The importance of serotonin in regulation of central (mood, hunger) and peripheral (intestinal) functions has long been established. Nutritive interventions however, e.g. the increase in dietary tryptophan -the metabolic precursor of serotonin -for the treatment of eating disorders (anorexia), mood disorders (depression), migraine, and the irritable bowel syndrome have not produced significant Results: The unbalanced population prevalence of these disorders in men and women allows concluding a contribution of gender to the efficacy such interventions. Shortterm depletion of tryptophan from food (called acute tryptophan depletion, ATD) has been shown to provoke the respective symptoms both in healthy volunteers as well as in patients, but seems to work predominantly in women. Therefore, gender differences must exist in the serotonin metabolism and its utilization in the brain and in the periphery. In addition, genetic predisposition has been shown to exist that determines -among others -the effectiveness of serotoninergic interventions in patients, with drugs as well as with nutrients. We will review the current evidence for the contribution of gender on food, mood, and genetic determinants of serotonin utilization. In the U.S. and other western industrial countries more women than men seek health care services for irritable bowel syndrome (IBS). In addition, the health care impact of IBS also appears to be greater in women as compared to men. Women with IBS commonly report other somatic and visceral symptoms. Muscle and joint pain and disturbed sleep patterns are among the most common and the most distressing. Gender differences exist in types of GI symptoms (women report greater problems with constipation while men more frequently report diarrhea) as well as other extra-intestinal symptoms. The role of menstrual cycle in IBS symptom reporting is based on observations that women with IBS frequently report cyclic changes in their symptom severity. Women with IBS often report other menstrual cycle linked conditions including migraine headache, dysmenorrhea and premenstrual dysphoria distress syndrome. Gender differences in IBS begin to emerge at puberty. In children, the rubric of recurrent abdominal pain (RAP) includes IBS, functional abdominal pain, and likely, dyspepsia. Prior to puberty there is an equal proportion of boys and girls with a diagnosis of RAP. The factors responsible for the divergence in prevalence after puberty are not clear. Studies suggest that both environmental (i.e., increased risk if a parent has IBS) and gender factors (i.e., changes in hormonal milieu) likely play a role. The incidence of IBS in both men and women appears to decrease in late middle age. The severity of GI symptoms, including abdominal pain, altered bowel habits, and bloating, varies across phases of the menstrual cycle as well as during the menopause transition in some women with or without IBS or other functional GI disorders. A limited number of studies indicate that premenses (days immediately preceding the onset of menses) and menses, compared with other cycle phases, are periods of increased GI symptom distress in women age 19-37. Women with IBS experience a greater impact of menstrual cycle on symptoms as compared to those without IBS. While not extensively studied, oral contraceptives appear to modestly reduce but not eliminate GI symptoms in those with IBS. This paper will present they hypothesis that declining or low ovarian hormone levels underlies the occurrence or exacerbations of abdominal pain/discomfort across the menstrual cycle and the perimenopause-early menopause transition in women with or without IBS. Increased availalability of data and recent developments in longitudinal modelling improve the possibilities to understand the long-term development of health. The symposium will present four papers exploring trajectories of health and health-related behavior -based on annual measurements over 9-18 years -in relation to retirement, sickness absence, and socioeconomic status. The two first papers show that retirement was associated with a substantial decrease in fatigue, depressive symptoms, and increase in adherence to medical treatment among individuals with chronic hypertension following retirement. Poor adherence before retirement was more common among individuals exposed to high work stress. The third paper shows that the association between diagnosis-specific sickness absences and sustained sub-optimal health varies by socioeconomic position. While the association with self-rated health was significantly stronger for mental disorders than for musculoskeletal disorders in the higher grades, the inverse was true in the lower grades. The fourth paper shows that weight continues to increase in the transition between midlife and old age, and that this increase is greater in the lower socioeconomic groups. As discussant, research director Archana Singh-Manoux will highlight the methodological possibilities and challenges in understanding the long-term development of health. Objectives: To determine, using longitudinal analyses, if retirement is followed by a change in the risk of incident chronic diseases, depressive symptoms, and fatigue. Design, Setting, and Participants: A prospective cohort study with multiple repeated annual surveys from seven years before through seven years after retirement in a large French occupational cohortthe GAZEL study -of 11,246 men and 2,858 women. Data were collected by questionnaire each year from 1989 through 2007 inclusive. Main Outcome Measures: Respiratory disease, diabetes, cardiovascular disease and stroke, mental fatigue, and physical fatigue, measured each year of the 15-year observation period, and depressive symptoms, measured at four time points. Results: Repeated-measures logistic regression with generalized estimating equations showed that the cumulative prevalence of respiratory diseases, diabetes, and cardiovascular disease and stroke increased with age, with no break in the trend around retirement. In contrast, we found retirement to be associated with a substantial decrease in the prevalence of both mental fatigue (odds ratio [OR] for fatigue one year after versus one year before the retirement 0.19; 95% CI 0.18 to 0.21) and physical fatigue (OR 0.27; CI 0.26 to 0.30). A slightly smaller decrease was observed in depressive symptoms (OR 0.60; CI 0.53 to 0.67). The decrease in fatigue around retirement was more pronounced among those with chronic disease before retirement.