Catching One Cold After the Other? 10,000 IU Vitamin D per Week + Gargling May Help. Plus: Gargling Thrice A Day or Gargling With Green Tea Are Even More Effective!

Gargling and vitamin D (10,000 IU/week) keep you infection free.
Not too long ago, everyone would have thought you'd picked the wrong letter from the vitamin alphabet if you told him to use "vitamin D" supplements to ward off upper respiratory infections. For decades this has been the still unconfirmed prerogative of vitamin C, which appears to work only in men & women with chronically low intakes of vitamin C...  These days, however, vitamin D can - supposedly - do everything and Mr. and Mrs. Joe & Jane Average won't be surprised to hear that Emma C Goodall and colleagues from the McMaster University and other research institutions call vitamin D, or to be more precise the provision of vitamin D3 supplements a promising intervention for the prevention of URTI. 
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To test their hypothesis that the combination of gargling in D-supplementation would ward off the common and not so common cold(s), the scientists randomized 600 students into 4 treatment arms:
  • vitamin  D and  no  gargling,  and  
  • placebo  and  no  gargling.  
  • vitamin D3 and gargling, 
  • placebo and  gargling,  
The students completed weekly electronic surveys and submitted self-collected mid-turbinate nasal flockedswabs during September and October in 2010 or 2011. Symptomatic students also completed
an electronic symptom diary, which was intended to test for possible effects of vitamin D on the severity and length of the upper respiratory tract infections (URTIs). The primary and secondary outcomes were the occurrence of symptomatic clinical URTI and laboratory confirmed URTI respectively.
Figure 1: Effect of gargling and vitamin D supplementation on URTI occurance (laboratory confirmed), viral load, symptom duration and symptom severity (Goodall. 2014)
As you'd expect, not all students completed the study - of 600 participants, only 471 (78.5%) completed all survey. 43 (7.2%) even registered without completed a single of the questionnaires. Of those students who did responde, 150 (25.0%) reported clinical upper respiratory tract infections (laboratory testing identified 70 infections; 46.7 per 100 URTIs).
And what about the gargling? It's surprising but even plain tap water helps reduce the incidence of upper-respiratory tract infections (-18%)... non-signifcantly, but it helps ;-) If you want to achieve significance and up the effectiveness from -18% to -46%, you would just have to do HIIT gargling, i.e. gargle the water for about 15 seconds three times consecutively, and do this at least three times a day - at least for the subjects in a 2005 study from the Kyoto University School of Public Health that worked like a charm (Satomura. 2005). And if you aim to minimize it by reducing your risk by ~90%, you can simply add some tea catechins (200 µg/mL catechins, 60% of catechins comprise epigallocatechin gallate) to your gargling water (Yamada. 2006).
If we look at the effects of vitamin D in isolation, we will see that seventy of those 150 participants had been randomized to the the vitamin D3 groups. The other 80 subjects, were in one of the "no-suppplementation" groups. Based on this data the scientists calculated a "significantly lower risk for laboratory confirmed URTI (RR: 0.54, CI95 :0.34-0.84, p = 0.007)" and "a significantly lower mean viral load  measured  as  log10 viral  copies  /  mL" for the vitamin D3 supplemented study participants.

Interestingly, these results stand in contrast to previous studies, where a different dosing scheme, i.e. 100,000IU/month of vitmamin D3 supplements, did not yield a significant reduction in URTI incidence among the 322 healthy adults who participated in a 2012 study by Murdoch et al. that was conducted between February 2010 and November 2011 in Christchurch, New Zealand and analyzed both the D-intake and the changes in 25-OHD levels (Murdoch. 2012).
SuppVersity Suggested Read: "Based on the Latest Evidence, Who Would Benefit From Even more Vitamin D? Plus: How Much Vitamin D Do I Need To Achieve Optimal Levels & Keep Them Steady? " | read more
Bottom Line: It's not unlikely that the dosing protocol, i.e. 100,000IU 1x per months vs. 10,000IU / week everyday made all the difference, here, but without a study to test the two directly against each other, we can only speculate if this or any other confounding factor made the difference (e.g. baseline 25OHD levels, etc.). If we look at other studies, e.g. 300IU/day in Mongolian children (Camargo. 2012) and 400IU/day in Finnish young men (Laaksi. 2010), it would yet not seem impossible - in spite of the fact that the latest reviews say confirm that "[r]esults from randomised controlled trials were conflicting however" (Jollife. 2013) and that currently available scientific evidence "do[es] not support the routine use of vitamin D supplementation for RTI prevention in healthy populations" (Mao. 2013).

That being said, I recently recommend taking ~1,000IU/day of vitamin D3 as a maintenance dose to keep your vitamin D levels in the normal range, year-round anyway. If you do that you would automatically get enough vitamin D to see the anti-upper-respiratory-tract effects - if there are any.
  • Goodall, Emma C., et al. "Vitamin D3 and gargling for the prevention of upper respiratory tract infections: a randomized controlled trial." BMC Infectious Diseases 14.1 (2014): 273.
  • Jolliffe, David A., Christopher J. Griffiths, and Adrian R. Martineau. "Vitamin D in the prevention of acute respiratory infection: systematic review of clinical studies." The Journal of steroid biochemistry and molecular biology 136 (2013): 321-329.
  • Laaksi, Ilkka, et al. "Vitamin D supplementation for the prevention of acute respiratory tract infection: a randomized, double-blinded trial among young Finnish men." Journal of Infectious Diseases 202.5 (2010): 809-814. 
  • Mao, Song, and Songming Huang. "Vitamin D supplementation and risk of respiratory tract infections: A meta-analysis of randomized controlled trials." Scandinavian journal of infectious diseases 45.9 (2013): 696-702.
  • Murdoch, David R., et al. "Effect of Vitamin D3 Supplementation on Upper Respiratory Tract Infections in Healthy AdultsThe VIDARIS Randomized Controlled TrialVitamin D3 and Upper Respiratory Tract Infections." Jama 308.13 (2012): 1333-1339.
  • Satomura, Kazunari, et al. "Prevention of upper respiratory tract infections by gargling: a randomized trial." American journal of preventive medicine 29.4 (2005): 302-307.
Disclaimer:The information provided on this website is for informational purposes only. It is by no means intended as professional medical advice. Do not use any of the agents or freely available dietary supplements mentioned on this website without further consultation with your medical practitioner.