The fact that oats have a beneficial effect on the metabolism is nothing new. German medic Carl von Noorden treated patients with diabetes with the cereal at the beginning of the 20th century – with remarkable success. “Today, effective medications are available to treat patients with diabetes,” explains 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 the test subjects in the current trial were not diabetic, they suffered from a metabolic syndrome associated with an increased risk of diabetes. The characteristics include excess body weight, high blood pressure, an elevated blood sugar level, and lipid metabolism disorders. “We wanted to know how a special oat-based diet affects patients,” explains Simon, who is also a member of the Transdisciplinary Research Areas “Life & Health” and „Sustainable Futures“ at the University of Bonn.
300 grams of oatmeal per day
The participants were asked to exclusively eat oatmeal, which they had previously boiled in water, three times a day. They were only allowed to add some fruit or vegetables to their meals. A total of 32 women and men completed this oat-based diet. They ate 300 grams of oatmeal on each of the two days and only consumed around half of their normal calories. A control group was also put on a calorie-reduced diet, although this did not consist of oats.
Both groups benefited from the change in diet. However, the effect was much more pronounced for the participants who followed the oat-based diet. “The level of particularly harmful LDL cholesterol fell by 10 percent for them – that is a substantial reduction, although not entirely comparable to the effect of modern medications,” stresses Simon. “They also lost two kilos in weight on average and their blood pressure fell slightly.”
The effect on LDL cholesterol, in particular, is likely to be relevant to health. If the blood contains too much of this, it is deposited in the vessel walls. These deposits, known as plaques, narrow the blood vessels. In addition, the deposits can rupture, for instance due to an increase in blood pressure following physical exertion, anger, or stress. As a result, a blood clot can form at the affected site, completely blocking the blood vessel. Alternatively, parts of the plaque can be washed away by the blood and cause a heart attack or stroke.
Oats promote the growth of “healthy” intestinal bacteria
But how does oatmeal exert its beneficial effect? “We were able to identify that the consumption of oatmeal increased the number of certain bacteria in the gut,” explains Simon’s colleague Linda Klümpen, the lead author of the trial. The microbiome has increasingly been the focus of research in recent decades. After all, it is now known that intestinal bacteria play a decisive role in metabolizing food. They also release the metabolic by-products that they create into their environment. They supply, among other things, the cells of the gut with energy, enabling them to better perform their tasks.
In addition, the microbes send some of their products around the body in the blood stream, where they can have various effects. “For instance, we were able to show that intestinal bacteria produce phenolic compounds by breaking down the oats,” says Klümpen. “It has already been shown in animal studies that one of them, ferulic acid, has a positive effect on the cholesterol metabolism. This also appears to be the case for some of the other bacterial metabolic products.” At the same time, other microorganisms “dispose of” the amino acid histidine. The body otherwise turns this into a molecule that is suspected of promoting insulin resistance. This insensitivity to insulin is a key feature of diabetes mellitus.
A large amount of oats for two days better than a small amount for six weeks
... continue reading