Maintaining immune system homeostasis

Targeting the proper patient pathways with nutritional, supplemental and whole-food support

Homeostasis describes the status of the body when physiology is running smoothly. It is the self-regulating process by which the body maintains stability while adjusting to accommodate changing external conditions.¹ This ongoing process is easy to take for granted, but day-to-day living requires constant adaptation to keep internal body conditions stable.

Because the ideal range for stability can be quite narrow, especially for body temperature and pH, maintaining homeostasis involves several layers of complex regulatory mechanisms.¹ Homeostatic mechanisms operate at every level, requiring that various inputs, stimuli and regulatory mechanisms from each level be integrated throughout the entire body in order to maintain homeostasis. Equilibrium is critical for a healthy body, as the lack of ability to maintain homeostasis can lead to imbalance within multiple systems.¹

Homeostasis in the immune system

The immune system is complex and intricate, and as such, homeostasis of the immune system requires a very fine balance between various cells and states. It relies on various inputs and responders in the body in order to effectively protect against pathogens while allowing harmless, bioactive compounds to carry out their functions. As with many aspects of human physiology, more is not always better. Inflammatory activity is required at times, but too much can have serious consequences.² Similarly, oxidative species are important cellular messengers but too much can lead to oxidative stress. Oxidative stress can cause cellular damage and death. The immune system relies on homeostatic processes at every level to keep its components in balance and working smoothly.

Specifically, immune homeostasis occurs when there is a balance between effector immune cells and regulatory immune cells.² Together, they maintain a balance between eliminating pathogens by stimulating the immune system and preventing excess inflammation when there is no active threat present.² When immune homeostasis is disrupted, improper inflammatory cues can arise, either allowing a conducive environment for disrupters to flourish or improperly attacking components of the body.²

Maintaining immune system homeostasis involves achieving homeostasis in all the tissues involved in the immune response. They must work together to mount an appropriate response, including tissues that can be overlooked. For example, adipose tissue is home to many immune cells, including regulatory T cells and macrophages, both of which are involved in immune homeostasis.³ Maintaining homeostasis in adipose tissue is critical in preventing excessive inflammation, which if left unchecked can lead to metabolic issues.³

The gastrointestinal (GI) tract is vital to immune homeostasis, working to aid in the immune response through multiple mechanisms. First, the GI tract is home to bacteria that, when properly balanced, help maintain the health of the body. A healthy, diverse gut microbiome supports homeostasis and overall health by enhancing immune function and producing metabolites and signaling molecules.^4,5 When populations in the gut become off-balance, this imbalance can lead to acute and chronic conditions which can then further promote gut dysbiosis and negatively affect immune homeostasis.⁴

The GI tract also physically separates potential pathogens and disrupters from the rest of the body. The presence of gut-associated lymphoid tissues (GALT) helps protect the intestines and the rest of the body from the near-constant presence of antigens and microbes in the intestinal tract.⁶ Homeostasis in the GI tract includes balancing tolerance for external factors with mounting an inflammatory response to destroy potentially harmful substances.⁶ When the balance shifts to either side, it can cause issues in the intestines but also the entire body.⁶ Because the GI tract is exposed to many more factors than other systems of the body, its separation from the systemic immune system is critical.⁶

Nutritional support for immune system homeostasis

Therapies that support homeostasis should target pathways that work with natural homeostatic mechanisms, rather than against them.¹

Dietary interventions and nutritional support are effective ways to work with the body to support homeostatic mechanisms and the immune system. In general, consuming a balanced, diverse diet that includes abundant fruits and vegetables can support both homeostasis and immune system health. Additionally, clinical studies have demonstrated effective interventions throughout the life span.⁷

Micronutrients

Micronutrients are involved in every stage of the immune response and therefore can support immune homeostasis.⁸ Vitamins involved in immune homeostasis include vitamins A, B₆, B₉, B₁₂, C, D and E; minerals involved are zinc, iron, copper, selenium and magnesium.⁸ These micronutrients have many roles in maintaining immune system homeostasis, including:^7,8

Supporting the integrity of physical barriers
Modulating oxidative bursts and inflammation
Exhibiting antimicrobial activity
Regulating cytokine production
Supporting immune cell proliferation, differentiation and function
Aiding in antibody production and function

