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  • Richard R. Fay, DC

Child and Adult: Comparing Immune Systems

Immunity and Survival

Humans are social creatures, often eating for pleasure in group settings. While humans may love and appreciate the process and the feelings associated with eating food, there is little thought about the immune and survival advantages provided by the macronutrients and micronutrients that make up our food. We provide support for your family’s immune health. We have solutions for boosting adult immunity as well as children over four years of age. Contact us for details!

Children are no strangers to eating for pleasure; sweetness dominates the taste preferences of most. It is important to understand the biological processes that promote immune health in children versus adults. How do modern food choices affect a child’s immune biology?

A child’s basic immunology is imperfect up until approximately five years old. Until this point, a child’s immune system has not adequately developed to respond adaptively (via antibodies) to new invading pathogens. This leaves them at risk for overwhelming infectious disease.

History has proven this to be true with excessive death rates in the very young and the very old before the advent of vaccinations and sanitation. However, despite this, the best childhood health outcomes are based on providing the immune system with nutrients for optimal function. This includes breastmilk and diverse, whole food-based nourishment.

The Developing Immune System: Tolerance is Key

From the very beginning of life, a child’s body must learn to tolerate the outside environment through specific immune events. Antigen presenting cells differentiate between harmless and harmful particles that enter the body.

For example, a peanut protein versus a dust mite protein or a harmful pneumococcal bacterium. In the first two years of life, the immune system is repeatedly bombarded with foreign protein antigens until it has seen and responded to all in either a pathogenic form or a tolerant form. This process primes the immune system to function appropriately throughout their lives. Children explore with their mouths and that proclivity supports this process. Nutrients also promote tolerance, primarily vitamins A and D, zinc, and fiber. 1-4

Child vs. Adult Immune System

In comparison, the average adult immune system has fully developed tolerance. This allows it to respond appropriately to defend against pathogens at all times. When we get older, the function of T helper cells is and antigen presenting cells are reduced. This ‘weakens’ our immune system.

By two years of age, children develop fully functional innate immune pathogen sensing and killing systems. 5 The innate immune system is a sensing system that recognizes patterns of protein fragments that appear dangerous and rapidly mounts a local response to fight them off. This innate system deploys pattern recognition receptors all over the child’s body to recognize the abnormal pattern of a pathogen and locally kill it. These dead pathogens are then presented to the adaptive immune system. This process ultimately develops long lasting antibodies and memory to this pathogen, making subsequent encounters less problematic.

The process of innate pathogen killing is much more profound in a child versus an adult, as children have naïve adaptive immunobiology before initial exposure to a pathogen. Consuming the precursor macronutrients and micronutrients for effective innate immune activity is critical for a child’s health. Once a pathogen has been seen and thwarted, the child’s future pathogen-specific immune response mirrors that of the adult through memory B and T cell activity.

Immunological Fade

Pathogen memory is the key attribute of adaptive immunity that helps us survive infection from a pathogen. The systems that protect a child and young adult begin to fade in late adulthood. This immunological fade can occur in the younger cohort for many of the same reasons as the elderly other than cellular senility based purely on age:

  • Macronutrient excesses

  • Micronutrient deficiencies

  • Excessive chemical exposures

  • Sedentary behaviors

  • Dietary and pharmacologically induced intestinal and pulmonary microbiome damage

If we can reduce inflammation, we can mediate many of these effects.

A modern diet, which includes a large number of processed foods, is a major problem for immune health in both adults and children. Insulin resistance is a primary driver of hyperglycemia (high blood sugar), and hyperlipidemia (fat in the blood), and it is mediated by the chronic and excessive consumption of free fatty acids primarily coupled to a sugar gradient of glucose and/or fructose. A classic example would be a fast-food meal: a cheeseburger, French fries, and a 16-ounce soda. 7,8 The most important variables appear to be frequency and volume of fatty acids and sugars consumed, as chronic consumption may lead to the development of a positive calorie flux.

Over many years, diet-induced chronic metabolic changes usher in a period of immune dysregulation, notably decreasing effective pathogen killing and increasing metabolic disease risk. 9,10 Inflammation actually reinforces the dietary induced insulin resistance metabolic derangement pathway to repeat itself in a continuous cycle.

Micronutrient insufficiencies occur commonly in modern children and adults. As micronutrients are the cofactors for most cellular enzymatic reactions in the body, the consequences of insufficiency are slowed protein production, deranged immune cell function, and disrupted immune cell signaling pathways critical to immune regulation among others. Vitamins A, B, C, D, and E, zinc, iron, selenium, magnesium, and copper play the greatest roles. 11

Each of these micronutrients is involved in different and also cooperative events in the immune system. These micronutrients are utilized best when consumed as whole foods. The greatest difference between the adult and the child’s immune system is the time course by which lifestyle behaviors have affected our adult immune system.

We can provide solutions to support your immune system as well as your children’s immune system. We have products formulated to boost the adult immune system and an easy daily chewable supplement for children prone to upper respiratory infections. Contact us for details!


  1. Tan, J., McKenzie, C., Vuillermin, P. J., Goverse, G., Vinuesa, C. G., Mebius, R. E., Macia, L., & Mackay, C. R. (2016). Dietary Fiber and Bacterial SCFA Enhance Oral Tolerance and Protect against Food Allergy through Diverse Cellular Pathways. Cell reports, 15(12), 2809–2824.

  2. Veldhoen, M., & Brucklacher-Waldert, V. (2012). Dietary influences on intestinal immunity. Nature reviews. Immunology, 12(10), 696–708.

  3. Chinthrajah, R. S., Hernandez, J. D., Boyd, S. D., Galli, S. J., & Nadeau, K. C. (2016). Molecular and cellular mechanisms of food allergy and food tolerance. The Journal of allergy and clinical immunology, 137(4), 984–997.

  4. Gombart, A. F., Pierre, A., & Maggini, S. (2020). A Review of Micronutrients and the Immune System-Working in Harmony to Reduce the Risk of Infection. Nutrients, 12(1), 236.

  5. Simon, A. K., Hollander, G. A., & McMichael, A. (2015). Evolution of the immune system in humans from infancy to old age. Proceedings. Biological sciences, 282(1821), 20143085.

  6. Mokarizadeh, A., Faryabi, M. R., Rezvanfar, M. A., & Abdollahi, M. (2015). A comprehensive review of pesticides and the immune dysregulation: mechanisms, evidence and consequences. Toxicology mechanisms and methods, 25(4), 258–278.

  7. Nowotny, B., Zahiragic, L., Krog, D., Nowotny, P. J., Herder, C., Carstensen, M., Yoshimura, T., Szendroedi, J., Phielix, E., Schadewaldt, P., Schloot, N. C., Shulman, G. I., & Roden, M. (2013). Mechanisms underlying the onset of oral lipid-induced skeletal muscle insulin resistance in humans. Diabetes, 62(7), 2240–2248.

  8. Reaven G. M. (1988). Banting lecture 1988. Role of insulin resistance in human disease. Diabetes, 37(12), 1595–1607.

  9. Villarreal-Calderón, J. R., Cuéllar, R. X., Ramos-González, M. R., Rubio-Infante, N., Castillo, E. C., Elizondo-Montemayor, L., & García-Rivas, G. (2019). Interplay between the Adaptive Immune System and Insulin Resistance in Weight Loss Induced by Bariatric Surgery. Oxidative medicine and cellular longevity, 2019, 3940739.

  10. Patel, P. S., Buras, E. D., & Balasubramanyam, A. (2013). The role of the immune system in obesity and insulin resistance. Journal of obesity, 2013, 616193.


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