Immunity Series Part 2: A Supplement Approach


As a Naturopathic doctor, I am commonly using many supplements and nutritional interventions for immune health. It is now common knowledge that Vitamin C can help with colds, and that we need more Vitamin D in the winter for mood, immune health and general disease prevention. What is less known are the effects of other supplements such as probiotics regarding immune health, and are these supplements better for cold and flu prevention (maintenance of a good immune system) or treatment? Read on below for what I have found in the research regarding these topics.

Cold and Flu Prevention

Okay so the temperatures are now dropping and as they do you may be attempting to stand a far distance away from that sneezing person at your workplace. Have no fear - incorporating Vitamin C, Vitamin D and Probiotics has been shown to reduce the likelihood of you getting sick. 

1. Vitamin C

  • A 5 year trial found that 500mg of daily Vitamin C taken preventatively reduced the frequency of the common cold (1) 
  • Tip: Eat more red bell peppers, broccoli and fruits like kiwi for Vitamin C

2. Vitamin D

  • Supplementing Vitamin D deficient patients  up to an adequate Vitamin D  level resulted in a reduced frequency of cold-related work absences (2)
  • Tip: Vitamin D levels are important for immune health, mood regulation and disease prevention – check in with a Naturopath to see where your levels are at. Vitamin D testing is not covered under OHIP unless you are at risk for osteoporosis. A test through your MD or ND is around $35. 

3. Probiotics

  • Probiotics were shown to be superior to placebo in reducing the episodes of acute upper respiratory tract infections and decreased antibiotic use and school absences (3)
  • Probiotics are a very important adjunct to your health regime, and can help reduce dependence on antibiotics and sick days for you and your family!
  • Nourish your gut with these probiotic foods: Yogurt, Kefir, Kimchi, Sauerkraut and Komboucha

Cold and Flu Treatment

So let's say you couldn't avoid being in the vicinity of children with runny noses or the office/campus cold has finally hit you (despite you trying your best to avoid it like the plague!). 

1. Vitamin C

  • This vitamin does double duty when it comes to preventing and treating colds. A large trial found that 1 gram per day taken prophylactically during cold and flu season prevented the drop in leukocytes (white blood cells) that occurs and decreased the severity of common cold symptoms (5). In other words, taking Vitamin C regularly during cold and flu season can act as "treatment" if you do get sick, by making symptoms less intense. 

2. Zinc

  • Zinc supplementation was shown to decrease the symptom duration and severity score of the common cold (6)
  • Nutrition Tip: Up your dietary zinc intake by eating more red meat, seafood, pumpkin seeds, beans and lentils
  • Extra Tip: Come into the clinic for an in-office Zinc tally test (only at $3) to test your zinc levels.

Herbal Medicine

  • There are many botanical herbs that are effective in both preventing and treating a cold or flu. Some common ones used are: Echinacea, Astragalus, Reishi, Licorice and Andrographis. Wait for next week’s blog feature on Herbal Medicine for Immunity!

Do you need more guidance on creating your cold and flu treatment plan (frequent colds and infections, or not sure which to choose from)? Book in with Kaitlyn by clicking here.            



1.     Sasazuki et al (2006). Effect of vitamin C on common cold: randomized controlled trial. Eur J Clin Nutr.

2.     Schmidt & Zirkler (2011). Dietary efficacy of a micronutrient combination in patients with recurrent upper respiratory tract infections. Results of a placebo-controlled double-blind study. MMW Fortschr Med

3.     Quick (2015). Cochrane Commentary: Probiotics for Prevention of Acute Upper Respiratory Infection. Explore (NY).

4.     Anderson et al (1972). Vitamin C and the common cold: a double blind trial. Can Med Assoc J.

5.     Al-Nakib et al (1987). Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges. J Antimicrob Chemother.