Children have about five to seven colds per year. A big part of the reason is because they spend time at school or in day-care centers where they're in close contact with other kids most of the day. Also, kids aren't as conscientious about sneezing into the crook of their arm or frequent hand washing -- not to mention keeping their hands to themselves. And to top it off, their young immune systems aren't yet strong enough to fight off colds. -WebMD
Food and for that matter nutritious food will only give your kids ingredients but there immunity won't come this way. if you need your kids to be strong with better immunity, put them into exercise and give a little less of food.
Over nutrition is the worse thing you can do to your kids.
Over nutrition decreases body immunity with increase in fat accumulation in various body parts. So obesity resulting from over nourishment is never helpful as it directly and indirectly reduces immunity. There are some references as:
Chapter Pathogenesis of NASH: How Metabolic Complications of Overnut...
Article Changes in Nutritional Status Impact Immune Cell Metabolism ...
Article The human gut microbiota: Metabolism and perspective in obesity
I hope these references indirectly proves my viewpoint.
Because the innate immunity , and the immune system is not fully developed and the nature of food if it is unhealthy or excess of the required size, it leads to the appearance of diseases .
Children are a complicated set of human beings and everything about them could be a problem. Nutrition alone can be a problem in terms of quality and quantity, when and how. We know in part and discuss, manage and prevent also in part. Not all sicknesses are towards death. Most of the time they are temporary discomforts for cell and/or tissue regeneration, immune system adjustments, proper physiological and emotional developments as well as psychological advancement.
Since children have a less developed immune system, therefore, they become sick despite of healthy nutrition. In addition to this, lack of hygiene is the another reason for sickness of children.
With healthy nutrition, we can give childrens immune systems a better chance at preventing some illnesses before they strike Even though we can’t control which viruses or bacteria latch onto our bodies. In addition, the immune system of children is not sufficiently developed to fight certain infections.
Because they do not follow a balanced health system that contains minerals, vitamins and fiber. Children need a healthy diet because they are in the process of building their bodies and need large amounts of energy so it is the duty of the parents to return their children to food containing minerals, vitamins and fibers that are found in eggs, milk and meat.
Immunity in children are exposed to different environments and by this way they learnt to fight against them slowly. Once they reach puberty, their immune system get fully developed.