It is no secret that stress is linked to disease. Some have even argued that nearly every disease has stress as a contributing factor. Most people think of stress only as psychological stress—worry, anxiety, or emotional strain—but stress takes many forms.
There is structural stress, such as muscle spasm or spinal imbalance. There is chemical stress from poor diet or toxic exposures. There is immune stress from microorganisms that challenge the immune system. There is also thermal stress from exposure to extreme heat or cold. Each of these stresses places a physiologic burden on the body.
Research published in Epidemiology (May 2001;11:345–349) found that psychological stress increases the likelihood of developing a common cold. Individuals with a persistently negative outlook were found to be at even greater risk.
One reason stress contributes to illness is that it tends to push people toward unhealthy behaviors. Research published in Preventive Medicine (January 2002;34:29–39) found that many people overeat in response to stress. Researchers at the University of California, San Francisco identified a feedback mechanism in rats that may help explain cravings for so-called “comfort foods.” In response to stress, rats produce corticosterone—the rodent equivalent of the human stress hormone cortisol. About 24 hours later, this hormone drives pleasure-seeking behavior, increasing cravings for calorie-dense foods such as sugar and fat. In people, this same mechanism may promote cravings for chocolate, fried foods, or other high-calorie options.
Stress also has a direct suppressive effect on the immune system. A major review published in Psychological Bulletin (July 2004) analyzed nearly 300 studies spanning more than 40 years. Chronic stress was found to be particularly harmful. The longer a stressor persists, the more it interferes with the body’s ability to adapt, and the more likely it is to result in long-term health consequences. Chronic stress disrupts immune function at the cellular level and weakens the immune system as a whole.
Research published in Psychosomatic Medicine (March 1999;61:175–180) found that stress can intensify the symptoms of common viral illnesses such as colds and influenza.
Stress has also been linked to metabolic disease. A study published in Diabetes Care (February 2000;23:197–201) examined approximately 2,000 adults and assessed major life stressors such as bereavement, relationship loss, and long-term financial strain. Individuals reporting the highest number of serious stressors were 60% more likely to have type 2 diabetes than those reporting fewer stress events.
The effects of stress can emerge many years later. Research published in the American Journal of Public Health (October 2001;91:1671–1678) found that psychological distress at age 23 increased the likelihood of low back pain at age 33 by two and a half times.
Stress has been associated with high blood pressure, cardiovascular disease, accelerated aging of the skin, and even birth defects. Research appearing in The Lancet (September 9, 2000;356:875–880) found that stress during pregnancy was associated with an 80% increase in birth defects. Severe stress—such as the unexpected death of a child—was associated with an eight-fold increase.
Stress is cumulative. Dietary stress adds to emotional stress. Chemical exposures add to structural strain. When manageable stressors are addressed, the body is better able to cope with stressors that cannot be avoided. Supporting the body through nutrition, lifestyle strategies, and structural balance may help reduce the physiologic burden imposed by chronic stress.
