Role of Vitamin D in Fish Growth and Immune Response: A Meta-Analysis

Abstract

Vitamin D (VD) is a steroid hormone, of which vitamin D₃ [Cholecalciferol/ 25(OH)D₃] is the primary form found in fish. Fish mostly obtain this fat-soluble vitamin D3 from their diets, making it a common feed additive in aquaculture. This study performed a meta-analysis of published trials to determine the effects of Vitamin D3 on growth and immune response, providing a more reliable assessment of vitamin D effects across different fish species. A database was built from published literature regarding the addition of Vitamin D3 doses and their relation to the immune response and growth performance of fish. A literature search was carried out in Medline, Embase, Science Direct, Google Scholar, and The Scopus (up to 2024) for randomized controlled trials (RCTs) with studies selected based on criteria that included quantitative measures of growth and immunity. The recorded parameters were related to the immune response and Growth performance. The database contained a total of 65 data points from 41 studies that met the criteria. Effect sizes were calculated for the difference in the results of Vitamin D3 supplements and the control group. The pooled effect size was −0.024 (95% CI : −0.050, 0.003; 13 trials) of Vitamin D3 for Weight Gain,  0.026 (95% CI :-0.009, 0.060, 14 Trials) for SGR, -0.074 ((95% CI :- 0.113, - 0.035, 9 trials) for FCR , +3.41 (95% CI: 2.82 to 4.00, 10 trials) for Lysozyme activity and +14.17 ( 95% CI : 11.62 to 16.72, 10 trials) for SOD activity. We found that Vitamin D3 supplements significantly enhanced growth, immunity and disease survival of treated fish, regardless of the treatment duration, fish trophic level, and type of material used. Finally, we observed that studies need to improve the reporting of critical information about vitamin D₃ supplementation (e.g., source, dosage, formulation, and administration method), to enable better comparison across different experiments and enhance the repeatability of findings regarding its effects on fish growth and immune response.