Summary of COVID-19 vitamin A studies

1. Chung et al., A Pilot Study of Short-Course Oral Vitamin A and Aerosolised Diffuser Olfactory Training for the Treatment of Smell Loss in Long COVID

24 patient vitamin A long COVID RCT: 75% lower PASC (p=0.05).
RCT 24 patients with olfactory dysfunction post-COVID-19 in Hong Kong, showing significantly improved recovery with the addition of vitamin A to aerosolised diffuser olfactory training. 25,000IU vitamin A for 14 days.
Jun 2023, Brain Sciences, https://www.mdpi.com/2076-3425/13/7/1014, https://c19p.org/chung

2. Beigmohammadi et al., The effect of supplementation with vitamins A, B, C, D, and E on disease severity and inflammatory responses in patients with COVID-19: a randomized clinical trial

60 patient vitamin A ICU RCT: 89% lower mortality (p=0.11), 41% lower hospitalization (p=0.25), and 45% improved recovery (p=0.001).
Small RCT 60 ICU patients in Iran, 30 treated with vitamins A, B, C, D, and E, showing significant improvement in SOFA score and several inflammatory markers at day 7 with treatment. 5,000 IU vitamin A daily, 600,000 IU vitamin D once, 300 IU of vitamin E twice a day, 500 mg vitamin C four times a day, and one ampule daily of B vitamins [thiamine nitrate 3.1 mg, sodium riboflavin phosphate 4.9 mg (corresponding to vitamin B2 3.6 mg), nicotinamide 40 mg, pyridoxine hydrochloride 4.9 mg (corresponding to vitamin B6 4.0 mg), sodium pantothenate 16.5 mg (corresponding to pantothenic acid 15 mg), sodium ascorbate 113 mg (corresponding to vitamin C 100 mg), biotin 60 μg, folic acid 400 μg, and cyanocobalamin 5 μg].
Nov 2021, Trials, https://link.springer.com/article/10.1186/s13063-021-05795-4/fulltext.html, https://c19p.org/beigmohammadi2a

3. Wang et al., Retinol and retinol binding protein 4 levels and COVID-19: a Mendelian randomization study

vitamin A prophylaxis study: 35% lower severe cases (p=0.28), 24% lower hospitalization (p=0.29), and 31% fewer cases (p=0.006).
Mendelian randomization study suggesting a causal association between retinol and related proteins (RBP4, RDH16, CRABP1) and COVID-19. The study found that genetically-predicted higher retinol levels were associated with lower COVID-19 susceptibility. There was a lower risk of hospitalization and severity without statistical significance. Authors conclude that the results support a potential protective effect of vitamin A treatment for COVID-19. Given the lack of clear evidence for pleiotropy, and the lower precision of the MR-Egger estimates, the IVW estimates are likely more reliable in this case when the IVW and MR-Egger estimates differ.
Apr 2024, BMC Pulmonary Medicine, https://bmcpulmmed.biomedcentral.com/articles/10.1186/s12890-024-03013-w, https://c19p.org/wang31

4. Rohani et al., Evaluation and comparison of the effect of vitamin A supplementation with standard therapies in the treatment of patients with COVID-19

180 patient vitamin A early treatment RCT: 26% lower hospitalization (p=0.63) and 32% improved recovery (p=0.53).
RCT 91 vitamin A and 91 control patients in Iran, showing improved recovery with treatment. All patients received HCQ. 25,000IU/day oral vitamin A for 10 days.
Aug 2022, Eastern Mediterranean Health J., http://www.emro.who.int/in-press/research/evaluation-and-comparison-of-the-effect-of-vitamin-a-supplementation-with-standard-therapies-in-the-treatment-of-patients-with-covid-19.html, https://c19p.org/rohani

5. Taheri et al., Therapeutic effects of olfactory training and systemic vitamin A in patients with COVID-19-related olfactory dysfunction: a double-blinded randomized controlled clinical trial

60 patient vitamin A late treatment RCT: 38% improved recovery (p=0.53).
RCT 90 outpatients with post-COVID-19 anosmia showing significant improvements in smell alterations with olfactory training after 3 and 12 months. Adding oral vitamin A to olfactory training resulted in higher rates of improvement, but the difference was not statistically significant.
Jun 2024, Brazilian J. Otorhinolaryngology, https://www.sciencedirect.com/science/article/pii/S1808869424000661, https://c19p.org/taheri2

6. Vaisi et al., The association between nutrients and occurrence of COVID-19 outcomes in the population of Western Iran: A cohort study

3,955 patient vitamin A prophylaxis study: 17% lower hospitalization (p=0.04) and 11% fewer symptomatic cases (p=0.03).
Analysis of nutrient intake and COVID-19 outcomes for 3,996 people in Iran, showing lower risk of COVID-19 hospitalization with sufficient vitamin A, vitamin C, and selenium intake, with statistical significance for vitamin A and selenium.
May 2023, The Clinical Respiratory J., https://onlinelibrary.wiley.com/doi/10.1111/crj.13632, https://c19p.org/vaisi

7. Nimer et al., The impact of vitamin and mineral supplements usage prior to COVID-19 infection on disease severity and hospitalization

