 diabetes. It is not clear, however, how high levels of fiber affect mineral balance.


METHODS
In a randomized crossover study, 13 patients with type 2 diabetes were fed a high-fiber (50 g total and 25 g soluble fiber) and a moderate-fiber (24 g total and 8 g soluble fiber) diet of the same energy, macronutrient, calcium, magnesium, and phosphorus content for 6 weeks each. Intestinal calcium absorption was determined by fecal recovery of (47)Ca. Stool weight and mineral content were assessed during 3 days, and 24-h urinary mineral content and serum chemistry were assessed over 5 days at the end of each phase. The results were compared by repeated-measures ANOVA.


RESULTS
Compared with the moderate-fiber diet, the high-fiber diet increased stool weight (165 +/- 53 vs. 216 +/- 63 g/day, P = 0.02) and reduced 24-h urinary calcium (3.3 +/- 1.7 vs. 2.4 +/- 1.2 mmol/day, P = 0.003) and phosphorus (29.2 +/- 5.5 vs. 26.0 +/- 3.2 mmol/day, P = 0.003) excretion and serum calcium concentration (2.33 +/- 0.06 vs. 2.29 +/- 0.07 mmol/l, P = 0.04). Calcium absorption, stool calcium, magnesium, and phosphorus content and serum phosphorus concentration were not significantly different with the two diets.


CONCLUSIONS
A high-fiber diet rich in soluble fiber has a small impact on calcium and phosphorus balance in subjects with type 2 diabetes. It may be prudent to ensure adequate intake of calcium and other minerals in individuals consuming a high-fiber diet.
Shah
Meena
M
Division of Nutrition and Metabolic Diseases, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA.
Chandalia
Manisha
M
Adams-Huet
Beverley
B
Brinkley
Linda J
LJ
Sakhaee
Khashayar
K
Grundy
Scott M
SM
Garg
Abhimanyu
A
D001774:Blood Chemical Analysis; D002118:Calcium / Q000097:blood*; D002136:Calcium, Dietary / Q000378:metabolism; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D004032:Diet / Q000706:statistics & numerical data*; D004043:Dietary Fiber; D006801:Humans; D007408:Intestinal Absorption; D008903:Minerals / Q000097:blood / Q000652:urine; D010758:Phosphorus / Q000097:blood; D016482:Urinalysis
D002136:Calcium, Dietary; D004043:Dietary Fiber; D008903:Minerals; D010758:Phosphorus; D002118:Calcium