Back-to-School - How to Boost the Health of Your Child’s Immune System (And Yours!)

Going back to school coincides with the start of the cold and flu season, so this is the ideal time to think about the health of your child’s immune system.

The common cold is the most frequent illness. Adults typically experience 1–3 colds per year, whereas children have an average of FIVE but could have up to ELEVEN (!!) colds annually.^1,2

More than 200 viruses are known to cause symptoms of the common cold, so supporting immune function could be a good strategy to reduce the severity, duration, and possibly the number of colds this year since it is impossible to avoid all those viruses!

This blog post will explore the latest research that shows natural options could benefit optimal immune function. Continue reading to learn more!

Nutrition and the Common Cold

Symptoms of the common cold can include nasal congestion, sneezing, facial pressure, loss of taste, loss of smell, runny nose, sore throat, cough, headache, muscle aches, pain, discomfort, and fever. The common cold usually lasts less than ten days but can significantly disrupt life for your child and you.³

Micronutrients, including iron, zinc, selenium, copper, chromium, and vitamins A, C, D, & E, are essential for the optimal function of your child’s immune system. No single food contains all the nutrients required for immune function, but consuming a balanced whole-food diet daily in conjunction with a healthy appetite and optimal digestion can provide the necessary components involved in the immune response.⁴

To date, clinical trials studying the effects of nutrients on immune function and specific illnesses mostly include adults. Some clinical trials have included children, and the available evidence is reviewed below.

Could a Vitamin C Supplement Boost Your Child’s Immunity?

Dozens of studies note that vitamin C naturally and beneficially impacts the ability of white blood cells to respond to an infection, boosts antibody production, affects the replication of viruses, and supports the production of interferon, all of which could reduce the burden of a viral infection. Research also shows vitamin C is a highly efficient and water‐soluble antioxidant that protects against the oxidative stress produced during an infection. White blood cells even have a specialized transport system that regenerates vitamin C to enhance the antioxidant benefits. A vitamin C deficiency impairs immune function.^5,6

According to research, vitamin C supplementation could be more beneficial for children this time of year than adults. A Cochrane review published in 2013 suggests regular vitamin C supplementation reduces the duration and severity of the common cold in children. The data show supplementation with 200 mg of vitamin C daily minimizes the duration and severity of upper respiratory tract infections, including the common cold, by 14-18% in children.⁵

Divided doses of 1 to 2 grams of vitamin C per day in children shortened the duration of a cold by 18%. Some studies suggest regular vitamin C supplementation could reduce the duration of colds by up to 21% in children.⁵

The research does not yet suggest vitamin C can reduce the number of colds experienced by children each year. Also, therapeutic trials of vitamin C supplementation during a viral infection does not show it is beneficial against the common cold, but high-quality therapeutic trials had not yet been performed with children at the time of the Cochrane analysis in 2013.⁵

Two placebo-controlled therapeutic trials assessing the efficacy of probiotics plus 50 mg of vitamin C in children were published in 2015 and 2021 and known as the PROCHILD and PROCHILD-2 studies. The two studies determined the therapeutic combination of probiotics and vitamin C reduced both the incidence and duration of upper respiratory tract infections in children.^7-9

Furthermore, the significant reduction in the incidence and duration of symptoms in preschool children receiving the therapeutic probiotic and vitamin C combination was associated with fewer visits to the doctor, plus a 47% reduction in prescriptions for antibiotics.⁹

More research is needed, but, in age-appropriate and regular doses, vitamin C tends to be a safe and affordable option to potentially reduce the severity and duration of the common cold.⁵

The Best Natural Probiotics for Your Kid’s Immunity

As noted in the section above, data from the PROCHILD and PROCHILD-2 studies show combining probiotics with vitamin C significantly reduces the duration and incidence of respiratory infections, including the common cold.⁹

Research also suggests infants and children with a respiratory tract infection who supplement with probiotics alone decrease their risk of being prescribed antibiotics by 41-42% compared to placebo.^9,10 Reducing the number of antibiotics taken during childhood may reduce the risk of side effects and long-term damage to the gut microbiome.¹¹

