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Understanding Why Gut Health is Important to Immunity

Understanding Why Gut Health is Important to Immunity

Our bodies are naturally equipped with defenses to fight off invading microbes that may cause disease. It is an intricate system and involves both innate and adaptive immunity.

Innate Immunity – prevents intruders from entering.

It’s the first line of defence and is quick to respond to and destroy foreign invaders. It includes physical and chemical barriers including skin, tears, mucus, cilia, stomach acid, urine flow, friendly bacteria and white blood cells.[1]

Adaptive Immunity – is mediated by B & T lymphocyte cells.

If pathogens are able to get past the first line of defence and an infection develops, the second line of defence becomes active. This includes cells, tissues and organs that work together to attack pathogens and protect the body.[2]

Kate MacDonald simplified it best in her article The Immune Response on the website, Let’s Talk Science.

  • Special cells called dendritic cells are the point of communication between innate and adaptive immunity. When macrophages sound the alarm, dendritic cells are part of the crew that responds. They travel to the site of infection and break off small parts of the pathogen. They carry these parts to your lymph nodes, where adaptive immunity begins.
  • The adaptive immune response involves B and T cells which are specialized white blood cells called lymphocytes – B cells are found in the blood. Their main function is to produce antibodies to counteract the antigens that get into the body. To do this, they work with the T cells.
  • In the lymph nodes, the dendritic cells search for T cells. Your body makes millions of different T cells. Each type of T cell can recognize a different type of pathogen. This means your body can combat almost every invader, even the ones it’s never seen before.
  • In the lymph nodes, the T cells are fully mature, but have never encountered the pathogen they’re supposed to fight. These cells are essentially asleep. The dendritic cells’ job is to wake them up and bring them to the pathogens.
  • Memory T cells remember pathogens you’ve seen before. They help your body launch a quicker, more effective defence the next time around.
  • Cytotoxic (“cell-killing”) T cells destroy any of your own cells that have been infected with a virus.
  • T helper cells help other cells, such as B cells, often by releasing proteins called cytokines. These proteins bind to other cells in your body and tell them how to strengthen the immune response. For example, a cytokine might activate a B cell, which would make antibodies against the invading pathogen. When you’re dealing with a bacterial infection from a cut finger, a T helper cell is one of the more useful kinds of T cells.
  • T regulatory cells are the police of the adaptive immune system. They shut down the attack launched by other immune cells once the pathogen has been cleared. This stops the immune response from getting out of control.
  • Usually, T cells can eliminate a bacterial infection just days after they’ve been activated. At this point, your body can stop fighting, and you’ll start to feel better.[3]

Bacteria in our bodies teach our immune systems how to distinguish between dangerous invaders and harmless ones and they help to regulate our host immune responses.[4] There are an estimated 39 TRILLION bacteria that reside inside the gut microbiome alone.[5]  With this understanding, we can appreciate why good gut health is so important to a healthy immune system.

Here are some helpful tips to keep your gut and immune system happy:

  • Include lots of vegetables, grains, and beans in your diet which feed a positive gut environment.[6]
  • Avoid processed, high sugar and pre-packaged foods. Studies have determined that processed foods reduce the number of gut microbiota and influence the immune system’s ‘readiness’ and the body’s defense against pathogenic bacteria.[7]
  • Get a good night sleep – Sleep deprivation disturbs the functional rhythm of immune cells.[8] Aim for 7-9 hrs/night.
  • Avoid stress as much as you can. High stress situations which trigger the fight-or-flight response could be beneficial to the immune system, but chronic stress can negatively affect it and be detrimental to your health.[9]
  • Take Renew Life® Ultimate Flora® Critical Care 50 Billion multi-strain probiotic formula to support intestinal and gastrointestinal health. It comes in both refrigerated & shelf stable formats for user preference. Probiotics interact with immune cells and shift T-helper cell balance. They are also antagonistic against potentially pathogenic organisms.[10]
  • Include Renew Life’s® IntestiNEW®, an easy-to-mix powder formulation including L-Glutamine and N-Acetylglucosamine along with soothing herbal ingredients to help support a healthy intestinal lining.
By: Caroline Farquhar, RHN, EMP, BA, National Training Manager at Renew Life®
[1] [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. The innate and adaptive immune systems. [Updated 2020 Jul 30]. Available from:
[2] ibid
[3] MacDonald K. (2019). The Immune Response. Available: Last accessed 15 Nov 21.
[4] Yan F, Polk DB. Probiotics and immune health. Curr Opin Gastroenterol. 2011;27(6):496-501. doi:10.1097/MOG.0b013e32834baa4d
[5] Looi, M. (2020). The human microbiome: Everything you need to know about the 39 trillion microbes that call our bodies home. Available: Last accessed 8 Nov 21.
[6] Tuohy KM, Fava F, Viola R. ‘The way to a man’s heart is through his gut microbiota’–dietary pro- and prebiotics for the management of cardiovascular risk. Proc Nutr Soc. 2014 May;73(2):172-85. doi: 10.1017/S0029665113003911. Epub 2014 Feb 4. PMID: 24495527.
[7] Olshansky, C. (2021). One Major Side Effect of Eating Too Many Processed Foods, Says New Study. Available: Last accessed 15 Nov 21.
[8] Bollinger T et al. Sleep-dependent activity of T cells and regulatory T cells. Clinical & Experimental Immunology. 2009;155(2):231-238.
[9] Salleh MR. Life Event, Stress and Illness. The Malaysian Journal of Medical Sciences. 2008;15(4):9-18
[10] Yan F et al. Probiotics and immune health. Current Opinion in Gastroenterology. 2011;27(6):496-501.
Renew Life Ultimate Flora Probiotics

About the Author: Caroline Farquhar R.H.N., E.M.P., B.A.

Caroline Farquhar

Specializing in digestive care and cleansing, Caroline has been educating audiences through seminars, TV and radio appearances across the country on the topic of how to achieve better health naturally. Caroline has written and published articles for magazines and websites, has created educational programs and taught at the Canadian School of Natural Nutrition.