Unfermented High-Fiber Rye Crispbread Increases Plasma HDL and Reduces Hepatic Lipids Compared to Refined Wheat in Rats Fed a High-Fat Diet

Fiber-rich rye foods reduced body weight in overweight or obese individuals compared to refined wheat, though the underlying mechanisms remain unclear. This study compared the effects of whole grain fermented and unfermented rye with refined wheat crispbread on body weight and lipid metabolism in rats. Exploratory outcomes included adiposity, appetite biomarkers, glucose homeostasis, colon inflammation, integrity, and permeability. Sprague Dawley rats (n = 54) were acclimatized (2 weeks) and randomized to control (n = 9) or high-fat diets (n = 45) for 16 weeks. Animals in the high-fat group were randomized to continue the high-fat (n = 9) or receive a standard diet alone (n = 9) or the standard diet with either refined wheat crispbread (n = 9), fermented rye crispbread (n = 9), or unfermented rye crispbread (n = 9) for 8 weeks. A high-fat diet did not affect final body weight, glucose homeostasis, and colon inflammation, but increased energy intake, adiposity, and leptin compared to control, and hepatic triacylglycerols compared to all other groups. Unfermented rye crispbread increased plasma HDL-cholesterol and reduced hepatic triacylglycerols and cholesterol compared to refined wheat, despite the absence of effects on obesity and glycemic control. No differences were observed between fermented and unfermented rye. Unfermented whole-grain rye crispbread may potentially exhibit favorable lipid-modulating effects.