Whole-grain rye and wheat foods and markers of bowel health in overweight middle-aged men

Abstract

Background: Whole-grain cereal foods including rye have been identified as providing significant health benefits that do not occur when refined-cereal foods are ingested. Objectives: Foods (90 g) containing whole-grain rye flour and whole-grain wheat flour were compared with low-fiber refined-cereal foods for their effects on markers of bowel health and the metabolic markers insulin and glucose. Design: Three 4-wk interventions were undertaken in a randomized crossover design with 28 overweight men aged 40–65 y who had no history of bowel disease. Against a background intake of 14 g dietary fiber (DF), the men were fed low-fiber cereal grain foods providing 5 g DF for a total of 19 g DF/d. High-fiber wheat foods provided 18 g DF, and high-fiber rye foods provided 18 g DF, both giving a total of 32 g DF/d. Fecal samples (48-h) and fasting and postprandial blood samples were collected at the end of each period and assayed. Results: Both high-fiber rye and wheat foods increased fecal output by 33–36% (P = 0.004) and reduced fecal β-glucuronidase activity by 29% (P = 0.027). Postprandial plasma insulin was decreased by 46–49% (P = 0.0001) and postprandial plasma glucose by 16–19% (P = 0.0005). Rye foods were associated with significantly (P = 0.0001) increased plasma enterolactone (47% and 71%) and fecal butyrate (26% and 36%), relative to wheat and low-fiber options, respectively. Conclusions: High-fiber rye and wheat food consumption improved several markers of bowel and metabolic health relative to that of low-fiber food. Fiber from rye appears more effective than that from wheat in overall improvement of biomarkers of bowel health.