Effects of meal frequency and high-fibre rye-bread diet on glucose and lipid metabolism and ileal excretion of energy and sterols in ileostomy subjects

Objective: To investigate the effect of a rye, high-fibre diet (HFD) vs a wheat, low-fibre diet (LFD), meal frequency, nibbling ( Nib, seven times a day) or ordinary (Ord, three times a day), and their combined effects on blood glucose, insulin, lipids, urinary C-peptide and ileal excretion of energy, cholesterol and bile acids in humans. Design: LFD period with Nib or Ord meal frequency followed by an HFD diet with Nib or Ord meal frequency in randomized, crossover design. Setting: Outpatients of ileostomy volunteers were called for an investigation in research word. Subjects: A total of 10 subjects ( two female subjects, age 34 and 51 y; eight males, mean age 54.4 y, range 43 - 65 y) participated in the experiment. All subjects were proctocolectomized for ulcerative colitis ( mean 16.0 y, range 8 - 29 y before the study). Intervention: In total, 10 ileostomy subjects started with LFD for 2 weeks, the first week on either Nib ( five subjects) or Ord ( five subjects) and the second week on the other meal frequencies, in a crossover design, followed by a wash-out week, and continued with HFD period for 2 weeks in the same meal frequency manner. All foods consumed in both Nib or Ord regimens were identical and a high-fibre rye bread was used in the HFD period and a low-fibre wheat bread in the LFD period. Main outcome measures: Day-profiles of blood glucose, insulin and lipids, blood lipids before and after dietary intervention, and excretion of steroids in the effluents and C-peptide in the urine. Results: During the Nib regimen, plasma glucose and insulin peaks were lower at the end of the day with HFD compared with LFD. Urinary C-peptide excretion was significantly higher in the day-time on LFD compared with HFD (LFD-Ord vs HFD-Ord, P<0.01; LFD-Nib vs HFD-Nib, P<0.01). Plasma free-cholesterol, total cholesterol, triglycerides and phospholipids were significantly higher (P<0.05) after LFD than after HFD with the Nib regimen. A higher excretion of energy (P<0.05) and chenodeoxycholic acid (P<0.05) were observed with HFD compared with LFD regardless of meal frequency. A higher daily excretion of cholic acid, total bile acids, cholesterol, net cholesterol and net sterols ( P<0.05) was observed on HFD compared with LFD with the Nib regimen. Conclusions: An HFD decreased insulin secretion measured as a decreased excretion of C-peptide in urine and as decreased plasma insulin peaks at the end of the day during a Nib regimen. The smoother glycaemic responses at the end of the day during a Nib regimen may be a consequence of a second meal phenomenon, possibly related to the nature of dietary fibre complex. Sponsorship: This study was supported by grants from the Swedish Council of Forestry and Agricultural Research (SJFR).