A remarkably short, intensive dietary change – just two days of primarily eating oatmeal – may significantly lower LDL (“bad”) cholesterol levels, according to a recent clinical trial conducted by researchers at the University of Bonn in Germany and published in Nature Communications. The study, focusing on individuals with metabolic syndrome, suggests a surprisingly effective approach to improving heart health.
Metabolic syndrome is a cluster of conditions – including excess weight, high blood pressure, elevated blood sugar, and abnormal blood lipid levels – that increase the risk of heart disease, stroke, and type 2 diabetes. Participants in the study followed a calorie-restricted diet consisting almost entirely of oatmeal for 48 hours. Compared to a control group that also reduced calories but did not consume oats, those on the oat-based plan experienced a markedly greater improvement in their cholesterol levels, an effect that remained noticeable even six weeks later.
The Impact on Cholesterol Levels
The study found that LDL cholesterol levels decreased by 10% in the group consuming primarily oatmeal. “That is a substantial reduction, although not entirely comparable to the effect of modern medications,” explains Marie-Christine Simon, junior professor at the Institute of Nutritional and Food Science at the University of Bonn. Participants also experienced an average weight loss of two kilograms and a slight reduction in blood pressure.
Lowering LDL cholesterol is crucial for cardiovascular health. Elevated LDL levels contribute to the buildup of plaque within artery walls, a process known as atherosclerosis. This narrowing of the arteries can restrict blood flow and increase the risk of heart attack or stroke if a plaque ruptures and forms a blood clot.
The Role of the Gut Microbiome
Researchers investigated the underlying mechanisms behind these beneficial effects and discovered changes in the gut microbiome. “We were able to identify that the consumption of oatmeal increased the number of certain bacteria in the gut,” says Linda Klümpen, the study’s lead author. The gut microbiome plays a vital role in how the body processes food, with microbes generating metabolic byproducts that support intestinal health and potentially influencing other organs.
Specifically, the study identified that the oats were broken down by gut bacteria, producing phenolic compounds like ferulic acid. Animal studies have previously suggested that ferulic acid positively impacts cholesterol metabolism, and the researchers believe this may also be the case in humans. The oatmeal consumption appeared to support the elimination of histidine, an amino acid that, if not processed correctly, can contribute to insulin resistance.
A Modern Echo of a Historic Therapy
The use of oats for metabolic health isn’t a new concept. In the early 20th century, German physician Carl von Noorden successfully used oats to treat patients with diabetes. “Today, effective medications are available to treat patients with diabetes,” explains Professor Simon. “this method has been almost completely overlooked in recent decades.”
The current study focused on individuals with metabolic syndrome, a precursor to diabetes, rather than diabetes itself. Researchers aimed to determine how a specialized oat-based diet would affect this population.
Study Details and Methodology
During the intensive phase of the study, participants consumed 300 grams of boiled oatmeal three times daily, supplementing it with small amounts of fruits or vegetables. A total of 32 women and men completed the two-day oat-based intervention, reducing their usual caloric intake by approximately half. A control group of 15 individuals also reduced their calorie intake but did not consume oats. A separate six-week phase involved participants consuming 80 grams of oatmeal daily without additional dietary restrictions, but this approach yielded only modest changes.
The study employed a randomized controlled trial (RCT) design, considered the gold standard in medical research. Participants were randomly assigned to either the oat-based intervention or the control group. While complete blinding (where participants are unaware of their group assignment) was challenging due to the nature of the diet, laboratory teams analyzing blood and stool samples were blinded to group allocation, minimizing potential bias. Researchers collected blood and stool samples, measured blood pressure, weight, and body composition before, during, and after the interventions.
Blood samples were analyzed for LDL cholesterol levels and dihydroferulic acid, while stool samples were used to identify bacterial species and their metabolic byproducts.
Implications and Future Research
The cholesterol-lowering effects observed in the study persisted for six weeks after the two-day intervention, suggesting a potential for sustained benefits. “A short-term oat-based diet at regular intervals could be a well-tolerated way to keep the cholesterol level within the normal range and prevent diabetes,” suggests Professor Simon.
However, the most significant benefits were observed when oats were consumed in larger quantities alongside calorie restriction. Future research will focus on determining whether repeating this intensive oat-based diet every six weeks can provide long-term preventative effects. The study received funding from several organizations, including the German Federal Ministry of Education and Research, the German Diabetes Association, and the German Cereal Processing, Milling and Starch Industries’ Association.
This research offers a potentially accessible and relatively simple dietary strategy for individuals at risk of or managing metabolic syndrome. While not a replacement for conventional medical treatments, incorporating short periods of intensive oatmeal consumption may offer an additional tool for promoting heart health.
