Researchers from the University of Bonn conducted a trial investigating the metabolic effects of an intensive oat-based diet on 32 adults exhibiting characteristics of metabolic syndrome, including high blood pressure and elevated lipid levels. The participants consumed 300 grams of boiled oatmeal three times daily for two days, amounting to roughly half their usual caloric intake, while a control group followed a general calorie-reduced diet.
According to Junior Professor Marie-Christine Simon, the results for the oat group were substantially more pronounced than the control group, showing a 10% drop in LDL cholesterol, a figure described as substantial though not comparable to modern pharmaceutical interventions. Participants in the oat group also averaged two kilograms of weight loss and experienced slight decreases in blood pressure.
Lead author Linda Klümpen reported that the mechanism appears linked to gut microbiome changes, noting that oatmeal consumption increased specific beneficial bacteria populations. These microbes metabolize the oats, producing compounds such as ferulic acid, which animal studies have previously linked to positive cholesterol metabolism.
Furthermore, the bacteria actively consumed the amino acid histidine, which the human body typically converts into a molecule suspected of promoting insulin resistance, a hallmark of diabetes. This dual action—producing beneficial compounds while reducing precursors to insulin resistance—highlights the complex interaction between diet and the gut flora.
Interestingly, the study contrasted this two-day intensive approach with a six-week trial consuming a more moderate 80 grams of oats daily without caloric restriction, which yielded only minor effects. This suggests that the concentration of the oat intake, coupled with reduced overall calories, is critical for achieving significant cardiovascular benefits.
The positive effects from the intense two-day protocol were reportedly still observable six weeks later, leading Professor Simon to suggest that short, repeated oat-based interventions could be a well-tolerated method for maintaining healthy cholesterol levels and potentially preventing diabetes.
Both dietary interventions were structured as randomized controlled trials, though blinding the participants on diet composition was not feasible, according to the report published by the researchers, whose work was supported by several German federal and industry bodies.
