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Equine veterinary journal2025; doi: 10.1002/evj.70135

Leucine, pyridoxine and resveratrol supplementation alter metabolic parameters in ponies with equine metabolic syndrome.

Abstract: Supplements claiming to improve metabolic profiles in equine metabolic syndrome (EMS) often lack scientific validation. Objective: To evaluate the effect of a supplement containing leucine, resveratrol and pyridoxine on the metabolic profile in ponies with EMS. Methods: Unmasked randomised, placebo-controlled field trial. Methods: Thirty-eight ponies completed the trial across five farms. Ponies were age and sex matched per farm and randomly assigned to the supplement (n = 20) or placebo group (n = 18) with owners masked to group assignments. Ponies were sampled at days -1/0 (T1), 7/8 (T2), 30/31 (T3) and 60/61 (T4). Measurements included morphometrics, insulin, triglycerides, nonesterified fatty acids, leptin and adiponectin, a two-step insulin tolerance test and oral sugar test (OST). Biochemical and dynamic testing results were compared across groups and times using pairwise comparisons of the estimated marginal means from mixed model, with significance set at a Tukey corrected p-value of <0.05. Chi analyses assessed group differences from the trial onset and conclusion, with significance set at a p-value of <0.05. Results: In the supplement group, maximum insulin post-OST was significantly reduced between T1/T2 and T3/T4, and bodyweight (bwt) decreased significantly between T1 and T4. By T4, more ponies in the supplement group lost ≥2% of their bwt (p = 0.006), with an average reduction of 8.1 kg (95% CI: -11.4, -4.7) while the placebo group gained an average of 2.6 kg (95% CI: -4.2, 9.4). Additionally, more ponies in the supplement group reduced maximum insulin post-OST by ≥40% (p = 0.01 average decrease 36.6 μU/mL; 95% CI: -60.8, -12.3), compared with the placebo group (average decrease of 3.5 μU/mL; 95% CI: -24.8, 17.8). Conclusions: Small sample size across multiple farms may have increased variability and masked some effects. Conclusions: Supplementation with leucine, pyridoxine and resveratrol may support weight loss and reduce post-prandial insulin concentrations in ponies with EMS.
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Publication Date: 2025-12-08 PubMed ID: 41358782DOI: 10.1002/evj.70135Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study tested whether a supplement containing leucine, pyridoxine (vitamin B6), and resveratrol can improve metabolic health in ponies diagnosed with equine metabolic syndrome (EMS), a condition linked to obesity and insulin resistance.
  • The researchers conducted a randomized controlled trial and found that ponies receiving the supplement showed reduced body weight and lower insulin levels after eating compared to ponies given a placebo.

Background and Objective

  • Equine metabolic syndrome (EMS) is characterized by obesity, insulin resistance, and increased risk of laminitis (a painful hoof condition).
  • Various supplements claim to improve metabolic health in EMS ponies but often lack scientific evidence supporting their effectiveness.
  • This study aimed to rigorously evaluate the effects of a supplement containing leucine (an amino acid), pyridoxine (vitamin B6), and resveratrol (an antioxidant compound) on metabolic parameters in ponies with EMS.

Methods

  • The trial was an unmasked randomized placebo-controlled field study conducted on five farms with a total of 38 ponies completing the trial.
  • Ponies were matched by age and sex within each farm and randomly assigned to either the supplement group (20 ponies) or placebo group (18 ponies).
  • Owners were blinded to treatment assignments to minimize bias.
  • Sampling occurred at four time points: baseline (day -1/0, T1), after one week (day 7/8, T2), after one month (day 30/31, T3), and after two months (day 60/61, T4).
  • At each time point, researchers measured:
    • Body morphometrics (weight and body condition)
    • Blood levels of insulin, triglycerides, nonesterified fatty acids, leptin, and adiponectin (hormones related to metabolism and fat regulation)
    • Dynamic tests including a two-step insulin tolerance test and an oral sugar test (OST) to assess insulin sensitivity and secretion.
  • Data analysis used mixed models with pairwise comparisons adjusted for multiple testing (Tukey correction), and chi-squared tests to assess group differences over time.

Key Results

  • Ponies receiving the supplement showed:
    • A significant reduction in maximum insulin concentration after the oral sugar test, particularly notable between baseline and week 1 (T1 to T2) and between one month and two months (T3 to T4).
    • A significant decrease in bodyweight from baseline to two months (T1 to T4).
    • At two months, a larger proportion of supplement-fed ponies lost at least 2% of their body weight compared to placebo ponies (statistically significant with p = 0.006).
    • The average weight loss in the supplement group was about 8.1 kg, whereas the placebo group on average gained weight (~2.6 kg).
    • More ponies in the supplement group achieved a ≥40% reduction in maximum insulin post-OST, indicating improved insulin response (p = 0.01).
  • The placebo group showed very little change in weight or insulin levels.
  • No significant differences were reported for other metabolic hormones or fatty acids.

Interpretation and Conclusions

  • The findings suggest that supplementation with leucine, pyridoxine, and resveratrol can support weight loss and improve insulin regulation after meals in ponies with EMS.
  • Reducing post-prandial (after meal) insulin spikes is important in managing EMS because high insulin can increase the risk of laminitis and other complications.
  • The study helps provide scientific validation for a supplement often marketed to improve metabolic health in EMS-affected equids.
  • Limitations included:
    • A relatively small sample size spread across multiple farms, which may have introduced variability and obscured some potential effects.
    • The trial was unmasked (except for owner blinding), which could introduce some bias.
  • Further larger-scale studies could help confirm and expand upon these results.

Significance for Equine Health Management

  • Managing EMS mainly involves dietary control and exercise; this study identifies a potential supplemental strategy to aid weight loss and improve insulin dynamics.
  • Supplementing with leucine, pyridoxine, and resveratrol could be a promising adjunct therapy to help reduce EMS-associated risks, especially in ponies that are difficult to manage by diet alone.
  • Veterinarians and equine managers should consider scientific evidence when choosing supplements for metabolic disease management.

Cite This Article

APA
Norton EM, Plumb S, Shane D, Smalley L, McKendry K, Scharf B, Zemel M. (2025). Leucine, pyridoxine and resveratrol supplementation alter metabolic parameters in ponies with equine metabolic syndrome. Equine Vet J. https://doi.org/10.1002/evj.70135

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Norton, Elaine M
  • Department of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA.
Plumb, Sydney
  • Department of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA.
Shane, Douglas
  • Cornerstone Animal Health, Denton, Texas, USA.
Smalley, Lowell
  • Smalley Equine Veterinary Consulting, LLC, Omaha, Nebraska, USA.
McKendry, Kent
  • John Ewing Company, LaSalle, Colorado, USA.
Scharf, Bob
  • John Ewing Company, LaSalle, Colorado, USA.
Zemel, Michael
  • NuSirt Biopharma, Knoxville, Tennessee, USA.

Grant Funding

  • John Ewing Company

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