Diet and Gastrointestinal Sensitivities

Statovci et al. (2017) reviews the influences of the westernized diet and its associated nutrients on immune cell responses and the microbiota, explaining how these effects can also affect the pathology of inflammatory bowel disease (IBD) and asthma. The gut microbial community is vital for the development and maturation of both systemic and mucosal immune responses but can be easily disrupted by the hosts’ dietary content. There is a complex relationship between the microbiota, the nutrients, and the immune system that is responsible for maintaining homeostasis and fighting against invading pathogens at mucosal sites. Inflammatory bowel diseases (IBD) and asthma are highly prevalent, chronic mucosal inflammatory conditions with a multifactorial etiology including genetic factors, environmental factors, and uncontrolled immune responses. While genetics play a part in the etiology, diet has been suggested as a major contributor. There is evidence indicating that the intake of a diet high in saturated fat and low in fiber can alter the gut microbiota, triggering the factors that regulate the development of both asthma and IBD. Moreover, studies have increasingly linked the gut with the airways in disease development. [NPIDs: gastrointestinal disorders, Western-style diet, gut-brain axis, IBD, asthma, systemic immune response, mucosal immune response, microbiota, IBD, saturated fat, fiber, microbiome, gut microbiota]

This 2020 review summarizes the recent findings on the impacts of carbohydrates and lipids on the pathophysiology of leaky gut syndrome (a digestive condition in which gaps in the intestinal walls develop and allow bacteria and other toxins to pass into the bloodstream). Binienda et al. explain that when permeability of the intestinal barrier is altered, serious gastrointestinal (GI) disorders may follow. Dietary habits are suggested to affect prevalence rates of intestinal diseases in industrial and developing countries. Diseases associated with highly permeable intestines are also common in Western countries where the diet is traditionally rich in fats and refined carbohydrates. Several studies have implied that fructose is one of the key carbohydrates involved in the regulation of the intestinal permeability, and that its overconsumption may induce harmful effects. To reduce intestinal permeability, short chain fatty acids (mainly butyrate) may be effective in leaky gut syndrome if given at appropriate concentrations. It should be noted that the properties of long-chain fatty acids such as n-3 and n-6 polyunsaturated fatty acids are still unclear. [NPIDs: gastrointestinal disorders, carbs, leaky gut syndrome, intestinal permeability, Western-style diet, WS diet, fructose, butyrate, fatty acids, short-chain fatty acids, long-chain fatty acids, n-3, n-6, polyunsaturated fatty acids]

Barberis et al. (2019) explain that celiac disease (autoimmune disease characterised by malabsorption of nutrients that causes part of the intestine to waste away) has been linked with depression and anxiety symptoms and poor quality of life in several studies but had not been previously considered the role of motivation. This study aimed to examine the relationship between motivation, diet adherence, anxiety symptoms, depression symptoms and physical functioning in people with celiac disease. A sample of 433 adults (18-79 years old) with celiac disease were administered with questionnaires, and the variables were later analyzed. Motivation was discovered to be directly related to diet adherence, anxiety symptoms, depression symptoms and physical functioning. Diet adherence was also revealed to mediate the relationship between motivation and anxiety symptoms, depression symptoms and physical functioning. Since motivation correlated with diet adherence, motivation was shown to be an influential factor in people with celiac disease. Treatments should therefore consider the motivational levels of each celiac disease sufferer too. [NPIDs: gastrointestinal disorders, malabsorption, depression, anxiety, quality of life, diet adherence, celiac, coeliac]

Kortlever et al. (2019) remarks that although the low FODMAP (fermentable oligosaccharide, disaccharide, monosaccharide, and polyol) diet is effective at managing symptoms of irritable bowel syndrome (IBS), the long-term studies have rarely reported quality of life (QoL). This observational study aimed to determine the effect of low-FODMAP diet on long-term QoL, gastrointestinal (GI) and non-GI symptoms in IBS patients. QoL (primary outcome) and the secondary outcomes including GI symptoms, anxiety/depression, fatigue, sleep quality, and happiness were obtained at baseline, 6 weeks (T6), and 6 months (T26). Of the 111 IBS patients recruited, 91% completed baseline, 71.6% reached T6 and 50.5% got to the 6-month mark. When comparing results at T6 and T26 with the baseline measurements, significant improvements were seen in QoL (both p < 0.001) as well as significant reductions in GI symptoms, fatigue and anxiety. Moreover, incidence of depression significantly dropped and both happiness and vitality improved from baseline to T26. There was also a significant correlation between GI symptom response and change in QoL, anxiety, depression, and fatigue (all P < 0.034). These findings support a wider range of benefits for IBS patients consuming a low FODMAP diet. [NPIDs: gastrointestinal disorders, FODMAP, fermentable oligosaccharide, disaccharide, monosaccharide, polyol, IBS, anxiety, depression, fatigue, sleep, sleep quality, happiness]

