The Development of a Child’s Immune System

When a baby is born its immune system is immature. The mother’s antibodies are shared with the baby in the last trimester of pregnancy, which helps to protect the baby in those first few weeks. However, these antibodies do not last and will disappear after the first few months.¹

During infancy, your child’s immune system is immature because it is yet to encounter many germs. During this time young children are particularly susceptible to respiratory tract and gastrointestinal infections.¹ As they are exposed to different bugs over time, their adaptive immunity develops, and they’ll gradually build up immunity and get fewer infections.¹ By the early teenage years, the immune system is almost fully developed.¹

Preschool-Aged Children and Infections

The average preschool child has 6-8 colds per year, and often more for children attending childcare facilities.² It's also very common for kids to get secondary ear infections after a respiratory tract infection.² Other common childhood illnesses include gastroenteritis, hand, foot, and mouth disease, whooping cough, respiratory syncytial virus (RSV), conjunctivitis, and molluscum contagiosum virus.² Just to name a few! 

It can be rough on the child and the parents or caregiver as it might feel like your child is sick for weeks at a time, barely getting over one illness before getting another one. Not to mention sharing it with siblings and other family members. Supporting your child’s immune system may help them to fight off these infections. 

Tips for Building a Healthy Immune System

Ensure a varied and balanced whole food diet

When it comes to food choices and nutrition, especially for your child, its easy get caught up in specifics, trying to pick the ideal healthy option. Rather than getting caught up in the specifics of it all, aim for a diet that is full of fresh and unprocessed foods from all the food groups.

The more variety you offer the better, even if they only have small amounts. Exposure is key to getting them to broaden their palate and ensure they are obtaining a broad range of nutrients needed for growth, development, and immune function. And remember building new eating habits can take time, so try to be patient.

Top Tips:

• Offer a rainbow of different vegetables and fruits.
• Focus on quality meats and seafood, such as chicken, beef, lamb, and salmon.
• Opt for sugar free dairy sources, such as yoghurts and milk.
• Offer a variety of wholegrains, including quinoa, brown rice, rye, spelt and oats.
• Get them involved. It doesn’t have to be every meal, but they will be more likely to try something new if they’ve helped prepare it.

Outdoor play time

Playing outside can help build a child’s immune system, especially messy play in the dirt. Playing outside helps to expose your child’s skin to good bacteria and helps to strengthen their immunity.³ It also exposes them to healthy levels of vitamin D, which further supports immune development and function.⁸

Practice good hand washing hygiene

Young children frequently touch their eyes, nose, and mouth without washing their hands. This is the most common way germs are spread.⁴ Good hand hygiene can help to reduce infection incidence and symptoms.⁴ Get them involved from a young age and make it fun, see how many bubbles they can make on their hands with the soap.

Specific Nutrients for Immune Health

While good nutrition generally is necessary for immune function, there are some nutrients of particular importance. Keep in mind that if your child has a balanced diet, they will likely be meeting their nutritional needs.

Zinc

Children have a higher demand for zinc compared to adults, especially during growth spurts.⁵ Zinc helps to support growth and development, immune function and response, gut health, mood, and behaviour.⁵

Iron

Iron is highly important in the early years, it is involved with brain development, tissue growth and is required for optimal immune responses and function.⁶ Low iron stores impact white blood cells in the innate immune system, which is the first line of defence against an invading viral or bacterial pathogen.⁷

Vitamin D

Vitamin D helps to regulate the immune system and immune responses to an infection.⁸ Research has also highlighted that vitamin D supplementation can reduce the rate of infections in children.⁸

Omega 3 fatty acids

Omega 3 fatty acids are utilised in children to help with brain development and growth, regulation of the nervous system and with immune development.⁹ Optimal consumption of omega-3 fatty acids helps to activate immune cells and the immune systems response to an infection.¹⁰

Probiotics

An optimal balance between the good and bad bacteria within our children’s gut allows for a greater ability to digest foods and absorption of nutrients which helps support immune function.¹¹ Maintaining a healthy balance of bacteria in the digestive tract with probiotics has been shown to help immune response to infections especially upper respiratory tract infections and healthy immune function.¹²

Speak to your healthcare practitioner for more information on foods that are rich in these nutrients, and whether immune-supportive supplements are suitable for your child.

References

1. Simon AK, Hollander GA, McMichael A. Evolution of the immune system in humans from infancy to old age. Proceedings of the Royal Society B: Biological Sciences. 2015 Dec 22;282(1821):20143085.
2. Collins JP, Shane AL. Infections associated with group childcare. Principles and practice of pediatric infectious diseases. 2018:25.
3. Sembiring TB, Maruf IR, Susilo CB, Hidayatulloh AN, Bangkara BM. Health literacy study on approaching forest and boosting immune system strategy. International Journal of Health Sciences. 2022;6(1):40-9.
4. Willmott M, Nicholson A, Busse H, MacArthur GJ, Brookes S, Campbell R. Effectiveness of hand hygiene interventions in reducing illness absence among children in educational settings: a systematic review and meta-analysis. Archives of disease in childhood. 2016 Jan 1;101(1):42-50.
5. Maggini S, Wenzlaff S, Hornig D. Essential role of vitamin C and zinc in child immunity and health. Journal of International Medical Research. 2010 Apr;38(2):386-414..
6. Armitage AE, Moretti D. The importance of iron status for young children in low-and middle-income countries: a narrative review. Pharmaceuticals. 2019 Apr 16;12(2):59.
7. Hassan TH, Badr MA, Karam NA, Zkaria M, El Saadany HF, Rahman DM, Shahbah DA, Al Morshedy SM, Fathy M, Esh AM, Selim AM. Impact of iron deficiency anemia on the function of the immune system in children. Medicine. 2016 Nov 1;95(47):e5395.
8. Mailhot G, White JH. Vitamin D and immunity in infants and children. Nutrients. 2020 Apr 27;12(5):1233.
9. DiNicolantonio JJ, O’Keefe JH. The importance of marine omega-3s for brain development and the prevention and treatment of behavior, mood, and other brain disorders. Nutrients. 2020 Aug 4;12(8):2333.
10. Gutiérrez S, Svahn SL, Johansson ME. Effects of omega-3 fatty acids on immune cells. International journal of molecular sciences. 2019 Oct 11;20(20):5028.
11. Ouwehand AC. Antiallergic effects of probiotics. The Journal of nutrition. 2007 Mar 1;137(3):794S-7S.
12. Saavedra JM. Use of probiotics in pediatrics: rationale, mechanisms of action, and practical aspects. Nutrition in clinical practice. 2007 Jun;22(3):351-65.