Gut Health and the Immune Response

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The immune system, which is primarily in the gut, is influenced and actually taught by the gut microbiome. The microbiome helps determine the vitality of the immune system, as well as its 'set-point' for the pro-inflammatory response to infection.

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Much of the body’s immune response depends upon the gastrointestinal microbiome, and understanding its complexities and potential therapeutic targets is essential, particularly in times of stress and/or when risk of infection increases. The composition of the gut microbiota is under the surveillance of the mucosal immune system.1 Studies suggest that the maintenance of a healthy gut microbiome is inseparable from host health;1 there is, in fact, a bidirectional relationship between the gastrointestinal microbiome and the innate immune system.2 Inflammation, which is caused by abnormal immune responses, influences the balance of the gut microbiome, resulting in intestinal diseases.2 Likewise, supporting a balanced intestinal microbial community is essential for the integrity of the immune system, for the prevention and response to infections, and for recovery from illness.1,2 The microbes and their metabolites influence physiological function (particularly metabolism), local mucosal homeostasis, inflammation, and interactions between multiple body systems.1,3-5 Therefore, an imbalanced intestinal microbiota may have system-wide effects and contribute to immune health.6

 Intestinal homeostasis is maintained by a complex interplay among the epithelium, immune factors, and the microbial flora.7 The most recent research identifies cytokines as crucial moderators in the maintenance of intestinal homeostasis. These small proteins secreted in the gut support intestinal homeostasis by governing key cellular processes like cell death, proliferation, molecular transport, and inflammatory responses against pathogens. Cytokines can modulate the division of epithelial cells and assign appropriate immune cells to establish feedback loops.7

Changes in the microbial composition induced by diet, alcohol, or antibiotic intake, or due to pre-existing genetic factors, can lead to dysbiosis in the gut and deregulation of cytokine signatures.7 Associative links exist in the research between alterations in the microbiome and immune health, as well as some chronic immune/metabolic disorders.8 Gut microbiota alterations due to unhealthy lifestyle factors and dietary triggers may contribute not only to inflammation, but also to intestinal permeability; dysbiosis of gut microbiota has been closely linked to several diseases, such as obesity, type 2 diabetes, hypertension, necrotizing enterocolitis, and inflammatory bowel diseases.1,2Healthy lifestyle factors, including a diversified diet, limited consumption of processed and refined foods, and consumption of adequate dietary fiber, may all promote a healthy microbiome.1,9 Foods and nutrients that potentially boost immune function also tend to promote gut health. For example, consuming a diverse array of fruits and vegetables rich in antioxidants, anti-inflammatory nutrients, and phytochemicals may reduce oxidative stress, support the liver to promote efficient biotransformation and detoxification, and boost overall immune system function.10-14 These same fruits and vegetables also contain soluble fibers that “feed” the commensal microbial community in the colon to optimize gut balance and health and insoluble fibers that assist in the efficient processing and elimination of waste from the intestinal tract.15

Supporting a healthy microbiome is a cornerstone of functional medicine and essential for strengthening immune responses and improving overall health. Personalized therapeutic interventions that focus on modifiable lifestyle factors may optimize immune system function while supporting gut health. Such lifestyle modifications may include the following:

  • Therapeutic food plans
  • Multi-strain probiotic supplementation
  • Adequate sleep and sleep quality
  • Movement and exercise plans
  • Reduction of dietary triggers and toxic exposures
  • Stress management or transformation

Implementing personalized treatment approaches that support the health and balance of the intestinal microbiome may be essential to not only strengthen resilience for high-risk chronic disease patients, but also to optimize immune function and disease prevention for healthy patients.

Gut microbial composition is a key factor in the cross-talk between the gastrointestinal microbiome and the immune system. Explore the latest research on this topic at the upcoming Annual International Conference. In the aptly titled lecture “The Gut Immune Connection—And What Role Your Microbes Play in It,” Emeran Mayer, MD, will focus on alterations within the brain-gut microbiome system and their role in chronic inflammatory and functional diseases.

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