• Posted March 4, 2026

Two Days of Oatmeal May Lower Cholesterol, Study Finds

Whether topped with fruit or flavored with peanut butter, eating mostly oatmeal for just two days may help lower cholesterol, according to a new study out of Germany.

In the trial, people with metabolic syndrome who followed a strict oat-based plan for 48 hours saw a 10% drop in harmful LDL cholesterol.

The improvement was still noticeable six weeks later, researchers at the University of Bonn recently reported in the journal Nature Communications.

Metabolic syndrome is a collection of health problems that includes excess weight, high blood pressure, high blood sugar and unhealthy cholesterol levels. These conditions raise a person’s risk for heart disease and type 2 diabetes.

During the two-day phase of the study, volunteers ate 300 grams of oatmeal per day, split into three meals. They were only allowed to add small amounts of fruit or vegetables. At the same time, they cut their normal calorie intake by about half.

A control group also reduced calories but did not eat oats.

In all, 32 women and men completed the two-day oat plan: 17 in the oat group and 15 in the control group.

Two people in the control group had to drop out for personal reasons. Overall, 68 folks took part in the research, which also included a longer, six-week phase.

Both groups benefited somewhat from eating fewer calories. But the oat group saw stronger changes.

"The level of particularly harmful LDL cholesterol fell by 10% for them — that is a substantial reduction, although not entirely comparable to the effect of modern medications," study co-author Marie-Christine Simon, a junior professor at the university’s Institute of Nutritional and Food Science, said in a news release.

"As a result, this method has been almost completely overlooked in recent decades," she added.

Participants in the oat group also lost about 4.4 pounds on average, and their blood pressure dropped slightly.

Lowering LDL cholesterol is important because high levels can cause buildup in artery walls. Over time, this can lead to heart attack or stroke.

Researchers also looked at what was happening inside the gut.

"We were able to identify that the consumption of oatmeal increased the number of certain bacteria in the gut," said lead author Linda Klümpen, a doctoral candidate at the institute.

Gut bacteria help break down food and create substances that affect health. The team found that oats helped bacteria produce compounds called phenolic substances.

One of them, ferulic acid, has been shown in animal studies to support healthy cholesterol levels.

“We were able to show that intestinal bacteria produce phenolic compounds by breaking down the oats,” Klümpen said in a news release.

The researchers also noted that some gut microbes help remove histidine, an amino acid that can be converted into a compound linked to insulin resistance if it builds up.

In a separate part of the study, participants ate 80 grams of oatmeal per day for six weeks without dietary limits. That approach led to only modest changes, researchers noted.

The biggest improvements came from the two-day plan.

"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," Simon said.

The research randomly assigned participants were to oat or control groups.

While people knew what they were eating, lab teams that analyzed blood and stool samples did not know which group the samples came from.

Researchers measured blood pressure, weight, waist size and body fat before and after the intervention, and again at two, four and six weeks.

The study was funded by several German research organizations and food industry groups.

More information

PubMed Central has more on the health benefits of oats.

SOURCE: University of Bonn, news release, Feb. 25, 2026