The Link Between Probiotics and Immunity

You’re likely familiar with the role that probiotics play in gut health. But did you know probiotics have also been extensively researched for their benefits in immune health?

The gut is home to 70-80% of the body’s immune cells, and a healthy gut microbiome plays a vital role in the development of a child’s immune system ^(1,2).

A child’s immune system develops over many stages of their life. While a child’s immune system is developing, it is very common for kids to experience 6 to 12 respiratory tract infections per year in the first few years of life. For parents, this means it can seem like their child is sick all the time ⁽³⁾.

This usually coincides with the time when a child is starting day care and school or attending anywhere that they are suddenly exposed to large groups of other children.

Young children may have low resistance to infection, as they may have had little or no previous contact with the viruses that cause illnesses like the common cold. It is useful to know that children can get sick much more quickly than adults ⁽⁴⁾.

The immune system is an integrated system of cells, tissues and organs that has a specialized role in protecting from foreign invaders – notably illness causing bacteria, viruses, and fungi.

The gastrointestinal system is one of the body’s first lines of defence. It functions as a barrier, protecting the body from foreign invaders which are found in the environment around us, from contact with others, or can be ingested from foods and drinks. Probiotic’s can assist and support optimal mucus membrane immunity, a first line of defence for overall immunity.

The ability of the gut to protect the body from immune threats depends on the establishment of a healthy microbiome. Probiotic supplementation has been shown to regulate gut-mediated immune responses, particularly through helping to control inflammation and strengthening the gut’s barrier function ⁽⁵⁾.

A healthy diet, including a wide range of essential nutrients is vital to support a healthy immune system, and interestingly, it also influences microbiome health. A healthy gut microbiome relies not only on good bacteria, but also a diverse diet that incorporates a wide range of these essential nutrients ^(6,7).

Vitamins A, C, D and E, as well as iron and zinc to name a few, are essential for immune health. Poor nutritional status and nutrient deficiencies can decrease the body’s immune defenses, making it easier for illness causing bacteria and viruses to take hold. It can also increase the amount of time the body needs to recover ⁽⁸⁾.

Gut health and nutrient absorption work hand in hand. Just like essential nutrients contribute to a healthy gut microflora, beneficial bacteria and a healthy microbiome can aid nutrient absorption from food ⁽⁵⁾. Reduced intake and absorption of essential nutrients can disrupt gut health and the body’s gastrointestinal immune system.

Supplementation with probiotics improves the balance between the “good” and the “bad” bacteria. The types of bacteria most commonly used and thoroughly studied are bifidobacteria and lactobacilli ⁽⁵⁾.

Lactobacillus rhamnosus GG is one of the most highly researched probiotic strains. In children it has been shown to help reduce the occurrence of symptoms of upper respiratory tract infections, like symptoms of the common cold^(9,10).

References:

1. Arrieta, M, Stiemsma, L, Amenyogbe, N, et al. (2014). The intestinal microbiome in early life: health and disease. Frontiers in Immunology, 5. DOI: 10.3389/fimmu.2014.00427
2. Furness, J, Kunze, W & Clerc, N. (1999). Nutrient tasting and signalling mechanisms in the gut. II. The intestine as a sensory organ: neural, endocrine, and immune responses. The American Journal of Physiology, 277 (5). G922-G928.
3. The Royal Children’s Hospital Melbourne (2020). Viral Illnesses. Accessed 15 August 2022 < https://www.rch.org.au/kidsinfo/fact_sheets/viral_illnesses/ >
4. Australian Government Department of Health – Pregnancy, Birth & Baby (2021). Colds and flu in babies and children. Accessed 15 August 2022 < https://www.pregnancybirthbaby.org.au/colds-and-flu-in-babies-and-children >
5. Isolauri, E, Sitas, Y, Kankaanpaa, P, et al. (2001). Probiotics: effects on immunity. The American Journal of Clinical Nutrition. 73 (2). 44S-450S.
6. Heiman, M & Greenway, F. (2016). A healthy gastrointestinal microbiome is dependent on dietary diversity. Molecular Metabolism, 5. 317-320.
7. Mach, N & Clark, A. (2017). Micronutrient Deficiencies and the Human Gut Microbiota. Trends in Microbiology, 25 (8). 607-610.
8. Maggini, S, Pierre, A & Calder, P. (2018). Immune Function and Micronutrient Requirements Change over the Life Course. Nutrients, 10 (10). DOI: 10.3390/nu10101531
9. Liu, S, Wei Hu, P, Du, X, et al. (2013). Lactobacillus rhamnosus GG Supplementation for Preventing Respiratory Infections in Children: A Meta-analysis of Randomized, Placebo-controlled Trials. Indian Pediatrics, 50. 377-381.
10. Hatakka, K, Savilahti, E, Ponka, A, et al. (2001). Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial. BMJ, 322. 1-5.