Vitamins and minerals are necessary for the proper functioning of the human body. In the 1700s, James Lind proved that scurvy was curable by consuming citrus fruits while crews were out to sea for prolonged periods of time. Over thousands of years, humans struggled to gain access to a consistent and quality food source that could cover the basics of macro- and micronutrient needs. The advent of animal husbandry and communal farming changed this problem forever. However, the world continues to change, and in recent years the developed nations of the world have the opposite problem: caloric excess.

Unfortunately, this caloric change in quantity was not accompanied by quality with respect to the micronutrients in the diet, children included. Thus, many children face problems when it comes to immune health and current dietary trends. The modern diet is often lacking in the critical nutrients necessary for adequate cellular function. A few micronutrients in particular were often found in low serum volumes in a clinic evaluation and during study.₁

One of the most important micronutrients for immune health is vitamin D. It is known as the sun hormone due its ability to be synthesized by the skin via direct sun exposure. It is also found in specific foods including mushrooms, dairy products, small oily fish, eggs, and liver. A lack of vitamin D leads to critical defects in immune tolerance, particularly the ability of T regulator cells to downregulate inflammation and avoid auto-reactivity. Vitamin D affects B and T cell activity in innate and adaptive immune responses for pathogen presentation as well as inflammatory dampening post infection.₂ The end result of low circulating vitamin D levels is a functional inability to adequately present pathogens for recognition and killing leading to a delayed response and potential worsened infectious outcome coupled to a dysfunctional inflammation resolution phase leading to autoreactivity and allergy.₃ Depending on genetic skin pigmentation, 30 minutes of daily sun exposure coupled to the adequate nutritional intake of oily fish, eggs, and mushrooms is a recipe for immune health in a child.

Zinc is a very important mineral found in many plant and animal food sources including meat, eggs, shellfish, legumes, and whole grains. Zinc is a key cofactor component of many cellular interactions including immune cell proliferation and activity of both the innate and adaptive cell lines. Zinc inadequacy leads to alterations in immune cell signaling, lymphocyte production, and phagocytosis.₄ These changes make the function of innate immunity, the critical aspect of human child health, weakened to the point of recurrent pathogen susceptibility. Clinical experience notes improvement in infectious disease stamina in children supplemented with zinc._5,6 Mechanistically and via study, there is clear evidence for the recommendation to encourage children to consume sources of zinc such as high quality meat, eggs, shellfish, legumes, and whole grains to maintain immune health.

Vitamin C is found in citrus fruits, peppers, tomatoes, brassica vegetables, and potatoes. Mechanistically, vitamin C is critical to a child’s immune health.₇ Vitamin C has the role of stimulating the production and function of neutrophils, lymphocytes, and phagocytes, providing the critical first line of defense against a pathogen innately. The antioxidant effects of vitamin C protect the white blood cells from damage after they destroy pathogens with oxygen radicals.₈ The key piece of the vitamin C story is that preferably, children should consume this vitamin via whole food sources and not as sugar-packed juices that compromise immune function through hyperglycemia. The whole food first mentality is key for children’s immune health.

Lastly, vitamin A, like vitamin D, has a critical role; a lack of vitamin A leads to critical defects in immune tolerance, the ability of T regulator cells to downregulate inflammation and avoid auto-reactivity. Preformed vitamin A (retinol) is found in animal products, while fruit and vegetables contain the precursor of vitamin A known as carotenoids. The specific food sources are bright yellow, red, and orange fruits and vegetables, greens like spinach, as well as oily fish like salmon, liver, and dairy products. Vitamin A is responsible for T cell homing and differentiation with a bias towards tolerance and calming of inflammation.₉ Focusing a child’s diet on the consumption of varied and brightly colored vegetables and fruits will go a long way toward a vitamin A sufficiency state and healthy immune system.