Objective: To compare if postprandial glucose and insulin responses to wholekernel rye bread are lower than to wheat bread, and to see if these responses to two types of rye breads are different. To explore starch digestion in more detail, rate of starch hydrolysis of same breads was measured in vitro. Design: Subjects were given test breads (43 ± 61 g available carbohydrates by analysis) with standardized breakfast in a random order after a fast. Eight postprandial blood samples were collected during the following three hours. Rate of starch hydrolysis was determined by an in vitro enzymatic hydrolysis method. Subjects: 10 men and 10 women, aged 32 AE 3 and 27 AE 5 y, BMI 24.5 AE 2.2 and 20.3 AE 1.1 kgam 2 , respectively, all had normal glucose tolerance. Results: Plasma insulin response to wholekernel rye bread was lower than to wheat bread (45 min P 0.025, 60 min P 0.002, 90 min P 0.0004, 120 min P 0.050, 150 min P 0.033), but there was no difference in glucose responses. In comparison of two types of rye breads, glucose response to wholemeal rye bread at 150 and 180 min was higher (P 0.018 and P 0.041, respectively) and insulin response at 60 min was lower (P 0.025) than those to wholemeal rye crispbread. Total sugar pro®les in vitro were similar for all breads. When free reducing sugars were subtracted, starch in wholekernel and wholemeal rye breads appeared to be hydrolysed slower than starch in wholemeal rye crispbread and wheat bread. Conclusions: Wholekernel rye bread produces lower postprandial insulin response than wheat bread, but there is no difference in glucose response. The latter is in accordance with in vitro results. Postprandial glucose and insulin may also be affected by type of rye bread. Characteristics of different types of rye breads must be further investigated to develop health properties of rye breads. Sponsorship:

The objective of this study was to determine the hypocholesterolemic effects of whole meal rye and white wheat breads in healthy humans with elevated serum cholesterol concentrations, and the changes in plasma glucose and insulin concentrations during rye and wheat bread periods. The subjects were 18 men and 22 women with baseline serum cholesterol concentration of 6.4+/-0.2 mmol/L. The study design was a 2x4-wk crossover trial during which each subject randomly consumed rye and wheat breads (20% of daily energy) as part of their usual diet for 4 wk. The bread periods were separated by a 4-wk washout period. Blood samples (after fasting) were collected on two consecutive days at the beginning and end of the bread periods. Serum total cholesterol decreased by 8% (P = 0.002) in men but was not significantly altered in women during the rye bread period. The wheat bread period did not affect any of the variables studied. Analysis of the serum lipids in tertiles of rye bread consumption confirmed the reduction in total cholesterol (P = 0.048) in men and revealed the reduction in LDL cholesterol (P = 0.032); both were dependent on the amount of rye bread consumed (-2, -14 and -10% in total cholesterol and 0, -12 and -12% in LDL cholesterol). Neither rye nor wheat bread influenced the concentrations of glucose and insulin. In conclusion, rye bread is effective in reducing serum total and LDL cholesterol concentrations in men with elevated serum cholesterol. Good compliance with consuming a relatively large amount of rye bread in the usual diet indicates that rye bread offers a practical dietary means of reducing serum cholesterol in men.

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