2024-09-08 06:30:38
Whether kimchi, kefir or pickled onions – fermented foods have reached the top gastronomy. But more and more people are not only eating them because they easily tingle and offer unique taste experiences – they hope to do something good for their health. After all, they say it helps the intestines, strengthens the immune system, prevents cancer and even makes you happy. Is this old? What do researchers know about the supposed healing power of fermented foods?
Vitamins, minerals, proteins
“In principle, fermentation corresponds to pre-digestion,” says Silke Restemeyer, nutritionist at the German Nutrition Society. While the food is cooking, the “good” bacteria, such as lactobacilli, multiply, break down the plant cell and break down the proteins. “This makes the finished fermentation product easier to digest than the raw starting product,” says Resemeyer. “This fermentation process can also improve the absorption of proteins, vitamins and minerals such as zinc.”
It is well known as sauerkraut that saved the crew. In the 18th century, British captain James Cook is said to have discovered that he could save his crew from scurvy with sauerkraut. The disease is due to vitamin C deficiency. Cabbage vitamins can be stored in sauerkraut for months. Studies have confirmed that fake foods sometimes contain more vitamins than the original product, such as B vitamins and vitamin K.
The effect is difficult to prove
To what extent can the body use food produced by bacteria? The state of research is less clear than some kimchi fans have suspected. The findings are often based on laboratory studies, explains Resemeyer, in which individual elements are examined. The health of test subjects is not necessarily tested; Restemeyer says: “That doesn’t mean there’s no health-promoting effect, it’s just hard to prove.” Unlike drugs, there is no big company behind sauerkraut that wants to prove the healing effects of its product.
One thing is clear: fermented foods, even if they are not pasteurized, have many healthy bacteria – and also provide them with food. This helps the microbiome in the gut, as an important study from 2021 shows: In it, scientists from Stanford University served fermented vegetables, kefir, milk or kombucha to 18 Americans every day for ten weeks . Analysis of stool samples showed: the microbiome of the test subjects became more diverse. “We think that the more flora in the gut, the healthier it is,” says Miriam Popkes, who studies molecular medicine and has researched the link between the microbiome and aging in Max Planck Institute for Biology of Aging. She has now founded the company Fermentwelten with her husband. Here they advise those who are interested on the subject of intestinal health and, among other things, teach them how to do it themselves.
Support for intestinal bacteria
A diverse microbiome doesn’t just keep pathogens at bay. How it affects the body is not yet fully understood. But the connections are interesting: people with a different microbiome are less likely to suffer from chronic inflammation, bowel problems, diabetes, high blood pressure and obesity. A study shows: You even have a better chance of surviving cancer. Gut bacteria also seem to affect the psyche: According to studies, those with a different microbiome are less likely to be depressed or anxious. Bacteria like bifidobacteria are linked to happiness.
Previous studies have found substances in fermented foods that have anti-inflammatory effects and strengthen the immune system, for example kefir. Research from Stanford provides evidence that fermented foods also strengthen the immune system: in those who eat fermented foods daily, some immune cells are inactive in blood samples. In addition, the levels of 19 pro-inflammatory interleukins, which increase in inflammation, decrease. One of them, interleukin 6, is linked to rheumatoid arthritis, type 2 diabetes and chronic stress.
The immune system and metabolism
Short chain fatty acids play an important role in the body, including for the immune system. These are produced by intestinal bacteria. Much is not yet understood, but studies show: Short chain fatty acids ensure, among other things, a greater activity of regulatory T cells, which help to regulate the immune system. Anyone who eats fermented foods can support the intestinal bacteria in the production of healthy short fatty acids.
Fermented foods also have an effect on energy production and can even help you lose weight: studies on rats show that short-chain fatty acid acetate (acetic acid) overcomes the blood-brain barrier and acts as a digester in the brain. Acetate and the short-chain fatty acid propionic acid reduce cholesterol production in animal experiments. In laboratory animals, kefir is able to stabilize blood sugar. And in humans, studies have shown that regular yogurt consumption is associated with a lower risk of diabetes.
Yogurt has been shown to promote gut health.Image Alliance / ZoonarTheoretically, fermented milk products can also help with high blood pressure. At least kefir inhibits angiotensin-converting enzyme in laboratory tests. This mechanism of action is also used in drugs against high blood pressure. However, no research has been done on humans to determine whether kefir acts as a blood pressure reducer.
Yoghurt against cancer, Camembert against dementia
Studies on cancer also show that education and practice can make a difference: fermented milk products have substances that are effective against cancer, but in 2022 Chinese researchers analyzed seven studies on people that exist to date. The effect was ambiguous: only yoghurt consumption was associated with a slightly reduced risk of colon cancer.
And how does a healthy diet affect our thinking? Many substances cannot pass from the blood into the brain; But short chain fatty acids can apparently pass through them – and therefore fermented foods can have a positive effect on nerve cells. To date, studies have mainly been on cell models and laboratory animals. Laboratory mice had fewer deposits of beta-amyloid, which is typical of Alzheimer’s, when they regularly ate Camembert. The fatty acid myristamide it contains appears to have a positive effect on the brain. Substances that protect nerve cells are also increased in the brains of laboratory animals. In other studies, memory improved in experimental animals and nerve cells were exposed to harmless oxidative stress.
Neuroscientist John F. Cryan at University College Cork in Ireland investigated whether fermented foods increase our satiety. 24 adults eat “psychobiotic” foods every day, with lots of ferments and fiber. Compared to the control group, they were less anxious. Changes in their microbiome correspond to this. For Cryan, fermented foods are less medicine and more part of a preventative lifestyle. In the future, the following may occur: “When the exam period approaches and you are stressed, you eat more sauerkraut,” he said.
Drink slowly
Most people first want to improve their mental health through fermented foods. In the courses at Fermentwelten you make things together, for example white and cauliflower. Most people are afraid of doing something wrong, Popkes reports. “In the beginning, people often ate solid foods all at once,” says Popkes. The intestinal flora is weakened, resulting in constipation and diarrhea. “You should progress slowly and eat a few forkfuls at first.”
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