Vet World   Vol.19   January-2026  Article - 25 

Dietary 5-aminolevulinic acid modulates gut microbiota, reduces oxidative stress, and enhances immune status in weanling piglets: An 8-week exploratory study

Background and Aim: Five-aminolevulinic acid (5-ALA), a precursor in heme biosynthesis, has gained attention as a functional feed additive due to its reported benefits on metabolism, redox balance, and immunity. Although supplementation in sows and broilers has demonstrated favorable physiological outcomes, its effects on the gut microbiota and immune–oxidative profiles of weanling piglets remain unclear. This study aimed to evaluate whether 5-ALA supplementation modifies fecal microbiota composition and influences oxidative stress and immune parameters in piglets during the post-weaning period.

Materials and Methods: Twelve 28-day-old piglets were randomly allocated to a control or 5-ALA group (20 mg/kg feed) for 56 days. Body weight (BW), fecal samples, and blood samples were collected at 28, 56, and 84 days of age. Fecal microbiota was characterized by 16S rRNA sequencing (QIIME2). Oxidative stress and inflammatory markers in leukocytes (superoxide radical, hypochlorite ion) were quantified using a dual chemiluminescence/fluorescence system. Plasma malondialdehyde (MDA) and immunoglobulin G (IgG) were measured to assess systemic oxidative damage and humoral immunity. Statistical analyses included Permutational Multivariate Analysis of Variance, LEfSe, and Spearman correlations.

Results: BW did not differ significantly between groups, although the 5-ALA group tended to be heavier at 56 days. β-diversity differed significantly between groups at 56 and 84 days. Six and eight bacterial genera were differentially abundant at 56 and 84 days, respectively; 5-ALA supplementation enriched short-chain fatty acids-associated genera such as Coprococcus, Prevotellaceae UCG-003, and Phascolarctobacterium. At 84 days, the 5-ALA group showed markedly lower leukocyte superoxide levels (~3.5-fold reduction; p < 0.05) and a tendency toward lower hypochlorite ion production. Plasma IgG concentration was approximately 1.5-fold higher in the 5-ALA group (p < 0.05). Multiple bacterial genera exhibited significant correlations with oxidative and immune markers.

Conclusion: Dietary supplementation with 5-ALA altered the fecal microbiota and improved oxidative and immune status in weanling piglets, suggesting functional modulation of the gut–immune axis. Although exploratory and based on a small cohort, the findings warrant further controlled studies to validate dose–response effects and elucidate mechanistic pathways.

Keywords: 5-aminolevulinic acid, antioxidant capacity, gut microbiota, immune response, piglets, oxidative stress, weaning stress, swine nutrition.

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How to cite this article: Ishikawa S., Kawasaki K., Yano K., Kazumura K., Tsukahara T., Taniguchi S., Miura H., Inoue R. 2026. Dietary 5-aminolevulinic acid modulates gut microbiota, reduces oxidative stress, and enhances immune status in weanling piglets: An 8-week exploratory study. Vet World, 2026;19(1):348-358.

Received: 30-07-2025   Accepted: 08-12-2025   Published online: 30-01-2026

Corresponding author: Ryo Inoue    E-mail: ryo.inoue@setsunan.ac.jp

DOI: 10.14202/vetworld.2026.348-358

Copyright: Ishikawa, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.