Research

The evidence behind Synaxis

This page sets out the research that informs the Synaxis formulation. We have written it plainly, including what the evidence supports and what it does not.

If you are considering an omega-3 nutritional supplement for your horse, we think you are better served by an honest account of the science than by a list of claims.

The evidence falls into three parts: the biochemical pathway, what changes in blood and tissue, and what changes in the horse. These answer different questions. We have kept them separate accordingly.

One distinction is worth stating upfront. The biochemical mechanism by which DHA and EPA influence inflammatory signalling is well-characterised — but primarily in human, rodent, and canine research. The clinical evidence in horses is more limited.

Where we cite equine studies, we cite them because they are the most methodologically robust references available, not because the field has reached consensus. We have been clear throughout about what each study shows and what it does not.

Why feeding linseed may not be doing what you think

Most omega-3 feeding in horses is based on linseed or linseed oil. These are rich sources of ALA — a short-chain omega-3 fatty acid found in plant material. The assumption behind feeding linseed is that the horse's body will convert ALA into EPA and DHA. The evidence suggests this assumption may not be reliable.

Converting ALA into EPA and DHA requires a series of enzymatic steps. Each step is rate-limited. The process also competes directly with omega-6 fatty acids for the same enzymes — and many UK horses eat diets that are high in omega-6.

A University of Florida study supplementing horses with ALA found no meaningful increase in DHA or EPA in blood or plasma. Where linseed does produce some increase in circulating EPA, DHA has typically remained unchanged. The conversion pathway can sometimes reach EPA, however inefficiently. DHA is harder still.

To put this in context: in humans — the closest available proxy for equine conversion rates — bioconversion of ALA to EPA is less than 10%, and to DHA less than 0.1%.

This does not mean linseed has no role in a horse's diet. It means that relying on it to deliver meaningful DHA is unlikely to work, regardless of how much is fed.

The constraint is in the pathway itself. Increasing the amount fed does not resolve it.

Synaxis Core provides EPA and DHA directly — from algae, the origin from which all marine omega-3 ultimately derives — in fixed, verified quantities, without reliance on conversion.

Vineyard KR, Warren LK, Kivipelto J. Effect of dietary omega-3 fatty acid source on plasma and red blood cell membrane composition and immune function in yearling horses. J Anim Sci. 2010;88(1):248–257.

The study that informed our dose

The primary published research informing the Synaxis Core formulation is a randomised, placebo-controlled clinical trial conducted at Purdue University College of Veterinary Medicine, published in the Journal of Veterinary Internal Medicine in 2015.

The study enrolled 35 client-owned horses diagnosed with chronic lower airway inflammatory disease. All horses received a low-dust diet — the established environmental management for airway disease. Half also received a daily algae-derived omega-3 supplement providing 1.5g DHA per day. The other half received a placebo. The intervention ran for eight weeks.

Because both groups received the low-dust diet, the differences in outcome between them are attributable to the supplement.

The question the trial answers is not whether environmental management helps — it does — but whether adding algae-derived DHA produces measurable improvements beyond that baseline. It did.

Findings in the supplemented group versus placebo:

Cough score improved by 60% versus 33%
Respiratory effort decreased by 48% versus 27%
Airway neutrophil percentage fell from 23% to 9% — in the placebo group, it rose from 11% to 17%
Plasma DHA increased more than tenfold

The supplement was algae-derived — the same source as Synaxis Core. Improvements were adjunctive to the low-dust diet, not independent of it.

In discussing their findings, the authors noted that the improvement in cough and respiratory effort was comparable in magnitude to improvements reported in a previous dexamethasone study. This was not a direct comparison, but it provides useful context for the scale of change observed during the trial.

What this study shows:
Algae-derived DHA is bioavailable in horses. It alters plasma phospholipid composition. It is associated with measurable changes in airway inflammatory markers. This provides the biological basis for the Synaxis Core dose.

What it does not show:
This trial studied horses with existing airway disease. It does not demonstrate that omega-3 supplementation alone manages equine airway disease, or that the same effects occur in healthy horses. We are not making that claim.

The evidence base in horses is still developing. We cite Nogradi because it is the most methodologically robust published reference currently available.

References
Nogradi N, Couetil LL, Messick J, Stochelski MA, Burgess JR. Omega-3 Fatty Acid Supplementation Provides an Additional Benefit to a Low-Dust Diet in the Management of Horses with Chronic Lower Airway Inflammatory Disease. J Vet Intern Med. 2015;29(1):299–306. doi:10.1111/jvim.12488

Read the full paper

Why dose and time both matter

The Nogradi trial found that 1.5g DHA per day was sufficient to alter plasma phospholipid composition and produce measurable clinical differences versus placebo. Doubling the dose produced no additional benefit. The requirement is not more — it is enough.

Many supplements on the market do not reach this threshold. This is where most fail.

But dose alone is not sufficient. DHA is incorporated into cell membranes — plasma phospholipids, joint fluid, respiratory tissue, skin. That process takes weeks, not days. Most studies, including Nogradi, observe meaningful changes over six to eight weeks. Effects in slower-turnover tissues take longer still.

Short-term supplementation can raise circulating levels without allowing meaningful tissue incorporation. That is why this is structured as a protocol rather than an open-ended supplement.

Why these amounts, and why this ratio

Synaxis Core delivers 3.1g DHA and 1.0g EPA per 10ml maintenance dose. Both exceed the threshold demonstrated to produce measurable biological changes in the Nogradi trial.

The formulation is DHA-dominant. This reflects the natural composition of Schizochytrium microalgae, and the consistent finding in equine research that DHA is the primary long-chain omega-3 that accumulates in plasma following supplementation.

The carrier oils, sunflower and MCT (derived from coconut oil), improve stability and contain no active ingredients.

What Synaxis Core is

Synaxis Core is a nutritional supplement providing direct EPA and DHA. It is not a veterinary medicine and is not intended to treat, cure, or prevent any condition.

The research on this page informs the formulation and dose rationale. It does not constitute a clinical claim for the product.

If your horse has a clinical condition, work with your vet. Synaxis Core is designed to sit alongside that conversation — not replace it.

Synaxis Core is formulated around this research — delivering EPA and DHA directly, at doses consistent with the Nogradi trial.

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Further reading:
Vineyard KR et al., 2010 — Plasma and red blood cell fatty acid composition in yearling horses
Nogradi N et al., 2015 — DHA supplementation in horses with airway inflammatory disease