08/01/2020
A Research Literature Based Review on Vitamin D’s Effects on Respiratory Tract Infections and Immune Resilience
(Be warned: This is a long read, but worth looking at scientific factual information on this important topic. Nothing presented here is intended as providing medical advice but only as educational information.) There has been much misinformation regarding the effects of vitamin D on upper respiratory tract infections, including recommended vitamin D dosing, and immune resilience within the first eight months of 2020. Therefore, let’s look strictly at research literature for the science on this topic.
Whenever possible I am citing systematic reviews and meta-analysis. Systematic reviews are a selection of critically appraised scientific studies that review evidence on a clearly formulated question to extract and analyze data from studies in the review. A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Many times, but not always, a meta-analysis is a component of a systematic review.
I've added a research conclusions summary at the end for the convenience of those who don't want to read through the study details.
In a meta-analysis study, 8 observational studies involving 20,966 subjects concluded those with Vitamin D deficiency of less than 20 ng/mL serum vitamin D are 1.64 times more likely of having community acquired pneumonia than those with over 20 mg/mL serum vitamin D. Zhou YF, Luo BA, Qin LL. The association between vitamin D deficiency and community-acquired pneumonia: A meta-analysis of observational studies. Medicine (Baltimore). 2019;98(38):e17252.
In a meta-analysis study, 32 observational studies concluded that serum 25(OH)D concentrations less than or equal to 30 ng/mL had 1.9 times higher all-cause mortality than those with serum concentrations greater than 30 ng/mL. Garland CF, Kim JJ, Mohr SB, et al. Meta-analysis of all-cause mortality according to serum 25-hydroxyvitamin D. Am J Public Health. 2014;104(8):e43–e50.
In a systematic review and meta-analysis of Vitamin D and respiratory tract infections, 11 studies met the final analysis criteria involving 5660 patients of an average age of 16 years. The average vitamin D3 dose was 1600 IU/day. The dose interval varied between 24 hours and 3 months. The summarized results of the 11 included randomized trials indicates that supplementation with vitamin D significantly reduces the risk of respiratory tract infections. Bergman P, Lindh AU, Björkhem-Bergman L, Lindh JD. Vitamin D and Respiratory Tract Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS One. 2013;8(6):e65835.
In a prospective, randomized, double-blind placebo-controlled study of vitamin D3 supplementation in patients between 18 and 75 years old with an increased susceptibility to respiratory tract infections, 70 patients received 4000 IU vitamin D3 daily for 1 year, and 70 patients got a placebo. After 3 months, those in the vitamin D group had serum 25(OH) D levels of 53 compared to 26 in the placebo group. The findings of the study were that vitamin D3 reduced the total infectious score by 23% during the study year. Bergman P, Norlin A, Hansen S, et al Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention studyBMJ Open 2012;2:e001663.
In a study of patients with Acute Respiratory Distress Syndrome (ARDS), 100% of the patients had a serum 25(OH)D3 level under 20 ng/mL. In this study, 25(OH)D3 were significantly lower in those patients who were ventilated with ARDS postoperatively (ARDS 6.8 ng/mL). The odds of ARDS in patients with 25(OH)D3