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Immune Support: Gut Health and Key Nutrients

Gut Health and the Immune System  

It has been said that immune health starts in the gut; what we eat affects the bacteria (or microbiome) of the digestive tract. A balanced microbiome benefits the immune system in the gut, aiding the intestinal walls (intestinal epithelium) in their job of protecting the body from pathogens.When there is an imbalance of bacteria in the digestive tract, called dysbiosis, we are more susceptible to overgrowth of harmful bacteria and yeast, negatively affecting immune function.2 Factors that could contribute to dysbiosis include diet, constipation, diarrhea, certain medications, and antibiotic use.2 Steps you can take to increase good bacteria in the gut include increasing fiber intake and decreasing the amount of processed sugar you eat. Fiber feeds good bacteria and helps remove toxins from the body while processed foods and sugar feed bad bacteria and yeast.2,3  

Supplementing with a high-quality probiotic can help improve gut health. Lactobacillus and Bifidobacterium have been shown to be especially helpful in aiding the immune response by increasing IgA, IgM, and IgG secreting cells.4,5 Typical starting doses of probiotics are 5 billion colony-forming units (CFUs) for kids and 10 billion CFUs for adults.6  In addition to probiotics and fiber for immune health, increasing protein and omega-3 fatty acid intake can be helpful for immune cell function.7,8  Omega-3 fatty acids like EPA and DHA are especially helpful in autoimmune conditions and have been linked to fewer respiratory tract infections, asthma, and wheezing in children.9  Doses of omega-3 supplements range from 120-1,300 mg daily for kids10,11 and 1,100 mg of DHA/EPA per day for adults.12  Omega-3s are also found in foods including fish, eggs, chia seeds, spinach, and broccoli.  

Key Nutrients for a Healthy Immune System

In addition to eating a variety of whole foods to support beneficial gut bacteria, supplementing with vitamins and herbs can be helpful, especially for those with a compromised immune system.  Vitamins that benefit the immune system include vitamins A, C, and D.  Vitamin A helps maintain mucosal and skin barriers by improving IgA response and also improves natural killer cell activity, an important part of the innate immune system.2,13  Vitamin C is an antioxidant that protects immune cells from oxidative stress2 and has been shown to aid in reducing respiratory infections caused by heavy exercise.14,15,16  Vitamin D plays an important role in the innate response and is especially helpful in those that are deficient (levels <20 ng/mL).17,1  For optimal immune function, vitamin D levels should be between 60-80 ng/mL, and supplementation may be advised for those that spend most of their day indoors. Vitamin D should also be dosed with Vitamin K2. See our previous post to learn more.

As for minerals, zinc is important for healing as it is involved in the formation of DNA and it may also reduce the duration of the common cold.19,20  Furthermore, zinc deficiency can suppress the development of T cells in the thymus causing B cell function to suffer.19 Those with IBS, chronic fatigue syndrome, and HIV as well as those who are obese, anorexic, or elderly are at higher risk of zinc deficiency.19  For additional immune support, colostrum and echinacea are helpful. Colostrum is rich in IgG, enhancing the ability of the white blood cells to kill bacteria while lowering inflammation in the gut.21  Echinacea stimulates activation of macrophages, a type of white blood cell, and natural killer cells in the body.2,22  Research has also shown echinacea may reduce the rate of infections, thus reducing antibiotic use in children.23  Lastly,antiviral supplements such as olive leaf extract24, berberine25, and elderberry26 may reduce sick days and the life cycle of viruses.  A word of caution: those with autoimmune conditions should talk with their provider before starting supplements for immune support to avoid an increase in the body’s autoimmune response. 

Bottom line: Eating a diet rich in whole foods, healthy fats, protein, essential nutrients, and fiber supports the growth of beneficial bacteria in the gut and the proper functioning of white blood cells, keeping our immune system strong. A resilient immune system not only benefits physical health, but increases the quality of time spent with loved ones, so we can be there for every moment- big or small.  You can learn more about functional medicine by joining our next discovery class or book an appointment to work with our team!

