Colds, infections, and injuries. These are all part of the childhood experience. As parents, we want our kids to be as healthy as they can be, and if they become sick or hurt, we want them to recover as soon as possible. The key to this is having a robust immune system. Good immunity helps prevent illness and boosts recovery time. If you’re in the midst of winter, or cruising through the summer, any time of year is the best time of year to optimize immune health.
What is Immunity?
Immunity is the body’s ability to fight off infections and viruses, and help children (and ourselves) bounce back from an injury or illness. The immune system includes many cells and organs that work together to build this defense. We are born with innate immunity, like our skin which provides a protective barrier against bacteria. We accumulate adaptive immunity, which develops when we are exposed to disease or get vaccinated to ward off disease. We also have passive immunity which is “borrowed” and short-lived, like the immunity conveyed from a mother to an infant who is breastfeeding.
A strong immune system depends on, in part, nutrition. We often think about vitamin C when it comes to our immune system, but there are other nutrients that play a role in keeping our immunity hearty and healthy.
Nutrients Involved with Immunity
There’s a long list of nutrients involved in immunity, including protein, vitamins A, D, C, E, vitamin B6 (pyridoxine) and B12 (cobalamin), folate, iron, selenium, copper, and zinc. These nutrients, the immune system, and infection work harmoniously together. When one of these are out of balance, such as with a nutrient deficiency, a lowered immune response and a higher risk for infection may occur. ¹ The good news is that correcting a nutrient deficiency can improve immune health, resistance to infection, and help your child bounce back, faster. ²
Some of these nutrients focus on maintaining our innate immunity so bacteria or other invaders can’t get in and harm the body. Other nutrients are involved in creating and maintaining the immune cells, the warriors that battle against bacterial invaders. Some nutrients have the job of restricting the growth of bacteria – they have anti-microbial properties, killing bacteria that’s gained entry into the body. And when our body becomes ill or infected, other nutrients support the inflammatory response. Last, many nutrients help us make antibodies.
| Function | Nutrients |
|---|---|
| Maintain the integrity of barriers (skin, mucus membranes in the digestive tract and respiratory tract) | Vitamins A, D, C, E, B6, B12, and folate; and iron and zinc |
| Create and maintain immune cells | Vitamins A, D, C, E, B6, B12, and folate; zinc, iron, copper, selenium, and magnesium |
| Anti-microbial effects | Vitamins A, D, and C; zinc, iron, copper, and selenium |
| Support inflammatory response | Vitamins A, D, C, E, and B6; zinc, copper, iron, selenium, and magnesium |
| Make antibodies | Vitamins A, D, C, E, B6, B12, and folate; zinc, selenium, and magnesium |
*Adapted from (Maggini et al., 2018)
The immune system is complex! It’s easy to see that nutrition helps children stay healthy, especially when they’re growing.
A Spotlight on Vitamin D and Immunity
Vitamin D is a nutrient I consider essential to health. For one, there is a cell receptor for vitamin D in every cell of the body. ³ To me, that means it’s critical for normal body functioning. And yet, the tricky thing about vitamin D is that it’s not necessarily easy to get enough of it. There are limited food sources of vitamin D. And, we lather our kids (or ourselves) with sunscreen, limiting the activation of vitamin D in the skin.
When it comes to immunity, Vitamin D acts as an anti-inflammatory substance, and boosts the production of immune cells. ⁴ Studies show a link between low vitamin D status and more immune-based conditions such as psoriasis, arthritis, and type 1 diabetes. Vitamin D deficiency is also associated with autoimmune diseases and infections. For optimal immune function, studies suggest we maintain a vitamin D level of at least 30 ng/mL. ⁴
For babies who are breastfed, a vitamin D supplement is needed (talk with your doctor). If your family lives in the northern hemisphere of the U.S., has dark-pigmented skin, or regularly uses sunscreen or protective layering, your vitamin D status may be inadequate. Check with your healthcare provider about vitamin D testing, supplementation, and choose foods with vitamin D like D-fortified milk, fortified breakfast cereal, fatty fish, mushrooms exposed to light, and D-fortified eggs and orange juice.
Dairy Foods Can Support Your Child’s Immunity
The good news is that many foods offer the nutrients known to support immunity. From vegetables and fruit, to eggs, fish and meat, a well-balanced, nutritious diet is one of your best defenses against infection and illness. Milk and dairy foods happen to contain six of the key immune-supporting nutrients: protein, vitamin A, D, and B12, zinc, and selenium. Who knew milk and dairy foods had so many nutrients to support immunity?
But, sadly, many children have poor diet quality. When measured against a perfectly nutritious diet (a Healthy Eating Index (HEI) score of 100), toddlers score a concerning 61 and 5-to-8-year-olds score a 55. It goes downhill from there with pre-teens and teens scoring 52 and 51, respectively. One way to easily improve your child’s diet quality and support their immune system is to offer 3 servings of dairy each day.
Jill Castle is the author of the forthcoming book, Kids Thrive at Every Size (Workman 2024) and one of the nation’s premier childhood nutrition experts. She is the founder and CEO of The Nourished Child®, a nutrition education website and podcast for parents, and the author of books including Eat Like a Champion, Try New Food, The Smart Mom’s Guide to Starting Solids, The Smart Mom’s Guide to Healthy Snacking, and co-author of Fearless Feeding.
References:
- Maggini, S., Pierre, A., & Calder, P. C. (2018). Immune Function and Micronutrient Requirements Change over the Life Course. Nutrients, 10(10), 1531. https://doi.org/10.3390/nu10101531
- Gombart, A. F., Pierre, A., & Maggini, S. (2020). A Review of Micronutrients and the Immune System–Working in Harmony to Reduce the Risk of Infection. Nutrients, 12(1), 236. https://doi.org/10.3390/nu12010236
- Bikle, D. D. (2016). Extraskeletal actions of vitamin D. Annals of the New York Academy of Sciences, 1376(1), 29–52. https://doi.org/10.1111/nyas.13219
- Charoenngam, N., & Holick, M. F. (2020). Immunologic Effects of Vitamin D on Human Health and Disease. Nutrients, 12(7), 2097. https://doi.org/10.3390/nu12072097
