Those who need to change their eating habits to normalize their blood pressure should start fasting. Scientists explain why patients can use it as a tool to improve their long-term health. Many people suffer from the metabolic syndrome. Several of the four diseases of affluence occur simultaneously in this 'deadly quartet':obesity, hypertension, lipid metabolism disorder and diabetes mellitus. Each of these factors is a risk factor for serious cardiovascular disease, such as heart attack and stroke. The treatment aims to help patients lose weight and normalize their fat and carbohydrate metabolism and blood pressure. In addition to exercise, doctors prescribe a low-calorie and healthy diet. Medication is often required as well. However, it is not entirely clear what effects food has on the microbiome, the immune system and health.
A research group led by Dr. Sofia Forslund and Professor Dominik N. Müller of the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) and the Experimental and Clinical Research Center (ECRC) has now examined the effect of people with metabolic syndrome . The ECRC is jointly administered by the MDC and Charité Universitätsmedizin Berlin. “Switching to a healthy diet has a positive effect on blood pressure,” Andras Maifeld summarizes the results. “If the diet is preceded by fasting, this effect is enhanced.” Maifeld is the first author of the article.
Broccoli over roast beef
Dr Andreas Michalsen and Professor Gustav J. Dobos recruited 71 volunteers with metabolic syndrome and elevated systolic blood pressure. The researchers randomly divided them into two groups. Both groups followed the DASH (Dietary Approach to Stop Hypertension) diet for three months, which is intended to combat high blood pressure. This Mediterranean diet includes plenty of fruits and vegetables, whole grains, nuts and legumes, fish, and lean white meats. One of the two groups did not eat any solid food at all for five days before starting the DASH diet.
Based on immunophenotyping, the scientists observed how the volunteers' immune cells changed when they changed their diet. “The innate immune system remains stable during fasting, while the adaptive immune system is turned off,” Maifeld explains. During this process, the number of pro-inflammatory T cells decreases, while regulatory T cells multiply.
A Mediterranean diet is good, but fasting is also better
The researchers used stool samples to examine the effects of fasting on the gut microbiome. Gut bacteria work in close contact with the immune system. Some strains of bacteria metabolize dietary fiber into short-chain anti-inflammatory fatty acids that benefit the immune system. The ecosystem composition of gut bacteria changes drastically during fasting. Multiply health-promoting bacteria that help lower blood pressure. Some of these changes persist even after food intake resumes. The following is particularly striking:“Body mass index, blood pressure and the need for antihypertensive drugs remained lower in the long term in volunteers who started a healthy diet with a five-day fast,” explains Dominik Müller. Blood pressure normally rises again when even one antihypertensive drug is forgotten.
Blood pressure stays lower in the long run – even three months after fasting
Together with scientists from the Helmholtz Center for Infection Research and McGill University, Montreal, Canada, Forslund's working group performed a statistical evaluation of these results using artificial intelligence to ensure that this positive effect was actually due to the speed and not the medication the volunteers took. They used methods from a previous study in which they examined the influence of antihypertensive drugs on the microbiome. “We were able to isolate the influence of the medication and see that whether a person responds well to a change in diet or not depends on the individual immune response and the gut microbiome,” says Forslund.
If a high-fiber, low-fat diet does not produce results, there may be insufficient gut bacteria in the gut microbiome that metabolize fiber into protective fatty acids. “Those who have this problem often feel like it's not worth it and go back to their old habits,” explains the scientist. It is therefore a good idea to combine a diet with fasting. “Fasting acts as a catalyst for protective microorganisms in the gut. Health is clearly improving very quickly and patients can reduce their medication or often stop taking tablets altogether.” This could motivate them to stick to a healthy lifestyle in the long term.
