NEW YORK, Jan 25: A short-term oat-based diet may effectively reduce cholesterol levels, according to a trial conducted by the University of Bonn and published in Nature Communications.

The study focused on participants with metabolic syndrome, a combination of high body weight, high blood pressure, and elevated blood glucose and lipid levels. Volunteers consumed a calorie-reduced diet consisting almost exclusively of oatmeal for two days. Researchers found a significant improvement in cholesterol levels compared to a control group, with the effect remaining stable even six weeks later.

The diet also appeared to alter the composition of gut microorganisms, which may contribute to its beneficial effects.

“Today, effective medications are available to treat patients with diabetes,” said Marie-Christine Simon, junior professor at the Institute of Nutritional and Food Science at the University of Bonn. “As a result, this method has been almost completely overlooked in recent decades.”

Although participants were not diabetic, they suffered from metabolic syndrome, which increases the risk of diabetes. The 32 volunteers ate 300 grams of oatmeal per meal for two days, consuming roughly half their usual calorie intake, with only fruit or vegetables allowed as additions. A control group followed a calorie-reduced diet without oats.

Both groups benefited from calorie reduction, but the oat-based group saw more pronounced effects. “The level of particularly harmful LDL cholesterol fell by 10 percent,” Simon said. Participants also lost an average of two kilograms and experienced slight reductions in blood pressure.

High LDL cholesterol is associated with plaque formation in blood vessels, which can lead to heart attacks or strokes.

The researchers suggest the diet’s effects may be linked to gut bacteria. “Oat consumption increased the number of certain bacteria in the gut,” said Linda Klümpen, lead author of the trial. These microbes break down oats to produce compounds such as ferulic acid, which have been shown in animal studies to support cholesterol metabolism. Other bacteria help eliminate histidine, an amino acid linked to insulin resistance, a key factor in diabetes.

Simon said the positive effects were still evident six weeks after the short-term diet. “A short-term oat-based diet at regular intervals could be a well-tolerated way to maintain normal cholesterol levels and prevent diabetes,” she noted.

The study also included a six-week trial with participants consuming 80 grams of oats daily without calorie restriction, which showed smaller effects. Researchers plan further studies to determine whether periodic intensive oat-based diets could have a lasting preventative impact.

A total of 68 participants took part in the trial, with 32 completing the two-day intensive diet and 34 completing the six-week study. Both studies were randomized controlled trials, with blood and stool samples collected and analyzed to assess cholesterol levels, gut microbiome composition, and metabolic by-products.

“The results highlight the potential of simple dietary interventions to improve metabolic health,” Klümpen said.