What do Cochrane systematic reviews say about interventions for vitamin D supplementation?
Sao Paulo Med. J. vol.135 no.5 São Paulo Sept./Oct. 2017 Epub Nov 06, 2017
Mariana Vendramin MateussiI, Carolina de Oliveira Cruz LatorracaII, Júlia Pozetti DaouI, Ana Luiza Cabrera MartimbiancoIII, Rachel RieraIV, Rafael Leite PachecoI, Daniela Vianna PachitoV,
Cochrane reviews typically look at outcomes across a huge range of Vitamin D interventions
- From 400 IU daily to 10,000 IU daily
- From no loading dose to loading dose of 600,000 IU
- From daily to yearly
- From 8 weeks to a year or more
Thus typically the good results are swamped out by poor dosing schemes
Imagine having a Cochrane review of aspirin for headaches
which averaged the responses of 1 mg of Aspirin with 325 mg.
The review would conclude, that on average, aspirin does not help headaches.
Apparently a few of the Cochrane reviews of Vitamin D intervention ignored ineffective dosing
Note: Preterm birth rates were reduced 60%  Download the PDF from VitaminDWiki
when they averaged over a range of 200 IU/day to 2000 IU/day
which did not even include the 4,000 IU/day doses that are typically being used
See also VitaminDWiki
- Preterm birth rate reduced 57 percent by Vitamin D – Nov 2015
- Preterm birth rate reduced by vitamin D – 78 percent if non-white, 39 percent if white – July 2017
- Preterm birth rate reduced by 43 percent with adequate Vitamin D supplementation – meta-analysis Feb 2017
- How employers can save a million dollars per 1000 pregnancies - just by reduction in preterm births
- Preterm birth rates increased in 15 European countries – Oct 2013
CONTEXT AND OBJECTIVE: Despite the high prevalence of vitamin D supplementation, its use remains controversial. The objective of this review was to identify and summarize the evidence from Cochrane systematic reviews regarding vitamin D supplementation for preventing ortreating any clinical condition.
DESIGN AND SETTING: Review of systematic reviews, conducted in the Discipline of Evidence-Based Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo.
METHODS: A search was conducted to identify all Cochrane systematic reviews that fulfilled the inclusion criteria. Titles and abstracts were screened by two authors.
RESULTS: We included 27 Cochrane systematic reviews: 10 assessing use of vitamin D for prevention and 17 for treatment. The reviews found moderate to high quality of evidence regarding the benefit of vitamin D for pregnant women (
- prevention of adverse events: preterm birth risk
[rate ratio, RR 0.36; 95% confidence interval, CI 0.14 to 0.93] and
- low birthweight risk [RR 0.40; 95% CI 0.24 to 0.67]) and for
- asthma patients (reduction of severe exacerbations [RR 0.63; 95% CI 0.45 to 0.88]).
No benefit was found regarding vitamin D supplementation alone (without calcium) for preventing hip or any new fracture. For all other outcomes assessed under various conditions, the current quality of evidence is low or unknown, and therefore insufficient for any recommendation.
CONCLUSION: Based on moderate to high quality of evidence, the Cochrane systematic reviews included here showed that there were some benefits from vitamin D supplementation for pregnant women and asthma patients and no benefits for preventing fractures.