SupplementDaily Dose for KidsDaily Dose for Adults
Vitamin A130-6 months: 400 mcg
7-12 months: 500 mcg
1-3 years: 300 mcg
4-8 years: 400 mcg
9-13 years: 600 mcg
14-18 years:
Girls- 700 mcg
Boys- 900 mcg
Women: 700 mcg
Men: 900 mcg
Vitamin C14,27For immune maintenance:
500-1,000 mg
For immune maintenance:
1-2 g
Vitamin D28
*Get levels tested if possible as greater supplementation may be needed if deficient
<1 year: 400-1,000 IU
1-8 years: 600-1,000 IU
9-18 years: 1,500-2,000 IU
1,500-2,000 IU (up to 10,000 IU)
Zinc22,29,307 months-3 years: 3 mg
4-8 years: 5 mg
9-13 years: 8 mg
14-18 years:
Girls- 9 mg
   Boys- 11 mg
Women: 8 mg 
Men: 11 mg 
<2 years old: 3 g
>2 years old: 3 g twice daily
400 mg for influenza
Echinacea332,400 mg (prevention) 
4,000 mg (acute illness)
Doses are for general information only based on the references identified. Consult your healthcare provider to discuss specific doses needed for individuals.

Written by Lizzy Johnston, PharmD Candidate 2021, Cedarville University School of Pharmacy.


