Each year, over 30 million Americans suffer from acute or chronic digestive dysfunction. Much of this dysfunction is associated with occupational and behavioral stresses, which, although not life threatening, cause absenteeism and claim considerable health services. Central nervous system gastrointestinal (GI) peptide hormones partly control the quantity and quality of food eaten and its digestion. Because digestion is modified by occupational stress and behavior patterns, including smoking and consumption of alcohol and coffee, the physiological status of the individual plays a major role in the absorption of luminal nutrients. Whereas a Western, versus vegetarian, diet has been associated with an increase in coronary heart disease and diet-related cancers, inadequate attention has been given to the effects of life-style and occupation. This review is concerned with the adverse environmental effects on digestion that act via changes in GI function. To reduce the incidence of digestive dysfunction and diet-related diseases, more attention must be given to environmental factors other than diet, which affects the absorption of nutrients.