Key pointsr Recent studies have indicated that antioxidant supplementation may blunt adaptations to exercise, such as mitochondrial biogenesis induced by endurance training. However, studies in humans are sparse and results are conflicting.r Isolated vitamin C and E supplements are widely used, and unravelling the interference of these vitamins in cellular and physiological adaptations to exercise is of interest to those who exercise for health purposes and to athletes.r Our results show that vitamin C and E supplements blunted the endurance training-induced increase of mitochondrial proteins (COX4), which is important for improving muscular endurance.r Training-induced increases inV O 2 max and running performance were not detectably affected by the supplementation.r The present study contributes to understanding of how antioxidants may interfere with adaptations to exercise in humans, and the results indicate that high dosages of vitamins C and E should be used with caution.Abstract In this double-blind, randomised, controlled trial, we investigated the effects of vitamin C and E supplementation on endurance training adaptations in humans. Fifty-four young men and women were randomly allocated to receive either 1000 mg of vitamin C and 235 mg of vitamin E or a placebo daily for 11 weeks. During supplementation, the participants completed an endurance training programme consisting of three to four sessions per week (primarily of running), divided into high-intensity interval sessions [4-6 × 4-6 min; >90% of maximal heart rate (HR max )] and steady state continuous sessions (30-60 min; 70-90% of HR max ). Maximal oxygen uptake (V O 2 max ), submaximal running and a 20 m shuttle run test were assessed and blood samples and muscle biopsies were collected, before and after the intervention. Participants in the vitamin C and E group increased theirV O 2 max (mean ± S.D.: 8 ± 5%) and performance in the 20 m shuttle test (10 ± 11%) to the same degree as those in the placebo group (mean ± S.D.: 8 ± 5% and 14 ± 17%, respectively). However, the mitochondrial marker cytochrome c oxidase subunit IV (COX4) and cytosolic peroxisome proliferator-activated receptor-γ coactivator 1 α (PGC-1α) increased in the m. vastus lateralis in the placebo group by 59 ± 97% and 19 ± 51%, respectively, but not in the vitamin C and E group (COX4: −13 ± 54%; PGC-1α: −13 ± 29%; P ࣘ 0.03, between groups). Furthermore, mRNA levels of CDC42 and mitogen-activated protein kinase 1 (MAPK1) in the trained muscle were lower in the vitamin C and E group than in the placebo group (P ࣘ 0.05). Daily vitamin C and E supplementation attenuated increases in markers of mitochondrial biogenesis following endurance training. However, no clear interactions were detected for improvements inV O 2 max and running performance. Consequently, vitamin C and E supplementation hampered cellular adaptations in the exercised muscles, and although this did not translate to the performance tests applied in this study, we advocate caution when considering antioxidant supplemen...

