Stress really makes us sick, reducing our defenses over the years. Today we have the proof, but, fortunately, along with this we also have the remedy. In fact, a healthy diet and moderate physical activity can compensate for the damage of stress on the immune system. These results emerged thanks to the work just published in the prestigious PNAS journal, Proceedings of the National Academy of Sciences, thanks to a team of American scientists from the University of South California (Klopack et al, PNAS, Jun 2022).
Aging, stress and the immune system
We all get old, but something can make us grow old and sick much faster, stress. This is what American scientists have observed. The researchers started from the premise that, with the same age, there are people who get sick more than others. But how can this difference be explained? It is known that, over time, the immune system weakens and there are more and more old and tired white blood cells in circulation and fewer and fewer young white blood cells ready to fight against external threats. Well, for some reason there are more old and tired white blood cells in some people while in other people there are more young and fresh white blood cells. It should be emphasized that a weak and "old" immune system paves the way for cardiovascular disease, cancer, pneumonia, infections such as COVID 19 and systemic organ aging. It is therefore clear that it becomes vitally important to understand what can make the immune system age faster. Stress seems to be an important candidate and precisely to verify the effect of stress on our defenses, the researchers developed the study we are talking about today.
Stress lowers the defenses, a healthy diet raises them
The research was carried out in the context of a large study, the University of Michigan's Health and Retirement Study, aimed at people over 50. 5,744 adults over 50 were recruited for the research. All were asked to fill in a questionnaire in order to assess the degree of stress, such as events perceived as traumatic, any discrimination and chronic stress. Then, the blood of all the volunteers was analyzed in order to assess the status of the white blood cells. What emerged was that those subjected to the greatest stress had a higher percentage of old, underactive white blood cells and fewer new, active white blood cells in their blood. Instead, it was noted that, among those most stressed, eating a healthy diet and having an active lifestyle could, at least in part, compensate for the damage of stress. The explanation is as follows. The thymus is a gland located just above the heart. In the thymus, white blood cells can mature and become an active part of the immune system. With advancing age, with stress, poor nutrition and a sedentary lifestyle, the thymus tissue shrinks and gives way to adipose tissue. Thus, gradually, the production of white blood cells decreases and our immune system ages.
Certainly we cannot avoid aging and we cannot completely eliminate stress from our life, in fact there will always be an event that we consider a threat. It is therefore clear how important it is to ensure a healthy and varied diet and an active lifestyle, such as, for example, taking a brisk walk every day, in order to protect our natural immune defenses and reduce the risk of getting sick.