Epsilon Open Archive

Abstract

Whole grains are rich in dietary fibre and bioactive compounds and have consistently been associated to improved health and lower mortality. Whole-grain rye is rich in fermentable fibre and lignans, that are converted to enterodiol and enterolactone by the gut microbiota. Enterolactone has been studied widely for several suggested beneficial health properties. In this thesis, the role of whole grains and lignans in cardio-metabolic health and mortality from type 2 diabetes and prostate cancer was studied.

Whole-grain rye and lignans did not affect glucose response assessed by an oral glucose tolerance test in men with metabolic syndrome after 8 wk intervention. Whole-grain rye improved lipid profile by lowering LDL-cholesterol compared to whole-grain wheat, whereas high-dose lignan supplementation had no effect on any of the investigated cardio-metabolic outcomes. Baseline microbiota enterotype appeared to explain some of the difference in response to treatments. Lipid profile was improved in the Prevotella enterotype by whole-grain rye diet and in the Bacteroides enterotype by whole-grain wheat diet. Lifestyle intervention with high intake of whole-grain rye and physical activity was feasible to implement in a group of men with non-aggressive prostate cancer. However, a full-scale trial is needed to investigate the potential of whole-grain rye in prostate cancer progression. Lastly, plasma enterolactone was investigated in two observational studies based on data from the population-based Diet, Cancer and Health cohort. Enterolactone concentrations were inversely associated with mortality among persons with type 2 diabetes, whereas no association with mortality was observed in men with prostate cancer.

Overall, the findings from the this thesis highlights that whole-grain rye has beneficial health properties related to lipid profile, that long-term dietary interventions with high intake of whole-grains are feasible among middle-aged men with metabolic syndrome or prostate cancer, and that plasma enterolactone is associated with lower mortality among persons with type 2 diabetes. Furthermore, the finding of no association between enterolactone and prostate cancer mortality contributes to the existing evidence from observational studies that does not support the findings of a protective role from cell, animal and a few human interventions.