While these micronutrients have unique functions in the body, they also work together synergistically to further enhance homeostasis.⁸ For example, T-cell activity is influenced by vitamin E, vitamin B₆ and zinc, but there may also be a synergistic effect between vitamin A and zinc which can then influence T-cell activity.⁸

In order to obtain the immuno-modulating effects of these vitamins and minerals, intake may need to exceed current recommended dietary allowances.⁸ Individuals with suboptimal levels may benefit the most from increased intake, and certain situations such as infections, stress or pollution may deplete stores within the body, further increasing the requirements.⁸ It is important to obtain sufficient levels because even marginal deficiency of certain micronutrients can impair immunity and increase susceptibility to infection.^7,8

Antioxidants

Antioxidants are important components of the immune response, helping to protect cellular membranes from damage induced by free radicals that can occur when the body is fighting off a pathogen.⁸

Glutathione is a powerful antioxidant in the body, helping balance oxidative stress, regulating cellular events and supporting nutrient metabolism.⁹ Other antioxidants include vitamin C and vitamin E as endogenous antioxidant defense systems.⁸Many fruits and vegetables contain glutathione, vitamin C and vitamin E, including almonds, avocadoes, spinach and cruciferous vegetables.

Protein

Protein is a macronutrient that supports immune homeostasis through its delivery of amino acids. Amino acids are required for the biosynthesis of many immune proteins, including cytokines and antibodies.⁷

Because these immune proteins mediate the immune response, maintaining a readily-availably supply can help when they are needed.⁷ Specific amino acids are also important in various aspects of the immune response. For example, arginine and methionine are involved in the synthesis of polyamines which regulate cellular proliferation, inflammation and pathogen recognition.⁷ Methionine is also a component of glutathione, an important antioxidant.⁷

Gut support

Strengthening and supporting the bacteria of the gut microbiome via probiotics and prebiotics can significantly improve GI health, which can in turn support healthy immune homeostasis.

Probiotics are living bacteria that can colonize the gut and correct imbalances in the gut microbiome by increasing populations of good bacteria, inhibiting adhesion of pathogens to intestinal cells, and synthesizing antibacterial substances and vitamins to promote a healthy gut environment.¹⁰ Prebiotics feed bacteria that reside in the gut, providing nutrients to beneficial bacteria which can benefit the entire body.

Fiber from the diet can serve as a prebiotic to some bacteria, enabling the production of beneficial metabolites to feed intestinal cells and beneficial bacteria.¹¹ Additionally, 2’-fucosyllactose (2’-FL), a human milk oligosaccharide, can act as a prebiotic specifically feeding Bifidobacteria, which benefits both gut and immune health.¹²

Immune support from whole-food sources

The best support for immune homeostasis comes from a whole-food diet, abundant in fresh fruits and vegetables.¹³ Whole foods provide fiber in addition to immune-supporting micronutrients, enabling the body to obtain various bioactive compounds required for maximal immune health.

Many fruits and vegetables also deliver antioxidants and phytonutrients that can exert beneficial effects in the GI tract, immune system and throughout the entire body.¹³ Together, the synergistic components of whole foods can support multiple facets of the immune response and help maintain homeostasis.

The immune system is a complex, intricate system that works continuously to keep the body healthy and safe from potentially dangerous invaders. The GI tract is an important part of the immune system, although it is often overlooked. A healthy diet rich in fruits and vegetables can provide essential micronutrients to directly support the immune system and complement dietary compounds that support the immune system indirectly by enhancing gut health.

KERI BARRON, PhD, is the scientific nutrition writer for Standard Process Inc., located at the Nutrition Innovation Center in Kannapolis, N.C. Her work involves creating educational materials and translating scientific articles for audiences to support health and wellness. She has a B.S. in Nutritional Biochemistry and Metabolism and an M.S. in Nutrition from Case Western Reserve University in Cleveland, Ohio. She continued her studies at the Nutrition Research Institute, a remote campus of the University of North Carolina at Chapel Hill, earning a PhD in Nutrition. She is a member of the American Society for Nutrition and is passionate about nutrition education.

References

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