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Two large studies from the UK and Norway show. Vitamin D Low-dose, high-dose, or supplementation in the form of cod liver oil supplementation, whether deficient or not, has no benefit in preventing COVID-19 or acute respiratory infections.
Research published this week BMJMore“Vaccination remains the most effective way to protect people from COVID-19, and vitamin D and cod liver oil supplementation should not be offered to healthy people with normal vitamin D levels,” Karolinska said. Peter Bergmann, M.D., writes The Institute, Stockholm, Sweden, editorial Published with research.
Suboptimal levels of vitamin D are known to be associated with increased acute risk. respiratory infections, and some observational studies have associated low 25-hydroxyvitamin D (25(OH)D) with more severe COVID-19. However, data regarding possible protective effects of vitamin D supplementation in preventing infection are inconsistent.
UK study compares doses
To further explore its relationship to infectious diseases, including COVID-19, in a large cohort, first time of 2 BMJMore The study, a Phase 3 open-label trial, enrolled 6,200 UK people aged 16 and over who were not taking vitamin D supplements at baseline between December 2020 and June 2021. rice field.
Half of the participants had a fingertip blood test, and 86.3% of the 2674 accepted were found to have low levels of 25(OH)D (< 75 nmol/L). These participants were provided with low-dose (800 IU/day; n = 1328) or high-dose (3200 IU/day; n = 1346) vitamin D supplementation for 6 months. The other half of the group received no tests or supplements.
Results showed minimal between-group differences in the incidence of at least one acute respiratory infection. This occurred in 5% of the low-dose group, 5.7% of the high-dose group, and his 4.6% of participants who were not provided. replenishment.
Similarly, there was no significant difference in incidence of real-time PCR-confirmed COVID-19, with rates of 3.6% in the low-dose group, 3.0% in the high-dose group, and 2.6% in the non-offered group. replenishment.
This study is “the first phase 3 randomized controlled trial to evaluate the efficacy of test-and-treatment approaches to modify suboptimal vitamin D status to prevent acute respiratory infections.” report the authors, led by Adrian R. Martineau, MD. PhD, Barts and Queen of London Medical and Dental College, He Mary University, UK.
Although intake and supplementation were good in this study, there were no “primary outcomes of swab-confirmed or physician-confirmed acute respiratory infections or primary secondary outcomes of swab-confirmed COVID-19.” No statistically significant effect was seen at any dose,” they conclude.
Traditional Uses of Cod Liver Oil for Benefits?
Secondly studyNorwegian researchers led by Arne Soraas, MD, PhD, Department of Microbiology, University of Oslo Hospital, found that the long-standing Norwegian tradition of consuming cod liver oil in the winter to prevent vitamin D deficiency was associated with the development of vitamin D deficiency. We evaluated whether it could have an impact. COVID-19 or results.
The Cod Liver Oil for COVID-19 Prevention Study (CLOC) randomized a large cohort of 34,601 adults with a mean age of 44.9 years who were not taking daily vitamin D supplements to receive 5 mL of cod liver oil daily. was ingested. A surrogate dose of 400 IU/day vitamin D (n = 17,278), or placebo (n = 17,323) for up to 6 months.
In contrast to the first study, the majority (86%) of patients in the CLOC study had adequate vitamin D levels, defined as >50 nmol/L at baseline.
However, the results show no association between increased vitamin D supplementation with cod liver oil and PCR-confirmed COVID-19 or acute respiratory infections, with a median of 164 days for each group. Approximately 1.3% of those tested positive for COVID-19.
Cod liver oil supplementation was not associated with risk reduction for any of the primary endpoints, including other acute respiratory infections.
“Daily supplementation of cod liver oil, low-dose vitamin D, eicosapentaenoic acid, and docosahexaenoic acid for 6 months during SARS-CoV-2
The pandemic among Norwegian adults did not reduce the incidence of SARS-CoV-2 infection, severe COVID-19, or other acute respiratory infections,” the authors report.
Main study limitations
In his editorial, Bergman highlights the limitations of the two studies, including the important role of vaccine confounding that was revealed during the study. The author also acknowledges this.
“The results obtained in these studies should be interpreted in the context of the highly effective vaccines deployed in both studies,” Bergman wrote.
For example, in a UK study, only 1.2% of participants received vaccinations at baseline, while by the end of the study the proportion of participants who had received at least one dose jumped to 89.1%, with vitamin D’s effect may be hidden, he says.
Additionally, in a Norwegian study, Bergmann found that cod liver oil also contained significant amounts of Vitamin Acan be potent immunomodulators.
“Excessive intake of vitamin A can cause adverse effects and may also interfere with vitamin D-mediated effects on the immune system,” he writes.
Two recent large-scale meta-analyses have shown that the benefits of vitamin D supplementation are particularly seen in people with vitamin D deficiency, suggesting that “a practical approach for clinicians is to focus on risk groups. ,” writes Bergman.
“[These include] People with dark skin, people who don’t get much sunlight, pregnant women, elderly people with chronic diseases, etc., who were able to test before taking the supplement.
The UK study was supported by Barts Charity, Pharma Nord, Fischer Family Foundation, DSM Nutritional Products, Exilarch’s Foundation, Karl R. Pfleger Foundation, AIM Foundation, Synergy Biologics, Cytoplan and the UK National Laboratory Clinical Research Network . Health and Care Research, HDR UK BREATHE Hub, UK Research and Innovation Industrial Strategy Challenge Fund, Thornton & Ross, Warburtons, Hyphens Pharma and philanthropist Matthew Isaacs.
The CLOC trial was funded by Orkla Health, the manufacturer of the cod liver oil used in the trial. No related financial relationships have been reported.
BMJ. Published online on September 7, 2022.
