Positive Stress Effect on the Immune System
While stress is known to weaken the immune system under some circumstances, certain types of stress might actually make the immune system stronger, according to a new study in Psychophysiology.1 One of the immune system’s first lines of defense involves secretory immunoglobulin A (S-IgA), a substance found within the lining of the lungs, nose, stomach, and intestines. According to the study, acute stress can either positively or negatively impact S-IgA levels, depending on whether the stress involves mental exertion or passive observation.
To determine the effects of stress on S-IgA, 32 male students between the ages of 18 and 31 participated in three tasks, including watching a video about birds (passive observation), watching a graphic video on surgical procedures (passive stress), or taking a timed memory test (active stress). Other markers of stress were also evaluated, such as blood pressure, heart rate, and an anxiety questionnaire. Students provided saliva specimens before, during, and after the task, from which S-IgA levels were measured.
During the timed exam, there was almost a twofold increase in S-IgA levels, compared with when students watched the bird video. Blood pressure, heart rate, and self-reported anxiety also went up, demonstrating involvement of the "fight or flight" mechanism of the nervous system. Conversely, when students watched the surgical video, S-IgA levels decreased significantly and continued to decrease even ten minutes after the video had stopped. Although students reported an increase in anxiety levels while viewing the surgical video, their heart rates actually decreased, while their blood pressure went up only slightly, leading the scientists to conclude that the "flight or fight" mechanism did not account for the drop in S-IgA.
Decreased levels of S-IgA have been associated with an increased incidence of respiratory tract infections and may contribute to the development of chronic infections in the gut. While stress is generally believed to impair the functioning of the immune system, this study demonstrates that certain types of stress may actually enhance immune function. This may explain why many people stay healthy during stressful times and then get colds and flus once the stress is removed. While it is not clear which mechanisms in the body regulate immune function, it appears that no one component controls the response of S-IgA. However, more research is needed to clarify this point.
1. Bosch JA, de Geus EJ, Kelder A, et al. Differential effects of active versus passive coping on secretory immunity. Psychophysiology 2001;38:836–46.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of Garlic and Cholesterol: Everything You Need to Know (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice in Westport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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