Prevention of covid-19 and other acute respiratory infections with cod liver oil supplementation, a low dose vitamin D supplement: quadruple blinded, randomised placebo controlled trial
RCT 17,278 low-risk patients (zero mortality) treated with 5mL/day cod liver oil (~400IU vitamin D) and 17,323 placebo patients in Norway with, showing no significant differences with treatment. The placebo group had higher vitamin D at baseline, and both groups had comparable vitamin D during treatment (74 vs. 63 nmol/L). 23% of control patients took vitamin D supplements and 62% consumed fatty fish (typically a good source of vitamin D). Adherence was low (<70% for "strict" compliance, which only required >0.5L consumed, or treatment for > "2-3" months).
risk of ICU admission, 0.3% higher, RR 1.00, p = 1.00, treatment 4 of 17,278 (0.0%), control 4 of 17,323 (0.0%).
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risk of hospitalization, 10.9% lower, RR 0.89, p = 1.00, treatment 8 of 17,278 (0.0%), control 9 of 17,323 (0.1%), NNT 17692.
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risk of severe case, 20.0% higher, RR 1.20, p = 0.17, treatment 121 of 17,278 (0.7%), control 101 of 17,323 (0.6%).
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risk of case, no change, RR 1.00, p = 0.98, treatment 227 of 17,278 (1.3%), control 228 of 17,323 (1.3%), NNT 42377.
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Effect extraction follows pre-specified rules prioritizing more serious outcomes. Submit updates
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Brunvoll et al., 7 Sep 2022, Double Blind Randomized Controlled Trial, placebo-controlled, Norway, peer-reviewed, mean age 44.9, 15 authors, study period 10 November, 2020 - 2 June, 2021, dosage 400IU daily, this trial uses multiple treatments in the treatment arm (combined with cod liver oil) - results of individual treatments may vary, trial
NCT04609423 (history).
Contact:
arne@meg.no.
Abstract: RESEARCH
Sonja H Brunvoll,1 Anders B Nygaard,1 Merete Ellingjord-Dale,1 Petter Holland,1
Mette Stausland Istre,1 Karl Trygve Kalleberg,2 Camilla L Søraas,3 Kirsten B Holven,4,5
Stine M Ulven,4 Anette Hjartåker,4 Trond Haider,6 Fridtjof Lund-Johansen,7 John Arne Dahl,1
Haakon E Meyer,8,9 Arne Søraas1
For numbered affiliations see
end of the article
Correspondence to: A Søraas
arne@meg.no
(ORCID 0000-0003-1622-591X)
Additional material is published
online only. To view please visit
the journal online.
Cite this as: BMJ 2022;378:e071245
http://dx.doi.org/10.1136/
bmj‑2022‑071245
Accepted: 19 July 2022
Abstract
Objective
To determine if daily supplementation with cod liver
oil, a low dose vitamin D supplement, in winter,
prevents SARS-CoV-2 infection, serious covid-19, or
other acute respiratory infections in adults in Norway.
Design
Quadruple blinded, randomised placebo controlled
trial.
Setting
Norway, 10 November 2020 to 2 June 2021.
Participants
34 601 adults (aged 18-75 years), not taking daily
vitamin D supplements.
Intervention
5 mL/day of cod liver oil (10 µg of vitamin D,
n=17 278) or placebo (n=17 323) for up to six months.
Main outcome measures
Four co-primary endpoints were predefined: the first
was a positive SARS-CoV-2 test result determined
by reverse transcriptase-quantitative polymerase
chain reaction and the second was serious covid-19,
defined as self-reported dyspnoea, admission to
hospital, or death. Other acute respiratory infections
were indicated by the third and fourth co-primary
endpoints: a negative SARS-CoV-2 test result and
self-reported symptoms. Side effects related to the
supplementation were self-reported. The fallback
method was used to handle multiple comparisons.
What is already known on this topic
Vitamin D has been suggested as having a role in the prevention of covid-19, but
most studies have been observational
A recent meta-analysis of 46 randomised controlled trials showed that vitamin
D supplementation decreased the risk of acute respiratory infections compared
with placebo, but the effect was small
What this study adds
Of 34 601 unselected adult participants, no difference in the incidence of SARSCoV-2 infection, serious covid-19, or acute respiratory infections was found for
those randomised to daily supplements of low dose vitamin D (cod liver oil) or
placebo (corn oil) during the winter
The cod liver oil and placebo group had similar side effects, and only low grade
side effects were reported
the bmj | BMJ 2022;378:e071245 | doi: 10.1136/bmj-2022-071245
Results
Supplementation with cod liver oil was not associated
with a reduced risk of any of the co-primary endpoints.
Participants took the supplement (cod liver oil or
placebo) for a median of 164 days, and 227 (1.31%)
participants in the cod liver oil group and 228 (1.32%)
participants in the placebo group had a positive
SARS-CoV-2 test result (relative risk 1.00, multiple
comparison adjusted confidence interval 0.82 to
1.22). Serious covid-19 was identified in 121 (0.70%)
participants in the cod liver oil group and in 101
(0.58%) participants in the placebo group (1.20,
0.87 to 1.65). 8546 (49.46%) and 8565 (49.44%)
participants in the cod liver oil and placebo groups,
respectively, had ≥1 negative SARS-CoV-2 test results
(1.00, 0.97 to 1.04). 3964 (22.94%) and 3834
(22.13%) participants in the cod liver oil and placebo
groups, respectively, reported ≥1 acute respiratory
infections (1.04, 0.97 to 1.11). Only low grade side
effects were..
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