Study: rural residents who come into contact with farm animals are better able to cope with stressful situations
Despite technological advances, the work pressure among many citizens is increasing. Those who are constantly stressed are also more susceptible to diseases. Rural residents obviously have a clear advantage here. Because, as has now been shown in a study, people who grew up in the countryside and have close contact with farm animals can cope better with stressful situations.
Healthy country life
Increasing work pressure and stress endanger health. Relaxation and rest are important for people. The best way to switch off is to go outdoors or in the country. Because that's where most people can relax best. But what makes country life so healthy and relaxing? The rural calm, the fresh air or the intact neighborhood? Scientists at the University of Ulm have a completely different answer: rural residents who have close contact with farm animals are able to cope with stress situations immunologically much better than city dwellers who grew up without pets. They get help from the "old friends" among the microbes.
Trial participants under increasing pressure
"This refers to environmental bacteria with which humans have lived together peacefully for thousands of years and that have a hard time in the big city today," explains Professor Stefan Reber in a statement from the university.
The head of the Section for Molecular Psychosomatics at the Ulm University Clinic for Psychosomatic Medicine and Psychotherapy, together with colleagues from the Ulm University Clinic and researchers from Erlangen, London and Boulder (Colorado), found that men who lived the first 15 years on a farm with livestock farming grew up able to handle psychosocial stress better than men who spent the first 15 years of their lives in a big city with over 100,000 inhabitants and without pets.
For their study, which was recently published in the journal "PNAS", the researchers subjected a total of 40 healthy male test subjects to a stress test and, in addition, stress hormones and immunological parameters.
The subjects were "stressed" in a standardized laboratory experiment using the so-called "Trier Social Stress Test" (TSST).
The test participants are exposed to a fictitious application situation and are put under increasing pressure. In the meantime, you have to solve mental arithmetic problems and start over again if you make mistakes.
Before and after the test, the scientists took blood and saliva samples in order to collect certain immune cells such as mononuclear cells of peripheral blood (PBMC) or to record stress parameters such as cortisol.
The rural population's immune system was less provoked by the stress
The result was that the “rural residents” in the test showed higher stress levels than the “big cities”; Both the basal stress hormone levels were higher and the subjective feeling of stress asked in the questionnaire.
On the other hand, the immune system of the “rural residents” could not be provoked to react as strongly as that of the “city dwellers” who had no contact with animals in their childhood.
Thus, not only was the stress-induced increase in PBMC greater in the subjects who grew up in the city without animals, but also the values for the inflammation marker interleukin 6 remained higher than in the comparison group.
The scientists also found another clear indication that the immune system of the “rural residents” coped better with stress.
For this purpose, the isolated mononuclear cells of the peripheral blood were examined for the release of the anti-inflammatory agent Interleukin 10.
The result: after the stress test, the release of this anti-inflammatory substance was significantly reduced in the animal-free townspeople, but not in the countries close to livestock.
Chronic inflammatory reactions
Excessive immune responses are a problem for health because they often lead to chronic inflammatory reactions.
"Such processes play a role in the development of asthma and allergic diseases, for example, but they also increase the risk of mental illnesses such as depression and post-traumatic stress disorder," explains Stefan Reber, a psychoneuroimmunologist from Ulm.
It has been known for a long time that the susceptibility to asthma and allergies as well as to mental illnesses in people living in the big city is above average, or that farm life protects against allergies.
With the global trend towards urbanization - more and more people are moving from the countryside to the metropolises - this finding is becoming even more explosive.
Research has suspected that the lack of contact with certain bacteria plays a key role, as the so-called "missing microbes" hypothesis states.
"Vaccination" with environmental bacteria
In a previous experiment with mice, a research team led by Professor Reber was able to show that the stress resilience of animals can be improved by “vaccinating” with such well-known environmental bacteria.
Of course, it would be nice if the results could be transferred from the mouse to humans. In the future, such a vaccination could possibly also work for human risk groups.
In a follow-up study, the scientists want to find out whether early contact with pets may also do so in the city. (ad)