The specific strains of probiotics used in the PROCHILD and PROCHILD-2 studies include Lactobacillus acidophilus CUL21, Lactobacillus acidophilus CUL60, Bifidobacterium bifidum CUL20, and Bifidobacterium animalis subsp. lactis CUL34.⁹

Other probiotic strains administered to children in clinical trials showing immune benefits include:

• Lacticaseibacillus rhamnosus GG (LGG)
• Lacticaseibacillus paracasei subsp. paracasei DN-114 001/CNCM I-1518
• Bifidobacterium longum BB536
• Lactobacillus plantarum HEAL9
• Lactobacillus paracasei (8700:2 or N1115)^9,10

Most of the beneficial studies administered 10⁹ or 10¹¹ total colony‐forming units (CFU) of one or two probiotic strains each day for more than three months.¹⁰

Vitamin A Gets an A+ for Immune Support!

Vitamin A is a fat-soluble vitamin required for optimal growth & development, cellular communication, immune function, and skin health.^12,13 Vitamin A is also crucial for vision since it is a component of the protein that responds to light entering the eye.¹²

Vitamin A is available via diet and supplements as preformed vitamin A and provitamin A carotenoids. Good sources of preformed vitamin A include dairy products, eggs, fish, and organ meats (liver). Good sources of provitamin A carotenoids include colorful plant foods, such as sweet potatoes, pumpkin, spinach, and carrots.¹²

Regarding immune function, vitamin A offers antioxidant benefits, immunomodulating effects, antiviral activity, enhanced natural barriers (skin), and improved cell signaling.³ Vitamin A also beneficially affects natural killer (NK), T-reg, and T-helper cell activity, the differentiation of immune cells, antibody production, and the phagocytosis of macrophages.¹⁴

Recent surveys of children in China showed low blood levels of vitamin A were associated with a high incidence of recurrent respiratory tract infections (RRTIs). Moreover, researchers determined a low blood vitamin A concentration during an active respiratory tract infection was associated with the development of recurrent infections. Also, a low intake of foods rich in vitamin A was associated with RRTIs in the children.^15,16

Despite the known effects of vitamin A on immune function and the association between suboptimal vitamin A status and respiratory infections, clinical studies assessing the beneficial effects of vitamin A supplementation on colds and the flu have had mixed results. Some studies show no benefit, while others suggest vitamin A supplementation for immune support is protective.^17,18 A study by Zhang, et al. even suggests excessive vitamin A supplementation could increase respiratory infections.¹⁹

The differing results of the studies might depend on how much vitamin A the participants were already consuming in their diet. Thus, it is likely best to ensure your child is getting the Recommended Daily Allowance (RDA) for vitamin A from their diet and consider supplementation to prevent deficiency or insufficiency if needed.¹⁷

The RDA for vitamin A varies based on age. The RDA for 4 - 8-year-old children is 400 mcg RAE (retinol activity equivalents). The RDA for 9 - 13-year-old children is 600 mcg RAE. The RDA for 14 - 18-year-old males is 900 mcg RAE. The RDA for 14 - 18-year-old females is 700 mcg RAE unless they are pregnant or breastfeeding, which increases their needs to 750 mcg RAE or 1,200 mcg RAE, respectively.¹²

High doses of preformed vitamin A can cause birth defects, so it should never be consumed in large quantities during or just before pregnancy. In adults and college-age students, The RDA for males is 900 mcg RAE, and 700 mcg RAE for females who are neither pregnant nor breastfeeding.¹²

Please note it is possible to consume too much of the preformed vitamin A. Consuming too much preformed vitamin A at any age can cause vitamin A toxicity, so always ensure dietary intake and supplemental doses of vitamin A are appropriate for age and health status with a pediatrician or doctor.^12,20

Vitamin D for Back-to-School Immunity During the Cold & Flu Season

One of the most important benefits of adequate vitamin D is the optimal regulation of the immune system. Vitamin D deficiency is associated with increased susceptibility to infections and an impaired immune response.^3,19 Research also shows vitamin D deficiency is a risk factor for recurrent respiratory tract infections (RRTIs) in children.^16,20,21