Abstract. The present study investigated the diet and quality of life of irritable bowel syndrome (IBS) patients in comparison to the background population. Furthermore, it studied the effects of guidance on diet management on changes in food intake, quality of life and symptoms. A total of 35 healthy controls, 36 IBS patients and 43 IBS patients who had received guidance on diet management 2 years earlier were included. The controls and patients were asked to complete an FFQ questionnaire, an SF-NDI questionnaire, an IBS-QoL questionnaire and a Birmingham IBS symptom score questionnaire. There were no statistical differences in the intake of calories, carbohydrates, proteins and fat between the controls and IBS patients, with or without guidance on diet management. IBS patients made a conscious choice to avoid certain food items, some of which belong to fermentable oligosaccharides, disaccharides, monosacharides and polyols (FODMAPs). They had a higher consumption, however, of other food items that are rich in FODMAPs. They also avoided other food sources which are crucial for their health. Two years after receiving guidance on diet management, IBS patients had a different diet profile. They avoided all FODMAP-rich food, consumed more food with probiotic supplements and did not avoid food sources that were crucial to their health. In addition, they had improved quality of life and reduced symptoms. Although at first sight the diet of IBS patients did not differ from that of the background population, detailed examination showed avoidance of certain food items. Guidance on the management of diet improved their choice of a healthier diet, improved quality of life and reduced IBS symptoms. IntroductionIrritable bowel syndrome (IBS) is a chronic gastrointestinal disorder in absence of any structural, physiological or biochemical abnormalities in the gastrointestinal tract (1). The condition is classified as a functional disorder for which the diagnosis is based on the presentation of symptoms. These symptoms are abdominal discomfort or pain, bloating and abdominal distension, and changes in bowel habit between diarrhoea and constipation (1). The degree of symptoms varies in different patients from tolerable to severe, where the experience of pain may vary from a nagging, colicky, sharp or dull feeling of pain. Also, the time pattern and discomfort varies immensely from patient to patient (2-14). Some complain of daily symptoms, while others report intermittent pain at intervals of weeks/months. The supportive symptoms mentioned above may also be used to subclassify IBS patients into three subtypes: diarrhoea-predominant (IBS-D), constipationpredominant (IBS-C) and alternating constipation/diarrhea (IBS-M) (2-4).The estimated prevalence of IBS varies from 12 to 30%; this large variation is explained by the use of different definitions in different studies (15). A cross-sectional population-based survey conducted in Oppland and Hedmark County in Norway using recent diagnostic criteria estimated the prevalence to affe...

Abstract. Most patients with irritable bowel syndrome (IBS) believe that diet plays a significant role in inducing IBS symptoms and desire to know what foods to avoid. It has been found that the intake of calories, carbohydrates, proteins and fat by IBS patients does not differ from that of the background population. IBS patients were found to avoid certain food items that are rich in fermentable oligo-, di-and monosacharides and polyols (FODMAPs), but they did have a high consumption of many other FODMAP-rich food items. The diet of IBS patients was found to consist of a low calcium, magnesium, phosphorus, vitamin B2 and vitamin A content. There is no consistent evidence that IBS patients suffer from food allergy, nor is there documented evidence that food intolerance plays a role in IBS symptoms. Abnormalities in gut hormones have been reported in IBS patients. As gut hormones control and regulate gastrointestinal motility and sensation, this may explain the abnormal gastrointestinal motility and visceral hypersensitivity reported in these patients. Guidance concerning food management which includes individually based restrictions of FODMAP-rich food items and individual evaluation of the effects of protein-, fat-and carbohydrate-rich/poor diets may reduce IBS symptoms.

BackgroundThe gut hormones are important in regulating gastrointestinal motility. Disturbances in gastrointestinal motility have been reported in patients with irritable bowel syndrome (IBS). Reduced endocrine cell density, as revealed by chromogranin A, has been reported in the colon of IBS patients.AimsTo investigate a possible abnormality in the colonic endocrine cells of IBS patients.MethodsA total of 41 patients with IBS according to Rome Criteria III and 20 controls were included in the study. Biopsies from the right and left colon were obtained from both patients and controls during colonoscopy. The biopsies were immunostained for serotonin, peptide YY (PYY), pancreatic polypeptide (PP), entroglucagon, and somatostatin cells. Cell densities were quantified by computerized image analysis.ResultsSerotonin and PYY cell densities were reduced in the colon of IBS patients. PP, entroglucagon, and somatostatin-immunoreactive cells were too few to enable reliable quantification.ConclusionThe cause of these observations could be primary genetic defect(s), secondary to altered serotonin and/or PYY signaling systems and/or subclinical inflammation. Serotonin activates the submucosal sensory branch of the enteric nervous system and controls gastrointestinal motility and chloride secretion via interneurons and motor neurons. PYY stimulates absorption of water and electrolytes, and inhibits prostaglandin (PG) E2, and vasoactive intestinal peptide, which stimulates intestinal fluid secretion and is a major regulator of the “ileal brake”. Although the cause and effect relationship of these findings is difficult to elucidate, the abnormalities reported here might contribute to the symptoms associated with IBS.