Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: a systematic review and meta-analysis
BMJ Glob Health . 2021 Jan;6(1):e003176. doi: 10.1136/bmjgh-2020-003176.
Ajibola Ibraheem Abioye 1, Sabri Bromage 2, Wafaie Fawzi 3
Subset of table
- Colds and flu prevented and treated by Vitamin D - many studies
- Respiratory infections reduced by 63 percent with 4000 IU vitamin D daily - RCT Dec 2012
- Acute respiratory tract infections not reduced by Vitamin D if already have a good level – Jan 2020
- Respiratory deaths in seniors – 40 percent are attributable to low vitamin D – Aug 2020
- Respiratory infections cut in half by 20,000 IU weekly vitamin D if initially deficient – RCT March 2015
- RTI – Feel much better if increase vitamin D level above 40 ng (4000 IU) – RCT Sept 2015
- Respiratory Tract visits 2.5 less likely with vitamin D: Pregnancy 2000 IU, Infant 800 IU – RCT Oct 2014
- Acute viral respiratory infections reduced by Vitamin D - overview of 20 reviews - Aug 2020
- Respiratory infections reduced only 20 percent by Vitamin D (ignored dose size, duration, type, etc) – meta-analysis Jan 2019
Items in both categories Breathing and Loading Dose are listed here:
- Childhood asthma problems eliminated for months by 600,000 IU of Vitamin D injection – June 2017
- Pneumonia in children not stopped for 6 months by single dose of vitamin D (3 months max) – RCT Nov 2016
- 500,000 IU of vitamin D cut in half the hospital days following a lung failure – RCT 2015
- 5 days of 100,000 IU of Vitamin D increased hemoglobin in critical illness – RCT April 2015
- Recurrence of child pneumonia delayed by 100000 IU of vitamin D – RCT Oct 2010
Acute respiratory tract infections (ARIs) are a leading cause of ill-health and death globally. Individual or multiple micronutrients have been shown to modulate immune function and affect the risk and severity of a number of infectious diseases. We systematically reviewed the evidence on the impact of micronutrient supplements to reduce the occurrence of ARIs and shorten the duration of ARI symptoms among adults. Random effects meta-analyses were conducted to estimate the pooled effects of vitamin D, vitamin C, zinc and multiple micronutrient supplementation (MMS) on the occurrence of ARIs and the duration of ARI symptoms. Vitamin D supplementation reduced the risk of ARI (risk ratio (RR)=0.97; 95% CI 0.94 to 1.00; p=0.028) and shortened the duration of symptoms (per cent difference: -6% (95% CI -9% to -2%; p=0.003)).
The RR of vitamin D to prevent ARI was farther from the null when diagnosis was based on clinical diagnosis or laboratory testing, compared with self-report and when the loading dose was <60 000 IU.
Vitamin C supplementation reduced the risk of ARIs (RR=0.96; 95% CI 0.93 to 0.99; p=0.01) and shortened the duration of symptoms (per cent difference: -9% (95% CI -16% to -2%; p=0.014)). The effect of vitamin C on preventing ARI was stronger among men and in middle-income countries, compared with women and high-income countries, respectively.
Zinc supplementation did not reduce the risk of ARIs but shortened the duration of symptoms substantially (per cent difference: -47% (95% CI -73% to -21%; p=0.0004)).
Our synthesis of global evidence from randomised controlled trials indicates that micronutrient supplements including zinc, vitamins C and D, and multiple micronutrient supplements may be modestly effective in preventing ARIs and improving their clinical course. Further research is warranted to better understand the effectiveness that individual or multiple micronutrients have on SARS-CoV-2 infection and treatment outcomes.