Food intolerance and sensitivity

Although it is known that people with autism spectrum disorder (ASD) often have food allergies, the limited data on its prevalence is addressed in this 2019 study. This present study used surveys to ask parents if their children had either food allergies or autism. The kids were from the U.S. and aged between 2 and 17 years. Among this nationally representative sample of 53,365 children, the prevalence of autism was 1.7% (905), while food allergies were reported in 5.6% of the subjects. Analysis of this data revealed that food allergies were almost 2.5 times more common in youths with ASD (prevalence of 13.1%) than in those without ASD (5.4%). To conclude, this article demonstrates that food allergies are found to frequently co-occur with autism spectrum disorder. [NPID: autism, autism spectrum disorder, ASD, food allergies, allergies, sensitivity, diet, U.S., US, Americans, children]

This 2019 study focuses on inflammation in the context of major depressive disorders (MDD) since systemic chronic low-grade inflammation has been previously linked with the progression of MDD. But it is unclear whether pro-inflammatory cytokine levels are excessively high before the first episode of MDD. Thus, Tao et al. recruited 184 adolescents who were experiencing their first episode of depressive disorder, and measured their blood levels of various biomarkers (including high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), IgE). These readings were then compared to those of healthy individuals who also enrolled in this study as control subjects. There was no extraordinary difference in the hs-CRP or TNF-α levels between the two groups, but the histamine concentrations of the patients (with depressive disorder) were significantly higher than those of the controls. Furthermore, a markedly higher percentage of the patient group tested positive for food antigen-specific immunoglobulin G (IgG antibodies react to the presence of very specific food antigens), compared with the control group. Over 80% of the patients in this study showed prolonged food intolerance with increased levels of histamine, leading to hyperpermeability of the blood–brain barrier (which has been associated with the pathogenesis of major depressive disorder). It was therefore concluded that having high blood histamine readings for an extended period could be a risk factor for depressive disorders. The blocking of histamine synthesis through antihistamine use may represent a novel strategy for depression treatment. [NPID: inflammation, depression, major depressive disorder, MDD, inflammatory, histamine, food intolerance, adolescents, antihistamines]

This 2018 study tests the hypothesis that the intestinal microbiome of children with food allergies may be significantly different to those found in genetically similar non-allergic children and age-matched controls. The objective of this study was to characterize the microbiota found in fecal samples to identify the bacteria taxa that may affect expression of food allergy. Stool samples were taken from children with IgE-mediated food allergies, siblings without food allergy, and non-allergic controls. Overall, this study recruited 22 child participants with food allergies, 25 siblings without food allergies, and 21 non-allergic control subjects. Compared to their siblings and the control group, the food-allergic sample group had higher abundances of microbes within the Clostridia class and Firmicutes phylum (such as Oscillobacter valericigenes, Lachnoclostridium bolteae, Faecalibacterium sp.). Whereas non-allergic siblings were found to have a larger population of the Alistipes sp. bacteria. Moreover, the scientists identified differences in specific Clostridia that may trigger the separation of the allergic from the siblings and controls. There were important differences in microbiome signatures discovered in the feces of food-allergic children, siblings, and healthy children. Both genetic and environmental factors appear to contribute to the manifestation of food-allergic disease. [NPID: gut microbiome, gut microbiota, gut bacteria, gastrointestinal, GI, food allergies, allergies]

According to this 2020 article, food allergy seems to be related to low exposure to a diverse range of microbiota during the first few years of life. Encountering microbes leads to the colonization of the gastrointestinal tract by microbes that can help us and provide the host with benefits. These commensal microorganisms are crucial for the development of a balanced and tolerant immune system. Sequencing technology is now available, which has already assisted studies in investigating the gut microbiota and the bacterial-derived metabolites. There has been considerable research conducted on microbiota’s role in allergies, but the importance of food allergies was only recently highlighted. Human studies have identified a link between dysbiosis (imbalance in the bacteria community) and the pathways thought to be involved in the development of food allergy. Meanwhile, animal studies have indicated that specific microbial species in the gut can alter the host’s immune response, which may be capable of desensitizing food allergies. This present paper reviews the role of the gut microbiota in food allergy, and discusses the influences of environmental factors, as well as potential prevention and management strategies for food allergies. [NPID: food allergy, food allergies, allergies, microbiota, microbes, microbiome, gut, gastrointestinal, GI, immune function, immunity, bacteria, review, environment, environmental]

This 2016 article explains that lifestyles and exposure to various environmental factors may be responsible for the rapid rise in childhood allergies reported in Westernized countries. Microbiological studies have already demonstrated that altered compositions in gut microbial communities during very early life may be connected to the presence of food allergies during childhood. Moreover, infants who exhibit more severe multisensitization to food or airborne allergens are significantly more likely to suffer from asthma during childhood. Thus, it has been hypothesized that abnormalities in the early-life gut microbiome composition (and microbial function) driven by lifestyle and/or the environment may play an important and mediatory role in childhood allergic asthma. This theory has been supported by animal studies. The exposures to certain environmental microbes associated with allergy protection in humans were also found to keep mice safe from airway allergies. In addition, short-chain fatty acids derived from gut microbiomes and produced from a high-fiber diet conferred protection against allergies. This paper explores the connection between the gut and the airways, and its relevance to childhood allergies. [NPID: gut microbiome, gut microbiota, allergies, allergy, environment, environmental, lifestyle, children, child, infants, fatty acids, bacteria, airways, asthma, food]