Since patients with coeliac disease commonly suffer from what is called “brain fog”, Kiristensen et al. (2019) set out to assess symptoms of impaired concentration in patients with coeliac disease before and after treatment with gluten-free diet and compared the data to that of healthy (healthcare personnel) and patient controls [those with inflammatory bowel disease(IBD)]. The study involved participants completing the Adult ADHD Self-Report Scale v1.1 Symptoms Checklist (ASRS)(a questionnaire typically used to assess ADHD which is a disorder sometimes displaying cognitive difficulties), Hospital Anxiety and Depression Scale (HADS) and Gastrointestinal Symptom Rating Scale (GSRS) prior to start of a gluten-free diet and after at least 12 months on the diet. Sixty healthcare personnel served as healthy controls, 36 patients with IBD formed the patient group, while 31 newly diagnosed coeliac patients were included in this study, although 26 of them met for follow-up and repeated the questionnaires. Prior to the gluten-free intervention, coeliac patients reported significantly higher ASRS and HADS scores, relative to the healthy control group but did not significantly differ from patient controls with IBS on any measure prior to the diet. After the transition into a gluten-free diet, the scores of the coeliac patients improved and were found to be not significantly different from the healthy controls. Kristensen et al (2019) discovered that differences in clinical manifestations between those with newly diagnosed coeliac disease and those healthy individuals disappeared after adopting a gluten-free diet for a minimum of 12 months. [NPIDs: gastrointestinal disorders, celiac, coeliac, brain fog, IBD, IBS, anxiety, depression, cognition, gluten]

Casella et al. (2017) gathers evidence in terms of research studies connecting mood disorders with non-celiac gluten sensitivity, a syndrome diagnosed in patients responsive to non-gluten diet where celiac disease and wheat allergy have been ruled out. Dicke first documented in the 1950s the improvement in mood seen when celiac patients were given a gluten-free diet. Goldberg et al. (1970) reported that 34% of the 80 celiac patients that took part in their study exhibited signs of minor affective disorders. Other findings noted include increased IgG antibodies in bipolar disorder patients, and possible association between neurotropic pathogens (such as influenzavirus and coronavirus) with mood disorders (although it is judged to be probably secondary to increased intestinal permeability). Furthermore, abnormalities of host-microbiota interactions or of gut-microbiota composition have been associated with central nervous system disorders, such as autism, anxiety, depression. The integrity of intestinal microbiota may be considered a potential therapeutic goal to treat these conditions. [NPIDs: gastrointestinal disorders, mood, gluten sensitivity, gluten, celiac, wheat, affective disorders, intestinal permeability, autism, anxiety, depression]

Skodje et al. (2018) investigated the effect of gluten and fructan (common component of gluten) separately in individuals with self-reported gluten sensitivity (gastrointestinal discomfort which improves after gluten withdrawal). In this double-blind crossover study, 59 participants, for whom celiac disease was excluded and who were on a gluten-free diet already, were randomly selected to go on diets containing either gluten, fructans, or placebo (concealed in muesli bars) for 7 days. Then, the groups were given a minimum 7-day washout period (to allow the symptoms induced by the previous challenge to resolve), before they were crossed over into a different group, and this was repeated until all 3 challenges were completed by the individuals (gluten, fructan, placebo). Symptoms were measured by Gastrointestinal Symptom Rating Scale Irritable Bowel Syndrome (GSRS-IBS) version, with higher scores indicating greater severity. The overall GSRS-IBS scores varied significantly between the gluten, fructan, placebo challenges, with mean values of 33.1 ± 13.3, 38.6 ± 12.3, and 34.3 ± 13.9, respectively (P = 0.04). The GSRS-IBS scores for bloating were also high in the gluten and fructan groups: mean scores of 9.3 ± 3.5, 11.6 ± 3.5, and 10.1 ± 3.7, respectively, during the gluten, fructan, and placebo challenges (P = 0.004). The overall GSRS-IBS score for participants consuming fructans was significantly higher than for participants consuming gluten (P = 0.049), as was the GSRS bloating score (P = 0.003). Twenty-four participants had the highest overall GSRS-IBS score after consuming fructan, 13 scored the highest after having gluten, while 22 also reported their highest scores after taking in the placebo. It was revealed there was no difference in GSRS-IBS scores between the gluten and placebo groups. However, this crossover study has discovered evidence that fructans induce gastrointestinal symptoms in individuals with self-reported non-celiac gluten sensitivity. [NPIDs: gastrointestinal disorders, gluten, gluten sensitivity, fructan, IBS, celiac]