Among its many actions in the body, vitamin D enhances the body’s immune response by promoting the synthesis of peptides with powerful antimicrobial activity, including cathelicidin and LL37 protein. Vitamin D also directly impacts the:

• Signaling mechanisms downstream of the T-cell-receptor (TCR) of T cells
• Promotion of Treg responses (T cells, including Treg cells, are immune cells)
• Maturation of dendritic cells
• Expression of Nrf2
• Enhancement of epithelial barrier function in both the skin and the lungs
• Maturation of type II pneumocytes in the lungs
• Promotion of surfactant production in the lungs
• Control of calcium-mediated and redox signaling
• Modulation of cytokine secretion
• Recruitment of eosinophils (a type of white blood cell) in the airways^20,22

Moreover, research shows children with recurrent diseases of the airways often have sub-optimal levels of both vitamin D and vitamin A, and nutrient replenishment results in decreased numbers of infections and an overall improvement of health. Vitamin D supplementation during a respiratory infection can significantly reduce the duration and severity of the infection while improving the quality of life in those with low levels.^3,20

Several studies demonstrate that vitamin D supplementation improves lung function in children with bronchiolitis and reduces the likelihood of developing respiratory infections in general. Bronchiolitis can be caused by the same viruses that cause the common cold, including RSV, rhinovirus, and coronavirus.^20,23

Please note it is possible to take too much vitamin D, so be mindful of the Adequate Intake (AI) and Recommended Daily Allowance (RDA) for each age group. The current AI for ages 0-12 months is 10 mcg (400 IU) per day, and the RDA for ages 1 - 70 years is 15 mcg (600 IU) daily. Vitamin D can also be produced in the body during sun exposure.²⁴

Micronutrients are essential for the proper function of your child’s immune system. Overall, they regulate innate and adaptive immunity, antibody production, cytokine activity, and the immune response of immune cells, such as Th1 and Th2 lymphocytes.⁴ 

Supplementation with the vitamins mentioned above and probiotics could be a safe and low-cost option to support the optimal function of the immune system in children. Supplementation should only be considered in addition to a healthy diet, and dosages must be within the recommended upper safety limits set by experts.²¹

Children also need to get adequate sleep, manage stress, stay physically active, and take precautions, such as washing their hands, to remain as healthy as possible throughout the cold and flu season.²⁵

InterPlexus Supplements that Support Optimal Immunity While on Campus During the Cold & Flu Season*

Flavo PlexC is a potent blend of vitamin C and organic plant extracts that supports optimal adrenal function and a healthy immune response while on campus during the cold and flu season.*

Zinc Plus is a unique supplement that offers highly bioavailable vitamin C and zinc to support a healthy immune system and boost immunity when going back to school.*

Fortéfy is a probiotic supplement that contains the best high-quality, dairy-free strains of probiotic organisms to support optimal immune function in students during the cold and flu season.*

Always consult with a healthcare professional before beginning a new supplement routine, especially if you take medications or have underlying health conditions.

References:

