Immunity in Infants and Children – basics

The immune system is like the police force of the body, attacking foreign factors that cause health problems, including viruses, bacteria, parasites, and allergens.

It is made up mainly of special types of cells in the blood, called white blood cells, which move around the body and protect vulnerable places, such as the nose, mouth, throat (e.g. tonsils), lungs, gut and broken skin. Further protection from inside the gut is provided by the microbiome.

The immune system starts to switch on from the moment of birth.​ Infants receive factors from mother’s milk that activate and support immune system functions. As children grown, they pick up all kinds of factors from the environment, other kids and adults.

Babies get sick almost three times more frequently than preschoolers ^[1]. This is because the immune system gradually improves its ability to recognize infectious factors over time through exposure, using a process called “natural immunity”, or “acquired immunity”.

The immune system is very complex and includes lots of working processes. This means that virtually all nutrients play some part in it. Some of the ones below are better known for immunity:

• Vitamin A – stimulates white blood cells production and helps prevent damage to walls of the gut, lungs, mouth and skin^[2]
• Omega-3 fats (DHA, EPA): used to make immune system products, protects walls of the gut and skin.
• Zinc – stimulates new white blood cells​, helps wounds to heal
• Iron – used for energy production in the immune system
• Protein – used to make special products in the immune system, such as antibodies​
• Prebiotics – support the microbiome in the gut to block infections​ ^[3]
• Lactoferrin – immune booster from breastmilk, and protects against gut and lung infections ^[4]
• Beta-glucan – stimulates the lung and gut immune system, and protects against colds & flu ^[5]
• Nucleotides – part of breastmilk, and used in the production of new immune system cells

Out of the nutrients listed above, there are some that, if lacking, can increase the risk of kids getting sick. For example, a lack of vitamin A in a child’s diet makes them more likely to get measles ^[6]. Another important one is zinc, where children with lower levels are more susceptible to diarrhea caused by gut infections ^[7]. Diets lacking in omega-3 fats are known to promote the risk of allergies and asthma ^[8].

The problem with undernourishment is most macro- and micronutrients are missing, including the ones above, and this happens over long time periods. Children with this are more likely to suffer from infections ^[9], growth and development delays and prolonged illness. This is why complete nutrition is so important.