Cochrane reviews and comments on Cochrane reviews

Department of Public Health
University of Helsinki, Finland
harri.hemila@helsinki.fi
http://www.mv.helsinki.fi/home/hemila
Jan 31, 2025

Cochrane reviews on vitamin C
Various problems and flaws in other Cochrane reviews

Cochrane reviews on vitamin C

The common cold

On Jan 2025, this review had the Altmetric score 4427
https://cochrane.altmetric.com/details/1229303

On Oct 2022, this review had the Altmetric score 3382, which was position 1439 out of all the 22,246,158 outputs, and 5th of the Cochrane reviews:
https://www.mv.helsinki.fi/home/hemila/AltmetricVitC_Colds_2022Oct.htm#score

Cochrane Database Syst Rev 2013; CD000980
https://pmc.ncbi.nlm.nih.gov/articles/PMC8078152
https://hdl.handle.net/10138/225864
https://doi.org/10.1002/14651858.cd000980.pub4
https://www.mv.helsinki.fi/home/hemila/CC/2013_Coch_Colds_CD000980.pdf
https://www.ncbi.nlm.nih.gov/pubmed/23440782

References to the review:
https://www.mv.helsinki.fi/home/hemila/CC

Commentaries on ‘Vitamin C for Preventing and Treating the Common Cold’ with a response from the review author
   [Reply to Bax, Spee and Madderom].
     [Reply to Shamseer and Vohra].
     Evidence-Based Child Health: A Cochrane Review Journal 2008;3:724-728
https://www.researchgate.net/publication/244785237
https://hdl.handle.net/10138/228088
https://doi.org/10.1002/ebch.261
https://www.mv.helsinki.fi/home/hemila/H/2008_L_EBCH.pdf

Pneumonia

Three controlled trials have found significant decrease in the incidence of pneumonia and two found treatment benefit for pneumonia patients.
Hemilä H, Louhiala P.
Vitamin C for preventing and treating pneumonia.
Cochrane Database Syst Rev 2013; CD005532
https://hdl.handle.net/10138/225862
https://www.mv.helsinki.fi/home/hemila/CP/2013_Coch_Pneu_CD005532.pdf
https://doi.org/10.1002/14651858.cd005532.pub3
https://pubmed.ncbi.nlm.nih.gov/23925826/

References to the review:
https://www.mv.helsinki.fi/home/hemila/CP/

Tetanus

Hemilä H, Koivula TT
Vitamin C for preventing and treating tetanus.
Cochrane Database Syst Rev 2013; CD006665
https://hdl.handle.net/10138/225863
https://doi.org/10.1002/14651858.cd006665.pub3
https://www.mv.helsinki.fi/home/hemila/CT/2013_Coch_Tetanus_CD006665.pdf
https://pubmed.ncbi.nlm.nih.gov/24226506/

References to the review:
https://www.mv.helsinki.fi/home/hemila/CT/

Various problems and flaws in other Cochrane reviews

Cochrane review on zinc and the common cold (2024) had a very large number of flaws:

Hemilä H, Chalker E.
Shortcomings in the Cochrane review on zinc for the common cold (2024).
Front Med (Lausanne). 2024
https://doi.org/10.3389/fmed.2024.1470004
https://pmc.ncbi.nlm.nih.gov/articles/PMC11521859

Longer version describing the details of the flaws:

Hemilä H.
Shortcomings in the Cochrane review on zinc and the common cold by Nault et al. (2024).
Zenodo.
https://doi.org/10.5281/zenodo.13762569

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Cochrane has not consistently followed the COPE guidelines - THERE WAS NO RESPONSE TO THIS CRITICISM
Eur J Clin Invest 2020
https://doi.org/10.1111/eci.13216
https://pubmed.ncbi.nlm.nih.gov/32077498

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Flaws in a 2020 Cochrane review on vitamin C and pneumonia:
Hemilä H, Chalker E.
Commentary: Vitamin C supplementation for prevention and treatment of pneumonia.
Front Med 2021
https://doi.org/10.3389/fmed.2020.595988
https://www.ncbi.nlm.nih.gov/pmc/articles/pmc7854566/

