Short-term intake of fiber-rich oat bran but not spelt bran lowers bacterial endotoxin levels and improved health parameters in healthy women

Diets low in dietary fiber have repeatedly been shown to be associated with higher risks for various non-communicable chronic diseases (NCCDs). Here, we assessed in a cross-over designed study if fiber rich oat bran rich and spelt bran rich flake mixes (~11.7g total fiber), respectively, are suitable to increase general fiber intake in healthy women and if this enhancement of dietary fiber intake impacts intestinal microbiota composition, markers of intestinal barrier function, and general health parameters. Dietary intake was determined and blood and stool samples were collected along with a general health assessment before and at the end of each one-week intervention from 10 female, normal weight participants (aged 31.9 ± 2.6 years). The intake of the eitherboth flake mixes was associated with a significant increase in dietary fiber intake during the interventions while overall dietary pattern and macronutrient intake remained almost unchanged. After the spelt bran intervention only blood pressure was significantly lower whereas after the intake of the oat bran rich flakes LDL- and total cholesterol levels as well as alanine transaminase (ALT) and aspartate transaminase (AST) activities in blood were also significantly lower. The incorporation of the oat bran flake mix in the diet resulted in a significant decrease of bacterial endotoxin in blood but no change in intestinal microbiota composition whereas effects alike were not found after the intake of spelt bran. Taken together, results of our study suggest that fiber rich flake mixes may be a suitable measure to increase overall dietary fiber intake and thereby improve general health but that health effects and mechanisms underlying may differ between different dietary fibers.