2,148 patient vitamin A prophylaxis study: 21% lower hospitalization (p=0.4) and 21% lower severe cases (p=0.36).
Retrospective 2,148 COVID-19 recovered patients in Jordan, showing no significant differences in the risk of severity and hospitalization with vitamin A prophylaxis.
Feb 2022, Bosnian J. Basic Medical Sciences, https://www.bjbms.org/ojs/index.php/bjbms/article/view/7009, https://c19p.org/nimera

8. Holt et al., Risk factors for developing COVID-19: a population-based longitudinal study (COVIDENCE UK)

15,227 patient vitamin A prophylaxis study: 56% fewer cases (p=0.41).
Prospective survey-based study with 15,227 people in the UK, showing lower risk of COVID-19 cases with vitamin A, vitamin D, zinc, selenium, probiotics, and inhaled corticosteroids; and higher risk with metformin and vitamin C. Statistical significance was not reached for any of these. Except for vitamin D, the results for treatments we follow were only adjusted for age, sex, duration of participation, and test frequency. NCT04330599. COVIDENCE UK.
Mar 2021, Thorax, https://thorax.bmj.com/content/early/2021/11/02/thoraxjnl-2021-217487, https://c19p.org/holta

9. Al-Sumiadai et al., Therapeutic effect of vitamin A on COVID-19 patients and its prophylactic effect on contacts

209 patient vitamin A prophylaxis study: 64% fewer cases (p<0.0001) and 32% faster recovery.
Treatment and prophylaxis studies of vitamin A in Iraq. The prophylaxis study contained 209 contacts of COVID-19 patients, 97 treated with vitamin A, showing significantly lower cases with treatment, and shorter duration of symptoms. The treatment study is listed separately [Al-Sumiadai].
Jan 2021, Systematic Reviews in Pharmacy, https://www.researchgate.net/publication/351637178_THERAPEUTIC_EFFECT_OF_VITAMIN_A_ON_COVID-19_PATIENTS_AND_ITS_PROPHYLACTIC_EFFECT_ON_CONTACTS, https://c19p.org/alsumiadaip

10. Doocy et al., Clinical progression and outcomes of patients hospitalized with COVID-19 in humanitarian settings: A prospective cohort study in South Sudan and Eastern Democratic Republic of the Congo

144 patient vitamin A late treatment study: 26% lower mortality (p=1).
Prospective study of 144 hospitalized COVID-19 patients in the DRC and South Sudan, showing no significant difference with vitamin A treatment in unadjusted results with only 8 patients receiving vitamin A.
Oct 2022, PLOS Global Public Health, https://journals.plos.org/plosone/article?id=10.1371/journal.pgph.0000924, https://c19p.org/doocyva

11. Al-Sumiadai et al., Therapeutic effect of Vitamin A on severe COVID-19 patients

140 patient vitamin A early treatment study: 86% lower mortality (p=0.002).
Retrospective 70 severe condition patients treated with vitamin A (200,000IU for two days), salbutamol, and budesonide, and 70 patients not treated with vitamin A, showing significantly lower mortality with the addition of vitamin A.
Dec 2020, EurAsian J. Biosciences-7350, http://ejobios.org/article/therapeutic-effect-of-vitamin-a-on-severe-covid-19-patients-8517, https://c19p.org/alsumiadai2

12. Al-Sumiadai et al., Therapeutic effect of vitamin A on COVID-19 patients and its prophylactic effect on contacts

100 patient vitamin A early treatment study: 67% lower progression (p=0.27) and 38% faster recovery.
Treatment and prophylaxis studies of vitamin A in Iraq. The treatment study contained 100 patients, 50 treated with 200,000IU vitamin A for two days, showing lower progression to severe disease, and shorter duration of symptoms. The prophylaxis study is listed separately [Al-Sumiadai].
Jan 2021, Systematic Reviews in Pharmacy, https://www.researchgate.net/publication/351637178_THERAPEUTIC_EFFECT_OF_VITAMIN_A_ON_COVID-19_PATIENTS_AND_ITS_PROPHYLACTIC_EFFECT_ON_CONTACTS, https://c19p.org/alsumiadai

13. Sarohan et al., Retinol Depletion in Severe COVID-19

27 patient vitamin A late treatment study: 282% higher mortality (p=0.001).
Retrospective 27 severe COVID-19 patients and 23 non-COVID-19 patients, showing significantly lower vitamin A levels in COVID-19 patients (0.37mg/L vs. 0.52 mg/L, p<0.001). 10 of 27 COVID-19 patients received vitamin A, with higher mortality. Group details are not provided but authors note that 8 of 10 had comorbidities.
Jan 2021, medRxiv, https://www.medrxiv.org/content/10.1101/2021.01.30.21250844v1, https://c19p.org/sarohan

14. Somi et al., Effect of vitamin A supplementation on the outcome severity of COVID-19 in hospitalized patients: A pilot randomized clinical trial

30 patient vitamin A late treatment RCT: 76% slower improvement (p=0.21) and 8% longer hospitalization (p=0.49).
RCT 30 hospitalized patients in Iran, showing no significant difference with vitamin A treatment. All patients received HCQ. 50,000 IU/day intramuscular vitamin A for up to 2 weeks.
Oct 2022, Nutrition and Health, http://journals.sagepub.com/doi/10.1177/02601060221129144, https://c19p.org/somi

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