Busby et al. (2018) believed removing gluten from the diet could be an effective treatment strategy for mood disorders in those with gluten-related disorders but was unsure of the directionality of the relationship between gluten and mood. Her team of researchers therefore performed a systematic review of prospective studies examining effects of gluten on mood symptoms in patients with or without gluten-related disorders and later carried out meta-analyses on the data. Three randomised controlled trials and 10 longitudinal studies were included in the review, adding up to a total of 1139 participants. The results revealed that a gluten-free diet significantly improved pooled depressive symptom scores and interestingly, there was no difference in mean scores between people with gluten-related disorders and healthy controls after one year. In addition, a blinded gluten challenge vs. placebo indicated those with non-coeliac gluten sensitive patients were more likely to see their symptoms worsen. This review supports the association between mood disorders and gluten intake in susceptible people, and may have provided a new research topic in the use of a gluten-free diet in individuals with mood disorders without gluten-related disorders. [NPID: gastrointestinal disorders, mood, gluten, depression, coeliac]

This 2020 study focuses on sugars and their possible link to irritable bowel syndrome (IBS). High quantities of sugar are a feature of the Western diet, which is one of the potential risk factors for IBS. Khan et al. investigated the effects of glucose and fructose on the development of colitis in two different types of mice (wild-type and Il10-/-). In wild-type mice, consuming either 10% glucose in drinking water or a high-glucose diet led to severe colitis. The Il10-/- mice that were fed high levels of glucose developed a worsened colitis compared to glucose-untreated Il10-/- mice. Short-term intake of high glucose or fructose did not result in inflammatory responses in healthy guts but greatly shaped the composition of the gut microbiota (increased abundances of mucus-degrading bacteria). More mucolytic enzymes meant erosion of the colonic mucus layer in sugar-fed wild-type and Il10-/- mice. But worsening colitis was not observed among mice treated with antibiotics or those kept in germ-free environments. This suggests that the changes in gut microbiota composition significantly influenced the sugar-triggered development of colitis. In addition to this evidence, increased colitis susceptibility was seen in germ-free mice after transferring the microbiota from sugar-treated mice. Overall, the data supports the theory that simple sugar consumption induces colitis in mice and enhances its development via modulation of gut microbiota. [NPID: mice, IBS, irritable bowel syndrome, gut, glucose, fructose, sugars, simple sugars, colitis, microbiota, bacteria, microbes, diet, nutrition]

This 2017 narrative review conducted a literature search of Pubmed and Google Scholar databases for terms relating to psychoneuroimmunology (a field of medicine interconnecting human biology and psychology) and pain related to the gut, central nervous system and human internal organs (visceral pain). The aim was to provide insight into pathophysiological mechanisms and suggest treatment options. The review showcases novel findings that may assist clinicians and scientists discover new targets and research information. Toljan & Vrooman (2017) identify the brain-gut axis as a prime clinical target for therapy in inflammatory bowel disease and functional gastrointestinal disorders although there are many components with this axis to be addressed in order for treatment to be effective. Based on the findings, the authors recommend a non-invasive approach with an aim of modulating the brain-gut axis components such as the psychological and neuroendocrinological status, microbiota, enteric nervous system, or immune cells (e.g. glial or mast cells) instead of the established single-target treatments. Clinical tools such as psychotherapy, prebiotics, probiotics, nutritional advice and non-label drugs are available. Low-dose naltrexone is a non-label drug which targets glial cells to reduce neuroinflammation and pain. Toljan & Vrooman (2017) believe there are evidence-based tools available right now that are under-exploited. [NPIDs: gastrointestinal disorders, digestion, gastrointestinal tract, gut microbiota, gut-brain axis, gut, visceral pain, IBS, microbiota, enteric nervous system, prebiotics, probiotics, naltrexone, neuroinflammation]