  1. Yan F, Polk DB. Probiotics and immune health. Curr Opin Gastroenterol. 2011;27(6):496-501.
  2. Guilliams T.  Strategies for Immune Enhancement.  The Standard.  2008.  Retrieved from  Accessed 13 August 2020.  
  3. Sanchez, A.; Reeser, J.L. et al. Role of sugars in human neutrophilic phagocytosis. Am J Clin Nutr. 1973; 26(11):1180-118
  4. Hatakka K, Savilahti E, Ponka A, Effect of long-term consumption of probiotic milk on infections in children attending day care centres: Double blind, randomized trial. BMJ. 2001:322;1327.
  5. Hojsak I, Snovak N, Abdovic S, Lactobacillus GG in the prevention of gastrointestinal and respiratory tract infections in children who attend day care centers: A randomized, double-blind, placebo-controlled trial. Clin Nutr. 2010;29(3):312-316.
  6. Kligler B, Cohrssen A.  American Family Physician.  2008. Retrieved from
  7. Woodward Bill.  Protein, calories, and immune defenses.  Nutrition Reviews. 2009.
  8. Calder PC. Immunomodulation by omega-3 fatty acids. Prostaglandins Leukot Essent Fatty Acids. 2007;77(5-6):327-335.
  9. Bisgaard H, Sokholm J, Chawes BL, Fish oil-derived fatty acids in pregnancy and wheeze and asthma in offspring. N Eng J Med. 2016;375:2530-2539.
  10. Nagakura T et al. Dietary supplementation with fish oil rich in omega-3 polyunsaturated fatty acids in children with bronchial asthma. Eur Respir J.  2000. 16(5):861-5
  11. Bos D et al.  Reduced Symptoms of Inattention after Dietary Omega-3 Fatty Acid Supplementation in Boys with and without Attention Deficit/Hyperactivity Disorder.  Neuropsychopharmacology.  2015. 40(10):2298-306
  12. National Institutes of Health. Omega 3 Fatty Acids.  Retrieved from  Accessed 19 August 2020.
  13. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002. Available at:
  14. Hemila H, Chalker E. Vitamin C for preventing and treating the common cold. Cochrane Libr. 2013.
  15. Hemila H. Vitamin C and common cold incidence: A review of studies with subjects under heavy physical stress. Int J Sports Med. 1996;17(5):379-383.
  16. Moreira A, Kekkonen RA, Delgado L, Nutritional modulation of exercise-induced immunodepression in athletes: A systematic review and meta-analysis. Eur J Clin Nutr. 2007;61(4):443 460.
  17. Martineau AR, Hanifa Y, Witt KD, Double-blind randomized controlled trial of vitamin D3 supplementation for the prevention of acute respiratory infection in older adults and their carers (ViDiFlu). Thorax. 2015;0:1-8.
  18. Gysin DV, Dao D, Gysin CM, Effect of vitamin D3 supplementation on respiratory tract infections in healthy individuals: A systematic review and meta-analysis of randomized controlled trials. PLoS One. 2016:9
  19. Kurugol Z, Akilli M, Bayram N, Koturoglu G. The prophylactic and therapeutic effectiveness of zinc sulphate on common cold in children. Acta Paediatr. 2006;95(10):1175-1181.
  20. Allan GM, Arroll B. Prevention and treatment of the common cold: Making sense of the evidence. CMAJ. 2014:186(3):190-199.
  21. Ulfman L, Leusen J, Savelkoul H, et al. Effects of Bovine Immunoglobulins on Immune Function, Allergy, and Infection.  Front Nutr. 2018. doi: 10.3389/fnut.2018.00052
  22. Gan, X.H.; Zhang, L. et al. Mechanism of activation of human peripheral blood NK cells at the single cell level by Echinacea water soluble extracts: recruitment of lymphocyte-target conjugates and killer cells and activation of programming for lysis. Int Immunopharmacol. 2003; 3(6):811-824
  23. Cohen, H.A.; Varsano, I. et al. Effectiveness of an Herbal Preparation Containing Echinacea, Propolis, and Vitamin C in Preventing Respiratory Tract Infections in Children: A Randomized, Double-blind, Placebo-Controlled, Multicenter Study. Arch Pediatr Adolesc Med. 2004. doi:10.1001/archpedi.158.3.217
  24. Somerville V, Moore R, Braakhuis A. The Effect of Olive Leaf Extract on Upper Respiratory Illness in High School Athletes: A Randomised Control Trial.  Nutrients. 2019. 11(2):358. doi: 10.3390/nu11020358
  25. Warowicka A, Nawrot R, Gozdzicka-Jozefiak A.  Antiviral activity of berberine.  Arch Virol.  2020.  165(9):1935-1945.  doi: 10.1007/s00705-020-04706-3
  26. Zakay-Rones Z, Thom E, Wollan T, Wadstein J. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J Int. Med Res.  2004.  32(2):132-40.  doi: 10.1177/147323000403200205
  27. Hemila H. Vitamin C supplementation and common cold symptoms: Factors affecting the magnitude of the benefit. Med Hypotheses. 1999;52(2):171-178.
  28. Holick M.  Vitamin D: A D-lightful solution for health.  J Investig Med.  2013.  doi: 10.231/JIM.0b013e318214ea2d
  29. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002. Available at:
  30. National Institutes of Health. Zinc, Fact Sheet for Health Professionals. Accessed 19 August 2020
  31. Cesarone MR, Belcaro G, Di Renzo A, Dugall M, et al. Prevention of influenza episodes with colostrum compared with vaccination in healthy and high-risk cardiovascular subjects: the epidemiologic study in San Valentino.  Clin Appl Thromb Hemost. 2007.  Doi: 10.1177/1076029606295957
  32. Saad K, Abo-Elela MG, El-Baseer KA, et al. Effects of bovine colostrum on recurrent respiratory tract infections and diarrhea in children.  Medicine (Baltimore) 2016;95(37):e4560.
  33. Jawad M, Schoop R, Suter A, et al. Safety and efficacy profile of Echinacea purpurea to prevent common cold episodes: A randomized, double-blind, placebo-controlled trial. Evid Based Complement Alternat Med 2012;2012:841315. Epub 2012 Sep 16. 
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