High-fiber rye bread and insulin secretion and sensitivity in healthy postmenopausal women.
BACKGROUND
Fiber and whole-cereal intakes may protect against hyperinsulinemia and the risk of type 2 diabetes.


OBJECTIVE
The aim was to study whether the long-term use of high-fiber rye bread and white-wheat bread modifies glucose and insulin metabolism in healthy postmenopausal women.


METHODS
The study was a randomized crossover trial consisting of 8-wk test and 8-wk washout periods. The subjects were 20 postmenopausal women [macro x +/- SD age: 59 +/- 6.0 y; body mass index (in kg/m(2)): 27.5 +/- 2.9; baseline fasting serum cholesterol: 6.5 +/- 0.8 mmol/L], of whom 3 had impaired glucose tolerance as determined by a 2-h oral-glucose-tolerance test. The test breads were high-fiber rye and white-wheat breads, planned to make up > or =20% of energy. Fasting blood samples were collected for the measurement of plasma glucose and insulin at the beginning and at the end of both bread periods. The frequently sampled intravenous-glucose-tolerance test was performed at the run-in and at the end of both bread periods. The acute insulin response, insulin sensitivity, and glucose effectiveness were calculated.


RESULTS
The rye bread made up 23.4 +/- 4.3% and wheat bread 26.7 +/- 8.2% of total energy intake. Compared with that during the run-in period, the acute insulin response increased significantly more during the rye bread period (9.9 +/- 24.2%) than during the wheat bread period (2.8 +/- 36.3%; P = 0.047). Other measured variables did not change significantly during the study.


CONCLUSIONS
Modification of carbohydrate intake by high-fiber rye bread did not alter insulin sensitivity in postmenopausal, hypercholesterolemic women. High-fiber rye bread appears to enhance insulin secretion, possibly indicating improvement of b cell function.
Juntunen
Katri S
KS
Department of Clinical Nutrition, University of Kuopio, Kuopio, Finland. katri.juntunen@uku.fi
Laaksonen
David E
DE
Poutanen
Kaisa S
KS
Niskanen
Leo K
LK
Mykkänen
Hannu M
HM
D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D001939:Bread; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000517:prevention & control*; D004043:Dietary Fiber / Q000008:administration & dosage* / Q000378:metabolism; D005215:Fasting; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D006937:Hypercholesterolemia / Q000188:drug therapy / Q000378:metabolism; D006946:Hyperinsulinism / Q000517:prevention & control*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D017698:Postmenopause; D012307:Risk Factors; D012434:Secale
D001786:Blood Glucose; D004043:Dietary Fiber; D007328:Insulin