VDC test kit slider

RCT discovers vitamin D supplementation decreases microbial activity within the respiratory system

Posted on: September 29, 2017   by  Riley Peterson & John Cannell, MD.


The immune system is a complex, yet efficient, barrier against harmful pathogens trying to enter the human body. The immune system’s first line of defense is made up of external barriers that protect the body, primarily the skin. The second line of defense is much more specialized, and is triggered by the entrance of foreign cells into the body. One important component of the second line of defense is innate, or nonspecific, immunity. The innate immune system attacks and destroys these pathogens that break past the first line of defense.

The respiratory system relies on the immune system to protect the airway, as the oral and nasal cavities are both easily accessible spots for pathogens to enter. The trachea is lined with a mucous layer called airway surface liquid (ASL), which is meant to protect the respiratory tract from infection. A major component of ASL are antimicrobial peptides, which are part of the innate immune response against foreign cells and pathogens.

Vitamin D regulates the production of antimicrobial peptides, leading researchers to theorize that vitamin D status may play a role in respiratory tract infections. There has been an abundance of research that has linked low vitamin D status to increased occurrence of respiratory infections. Additionally, vitamin D supplementation has been shown to decrease the frequency of upper respiratory tract infections. Yet, there has been no research to date that has evaluated the role of vitamin D supplementation on ASL in healthy individuals. Therefore, researchers decided to explore the effect of vitamin D supplementation on lung immunity in a single-centre, community-based, randomized, placebo-controlled double-blind trial. 

You must be a paid member to read the rest of this post. Please login or register now.


Peterson, R. RCT discovers vitamin D supplementation decreases microbial activity within the respiratory system. The Vitamin D Council Blog & Newsletter, 9/2017.


Vargas Buonfigilo, LG. et al. Effect of vitamin D3 on the antimicrobial activity of human airway surface liquid: preliminary results of a randomised placebo-controlled double-blind trial. BMJ Open Respiratory Research, 2017.


2 Responses to RCT discovers vitamin D supplementation decreases microbial activity within the respiratory system

  1. robertjmjrs38499500

    What I am reading in this article ends with “double blind trial.” Then it states I must be a member and logged in to read the rest of the article, which I was both. Is there a conclusion to this article. Does it end that way or is there something else I must do to see the rest of it?lease answer me by email. [email protected]. Thank you.

  2. cristinamlea84530100

    Before to start vit D supplement my level of vit D (found with your effective kit test) was borderline at the minimum. Infact that year (3 years ago) I’ve been heavily ill 3 times, all together with the duration of 4 months and a half and lots of antibiotics. Therefore, after your test and a lot of reserces, I decided to take everyday 2500 IU OF VIT D. Now my vit D level is at the maximum and it seems that my body is much lesss susceptible to cold and chest infection, infact since then I’ve been well enough and if I catch something I’m able to get over it only with natural products like Echinacea, propolis, vit C etc, without any chemical drug. I’m very happy of all that, considering that I’m 67 years old. So far so good. THANKS VITAMIN D COUNCIL FOR YOUR VALID ADVICES!!!

Test Your Vitamin D Levels at Home!

Our in-home vitamin D test kit is easy, affordable, and an accurate way to find out your Vitamin D status.

order NOW

We need your help!

We're spreading awareness on Vitamin D Deficiency
Donate NOW
Latest Articles
What is the relationship between vitamin D and childhood UTIs?

A new study suggests vitamin D may protect against UTIs among children by upregulating their own naturally occurring antimicrobial peptides.

Weekly Newsletter

Our Sponsors

December 21st is DDAY. Click here to celebrate the day with us!