1. Passioti M, Maggina P, Megremis S, et al. The common cold: potential for future prevention or cure. Curr Allergy Asthma Rep. 2014;14(2):413. doi:10.1007/s11882-013-0413-5
2. Somerville VS, Braakhuis AJ, Hopkins WG. Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis. Adv Nutr. 2016;7(3):488-497. doi:10.3945/an.115.010538
3. Ciprandi G, Tosca MA. Non-pharmacological remedies for the common cold. Minerva Pediatr (Torino). 2023;75(1):75-86. doi:10.23736/S2724-5276.21.06312-6
4. D'Auria E, Calcaterra V, Verduci E, et al. Immunonutrition and SARS-CoV-2 Infection in Children with Obesity. Nutrients. 2022;14(9):1701. doi:10.3390/nu14091701
5. Hemilä H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2013;2013(1):CD000980. doi:10.1002/14651858.CD000980.pub4
6. Berger MM, Herter-Aeberli I, Zimmermann MB, et al. Strengthening the immunity of the Swiss population with micronutrients: A narrative review and call for action. Clin Nutr ESPEN. 2021;43:39-48. doi:10.1016/j.clnesp.2021.03.012
7. Garaiova I, Muchová J, Nagyová Z, et al. Probiotics and vitamin C for the prevention of respiratory tract infections in children attending preschool: a randomised controlled pilot study. Eur J Clin Nutr. 2015;69(3):373-379. doi:10.1038/ejcn.2014.174
8. Garaiova I, Paduchová Z, Nagyová Z, et al. Probiotics with vitamin C for the prevention of upper respiratory tract symptoms in children aged 3-10 years: randomised controlled trial. Benef Microbes. 2021;12(5):431-440. doi:10.3920/BM2020.0185
9. Paduchová Z, Nagyová Z, Wang D, Muchová J. The impact of probiotics and vitamin C on the prevention of upper respiratory tract symptoms in two preschool children cohorts. Nutr Res Pract. 2024;18(1):98-109. doi:10.4162/nrp.2024.18.1.98
10. Zhao Y, Dong BR, Hao Q. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev. 2022;8(8):CD006895. doi:10.1002/14651858.CD006895.pub4
11. McDonnell L, Gilkes A, Ashworth M, et al. Association between antibiotics and gut microbiome dysbiosis in children: systematic review and meta-analysis. Gut Microbes. 2021;13(1):1-18. doi:10.1080/19490976.2020.1870402
12. Office of dietary supplements - vitamin A and carotenoids. NIH Office of Dietary Supplements. December 15, 2023. Accessed July 5, 2024. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
13. Chen G, Weiskirchen S, Weiskirchen R. Vitamin A: too good to be bad?. Front Pharmacol. 2023;14:1186336. doi:10.3389/fphar.2023.1186336
14. Spinas E, Saggini A, Kritas SK, et al. Can vitamin a mediate immunity and inflammation?. J Biol Regul Homeost Agents. 2015;29(1):1-6.
15. Zhang X, Dai X, Li X, et al. Recurrent respiratory tract infections in children might be associated with vitamin A status: a case-control study. Front Pediatr. 2024;11:1165037. doi:10.3389/fped.2023.1165037
16. Sun M, Yan Z, Sun R, et al. Dynamic monitoring and a clinical correlation analysis of the serum vitamin A, D, and E levels in children with recurrent respiratory tract infections. Am J Transl Res. 2022;14(5):3533-3538.
17. Timoneda J, Rodríguez-Fernández L, Zaragozá R, et al. Vitamin A Deficiency and the Lung. Nutrients. 2018;10(9):1132. doi:10.3390/nu10091132
18. Abdelkader A, Wahba AA, El-Tonsy M, et al. Recurrent respiratory infections and vitamin A levels: a link? It is cross-sectional. Medicine (Baltimore). 2022;101(33):e30108. doi:10.1097/MD.0000000000030108
19. Zhang Y, Lu Y, Wang S, et al. Excessive Vitamin A Supplementation Increased the Incidence of Acute Respiratory Tract Infections: A Systematic Review and Meta-Analysis. Nutrients. 2021;13(12):4251. doi:10.3390/nu13124251
20. Parisi GF, Carota G, Castruccio Castracani C, et al. Nutraceuticals in the Prevention of Viral Infections, including COVID-19, among the Pediatric Population: A Review of the Literature. Int J Mol Sci. 2021;22(5):2465. doi:10.3390/ijms22052465
21. Pecora F, Persico F, Argentiero A, et al. The Role of Micronutrients in Support of the Immune Response against Viral Infections. Nutrients. 2020;12(10):3198. doi:10.3390/nu12103198
22. Costagliola G, Nuzzi G, Spada E, et al. Nutraceuticals in Viral Infections: An Overview of the Immunomodulating Properties. Nutrients. 2021;13(7):2410. doi:10.3390/nu13072410
23. Justice NA, Le JK. Bronchiolitis. In: StatPearls. Treasure Island (FL): StatPearls Publishing; June 26, 2023.
24. Office of dietary supplements - vitamin D. NIH Office of Dietary Supplements. July 26, 2024. Accessed July 29, 2024. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/.
25. McCarthy C. Boosting your child’s immune system. Harvard Health. July 17, 2023. Accessed July 30, 2024. https://www.health.harvard.edu/blog/boosting-your-childs-immune-system-202110122614.