The following is a summary of the talk given by Dr. Nicholas Hall on October 21, 2001, at the major session planned in conjunction with VN DPG titled “The Food- Mood Connection Veggie Style” at the Food & Nutrition Conference Exhibition held in St. Louis, Missouri.
Today, stress is a common topic of interest and is recognized as a way of life. The term “stress” refers to the state of an organism that has been subjected to a stimulus perceived as a threat. This threat is termed a stressor. Selye also described stress as a state manifested by a specific syndrome that consists of all the non-specifically induced changes within a biological system [1]. The condition refers to a wide range of physiological responses of the body that are induced by various environmental, psychological and physical factors or stressors independently or in combination for either a short or long period of time.
The physiological stress responses involve the activity of the nervous and endocrine systems and are manifested as disruptions in the homeostasis of various body systems and organ responses. The exposure to the stressor(s) causes an activation of the autonomic nervous system resulting in an endocrine response such as an increase or decrease in the secretion of various hormones in the body. In this regard, stress can be viewed as an accumulation of a large number of negative consequences termed as distress or relatively few negative consequences or eustress. Stress responses are individualistic in that there is a high degree of variability between individuals and within the same individual. For example, a stressor to one individual need not be stressful to another and a stressor to an individual at a particular time may no longer be a stressor at a later point in life [1].
Physical/environmental stressors include environmental pollutants, temperature changes, immobilization, decreased oxygen supply, prolonged exercise, hypoglycemia, injuries, infections and trauma to the body. Psychological stressors include personal thoughts, feelings about real or imagined threats and social interactions.
Stress responses can be detected by measuring physiological responses such as heart rate, breathing rate, blood pressure, skeletal muscle tension, skin potential and electrodermal response as well as circulating and urinary levels of stress hormones namely catecholamines, epinephrine and norepinephrine, and the corticosteroids, cortisol and its metabolites [1].
The stress response is basically a currency transaction. Energy is shuttled from storage inside cells to where it is needed within the body, a process that requires insulin and cortisol. It is a costly process with considerable energy being used to engage this biochemical machinery. This has been hypothesized to lead to a craving for carbohydrate. Carbohydrate is broken down into sugar comparatively rapidly and therefore is a good source of quick energy. While the right foods can contribute to optimal performance and health, the wrong choices will set the biological stage for fatigue, irritability and a derailed immune system which are often associated with chronic stress and depression. There is more to the health equation than diet. Exercise, adequate sleep and attitude are all important for optimal health.
Depression exists in many forms. It can be a reactive sadness lasting just a few hours or days or long-term grief experienced following a major interpersonal loss. Medical illness and medications can also trigger depression. Thyroid disorders, rheumatoid arthritis and chronic pain can trigger symptoms of depression as can antianxiety drugs, birth control pills and alcohol. Clinical depression is associated with a chemical imbalance in the brain with no known association with environmental events such as loss or medications. For example, a drop in brain levels of norepinephrine or serotonin have each been associated with some forms of negative effects - the types typically treated with monoamine oxidase inhibitors or perhaps selective serotonin re-uptake inhibitors. The best-documented link between the foods we eat and depression involves the synthesis of serotonin and the consumption of carbohydrates.
Carbohydrates, especially those with a high glycemic index, are more rapidly converted into sugar than other food types. The subsequent rise in insulin triggered by the conversion of carbohydrates into sugar facilitates the transport of serotonin's precursor (tryptophan) into the brain. Provided all the enzymatic machinery is working properly, brain tryptophan can be converted into serotonin. What does this have to do with depression? Research at MIT has shown that the same drop in serotonin that can give rise to some forms of depression can trigger a craving for carbohydrates. It is as though the brain is self-medicating itself by controlling dietary preferences. However, there is a note of caution. A shortage of vitamin B6 as well as other problems may impair serotonin production. Then, pigging out on lasagna will simply change the contour of your body, not the contour of your mind. Other neurotransmitters are involved as well, including norepinephrine, which is modulated by estrogen.
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