Boosting your toddler’s immune system? Start today!

Boosting your toddler’s immune system can start today.  Did you know that in the first 3 years of life your child is building most of their microbiome? To simplify understanding I will use “gut flora” interchangeably with microbiome. Building a healthy gut flora in conjunction with eating nutritious foods helps to build and maintain a healthy immune system. It starts now.

Gut flora’s evolution and the Immune System

It is estimated that at age 3, a child’s gut flora has reached an important level of its maturation¹.  Infants ingest a range of beneficial organisms during vaginal birth² and breastfeeding. This colonisation of the infant’s gut informs the immune system which trains itself to recognise and fight harmful germs. 

When mothers can breastfeed, they further help enrich their infant and toddler’s gut flora. Breast milk provides friendly bacteria that further populate the gut flora. It also contains oligosaccharides³ (HMO) a prebiotic which feeds beneficial bacteria, as well as immunoglobulin. Both compounds (HMO and Ig) help seal the lining of the intestine so it prevents the passage of harmful germs and toxins.

When solids are introduced, dietary diversity sky rockets and in turn so does the microbiome growth toward what will be a stabilised and varied adult like gut flora.

Toddlers can continue to harbour a healthy gut flora based on the nutrition they receive. Optimal nutrition for a healthy microbiome can be summed up as follows: 

Live cultures

Natural foods that contain live cultures help replenish the gut flora with useful bacteria. Yoghurt is a well-known source of live bacteria and has been associated in many cultures with longevity⁴. Kefir is more tangy and liquid than yoghurt. It contains bacteria as well as yeast. Yoghurt and kefir have been consumed for hundreds of years and are an easy addition to a toddler’s diet. If your toddler is lactose intolerant or allergic to milk, you may find alternatives in the form of:

  • lactose free yoghurt
  • coconut yoghurt
  • tempeh
  • miso
  • sauerkraut
  • kimchi
  • kombucha
  • pickles etc, 

Note: if the product is pasteurised or heated there is no beneficial bacteria left in it. Always check the label for live cultures. 


Probiotics are purchased over the counter, as capsules or in a powdered form. They may contain different strains and amounts of bacteria. They are often recommended when a child has been given antibiotics. It can be useful to talk about them with your GP.

Live bacteria and probiotics need prebiotic fibre

If there is no fibre for it to feed on, bacteria cannot survive. Scientists established that a western style diet, poor in fibre, negatively impacts the gut flora variety. The proliferation of less beneficial bacteria creates a harmful imbalance also known as dysbiosis.  Dysbiosis has been implicated in a wide range of diseases. 

Prebiotic fibre

Serving a fibre containing food with each meal helps your toddler’s gut flora. Fibre is wonderful but prebiotic fibre is optimal. To read more about high fibre, high prebiotics diets click here.

High prebiotic content food (source: Monash University, Harvard School of Public Health).

  • Vegetables: sweetcorn, peas, beetroot, asparagus, snow peas, garlic, onion, leek, shallots, spring onion, fennel bulb,  cabbage, chicory, Jerusalem artichokes, seaweed.
  • Legumes: chickpeas, lentils, red kidney beans, baked beans, soybeans.
  • Fruit: bananas, nectarines, white peaches, watermelon, grapefruit,  pomegranate, custard apples, persimmon, tamarillo, rambutan, dried fruit (eg. dates, figs).
  • Grains: barley, rye, pasta, gnocchi, couscous, wheat bran, wheat bread, oats.
  • Nuts: cashew, pistachio nuts, flax seeds.

Essential Nutrients and the Immune System

A good nutritional status is necessary to help maintain the immune system. The following nutrients are essential⁵.

  • Vitamins (A, beta-carotene, folic acid, Riboflavin, B6, B12, C, E, D)
  • Minerals (Iron, Zinc, and Selenium), and
  • Dietary lipids.

Probiotic, Prebiotic, Nutrient rich day for a Toddler

  1. Offer plenty of water throughout the day, so fibre rich food can move along well. 
  2. Because toddlers are notorious fussy eaters, it always makes sense to offer several food groups as main meals, so they are successful at feeding themselves. 

Suggested day:

Morning: oats or barley bread toast with nut butter (ex: pistachio), milk. 

Snack: fruit. 

Lunch: chicken drumettes, couscous, with chickpeas and sultanas, with a dash of olive oil, fruit.

Snack: barley flat bread with pea dip and cottage cheese, mandarin.

Dinner: roasted sweetcorn, broccoli, arancinis, grated parmesan, yoghurt, fruit.

Fortified foods and Synbiotics

A varied diet is all that is needed to provide toddlers with everything they need to build and boost their immune system. If your child struggles to eat a good variety of food, they may benefit from:

  • a visit to the doctor to make sure all is well, 
  • a supplementation with vitamin and minerals with over the counter supplements,
  • an offer of fortified breakfast cereals, bread and toddler formula milk drink.
  • pre and probiotics all-in-one supplement (synbiotics).


[i] Mueller NT, Bakacs E, Combellick J, Grigoryan Z, Dominguez-Bello MG. The infant microbiome development: mom matters. Trends Mol Med. 2015 Feb;21(2):109-17. doi: 10.1016/j.molmed.2014.12.002. Epub 2014 Dec 11. PMID: 25578246; PMCID: PMC4464665.

[ii] Yang I, Corwin EJ, Brennan PA, Jordan S, Murphy JR, Dunlop A. The Infant Microbiome: Implications for Infant Health and Neurocognitive Development. Nurs Res. 2016 Jan-Feb;65(1):76-88. doi: 10.1097/NNR.0000000000000133. PMID: 26657483; PMCID: PMC4681407.

[iii] Walsh C, Lane JA, van Sinderen D, Hickey RM. Human milk oligosaccharides: Shaping the infant gut microbiota and supporting health. J Funct Foods. 2020 Sep;72:104074. doi: 10.1016/j.jff.2020.104074. Epub 2020 Jul 3. PMID: 32834834; PMCID: PMC7332462.


[v] Childs CE, Calder PC, Miles EA. Diet and Immune Function. Nutrients. 2019 Aug 16;11(8):1933. doi: 10.3390/nu11081933. PMID: 31426423; PMCID: PMC6723551.

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