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Pointing out errors in the Cochrane review and a meta-analysis of 3 exercise-induced asthma trials
The meta-analysis was expanded to BMJ Open paper in 2013
The Cochrane review on vitamin C and asthma misled readers for a decade from 2001 to 2013
Hemilä H. Feedback [on the Cochrane review “vitamin C supplementation for asthma” (2009) by Kaur B, Rowe BH, Stovold E]
Cochrane Database of Systematic Reviews CD000993 [Feedback 24 March 2009]
https://helda.helsinki.fi/handle/10138/38500
https://doi.org/10.13140/2.1.1280.3364
    The above comment was submitted in 2009, but the authors replied no earlier than in 2012.
    Furthermore, the reply was full of errors:
    Hemilä H
    Vitamin C and exercise-induced bronchoconstriction:
    further problems in the Cochrane review "vitamin C for asthma" (2013).
    Unpublished commentary
    http://hdl.handle.net/10138/40816

The Cochrane review on vitamin C and asthma misled readers for a decade from 2001 to 2013.
See the PubMed records of the Cohrane review on vitamin C and asthma from 2001 to 2013:
https://pubmed.ncbi.nlm.nih.gov/11687089/   2001
https://doi.org/10.1002/14651858.CD000993
ss
https://pubmed.ncbi.nlm.nih.gov/15266435/   2004
https://doi.org/10.1002/14651858.CD000993.pub2

https://pubmed.ncbi.nlm.nih.gov/19160185/ 2009
https://doi.org/10.1002/14651858.CD000993.pub3

https://pubmed.ncbi.nlm.nih.gov/24155047/   2013 Withdrawal of the Cochrane review
https://doi.org/10.1002/14651858.CD000993.pub4

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Hemilä H
Oseltamivir (Tamiflu) shortens the duration of influenza-like illness by 13% (95% CI: 8% to 18%)
[Feedback on the Cochrane review “Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children” by Jefferson T et al.]
Cochrane Database of Systematic Reviews CD008965 [Feedback 6 May 2013]
https://helda.helsinki.fi/handle/10138/42534
https://doi.org/10.1002/14651858.CD008965.pub3

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Problems in the 2011 version of Cochrane review:
Hemilä H.
The zinc for the common cold review by Singh and Das has a number of problems which should be considered when the review is next time updated.
[Feedback on the Cochrane review “Zinc for the common cold review” by Singh and Das]. 2011.
Cochrane Database of Systematic Reviews CD001364 [Feedback 5 September 2011]
Repository of the University of Helsinki
https://helda.helsinki.fi/handle/10138/39188
https://doi.org/10.13140/2.1.4688.2081

Problems in the 2013 version of Cochrane review:
Hemilä H.
Concerns about unattributed copying of text and data, and about numerous other problems in the Cochrane review “Zinc for the Common Cold” by Singh M, Das RR (2013). 2015
Repository of the University of Helsinki
https://hdl.handle.net/10138/153180
https://doi.org/10.5281/zenodo.6394116

    The above comment led to the withdrawal of the Cochrane review, see:
    https://www.cochrane.org/CD001364/ARI_zinc-common-cold
    https://doi.org/10.1002/14651858.CD001364.pub5

The withdrawal of the Cochrane review also led to the retraction of a JAMA summary of the Cochrane review:

Hemilä H.
Common Cold Treatment Using Zinc.
JAMA. 2015;314(7):730.
https://doi.org/10.1001/jama.2015.8174
https://www.ncbi.nlm.nih.gov/pubmed/26284728

    The above JAMA letter pointed out problems in an article by Das and Singh, which was a summary of their Cochrane review.
    As their Cochrane review was withdrawn, their JAMA article was retracted:
    https://doi.org/10.1001/jama.2016.18134
    https://www.ncbi.nlm.nih.gov/pubmed/28027374

    More detailed problems in the Das and Singh JAMA article were described in a longer document:
    https://hdl.handle.net/10138/153617
    https://doi.org/10.5281/zenodo.6393782

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Hemilä H
Antioxidants are not identical and their effects are not uniform over the population.
[Feedback on the Cochrane review “Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases” by Bjelakovic G et al.]
Cochrane Database of Systematic Reviews CD007176 [Feedback 24 August 2009]

https://helda.helsinki.fi/handle/10138/136201
https://doi.org/10.13140/2.1.4426.0641
https://doi.org/10.1002/14651858.CD007176.pub2