Equine Metabolic Syndrome

Review: Nutritional Supplementation Options for Supporting Insulin Regulation in Horses

By Lindsay Korac for STRUCTURE Supplements

Introduction

Insulin dysregulation is a central feature of Equine Metabolic Syndrome and is one of the most clinically important endocrine abnormalities in horses because of its association with hyperinsulinemia-associated laminitis. In affected horses, tissues such as skeletal muscle and adipose tissue may become less responsive to insulin, requiring the pancreas to secrete greater amounts of insulin to maintain normal blood glucose concentrations. As a result, many horses with insulin dysregulation maintain normal glucose while having abnormally high insulin.

Management of insulin dysregulation should be viewed as a long-term metabolic management strategy rather than a short-term correction. The foundation remains low-sugar/low-starch feeding, body condition management, controlled pasture access, appropriate exercise when sound, and repeated blood monitoring. Nutritional supplementation may be used as an additional support strategy, but should be used in addition to proper dietary management or veterinary care. Most research understands the concept that before considering supplements, the most important dietary intervention is reducing non-structural carbohydrate intake, including sugars, starches, and fructans. High-NSC feeds can exaggerate insulin responses, especially in horses with insulin dysregulation. For this reason, horses with suspected or confirmed EMS are commonly managed with mature grass hay, hay testing, hay soaking when needed, restricted pasture access, and low-NSC ration balancers or feeds. Weight control is also critical. Adipose tissue is metabolically active and contributes to inflammatory and hormonal changes that may worsen insulin regulation. In overweight horses, gradual weight loss can improve insulin sensitivity. Exercise, when safe and appropriate, can also improve glucose uptake by skeletal muscle and reduce insulin demand.

Understanding Nutritional Supplements for Insulin Regulation in Horses

For horse owners managing Equine Metabolic Syndrome or insulin dysregulation, nutritional supplementation has become an increasingly important component of comprehensive metabolic health programs. While proper management practices such as maintaining an appropriate body condition, feeding a low-sugar and low-starch diet, managing pasture intake, and providing exercise when appropriate remain the foundation of successful management, targeted nutritional support can help complement these efforts and support long-term metabolic wellness.

Many nutritional ingredients have been investigated for their roles in supporting healthy insulin function, glucose metabolism, inflammatory balance, antioxidant protection, and muscle maintenance. Although the level of scientific evidence varies among individual ingredients, growing research suggests that nutritional supplementation may help support the body's natural metabolic processes and contribute to maintaining healthy insulin regulation when used alongside appropriate management practices.

Among the ingredients commonly found in equine metabolic supplements, omega-3 fatty acids have received increasing attention due to their role in supporting healthy inflammatory responses and overall metabolic health. Although omega-3s are not considered direct insulin-lowering agents, they may help support whole-body metabolic function and are often included in nutritional programs designed for horses with metabolic concerns. Antioxidants such as vitamin E are also commonly incorporated into metabolic support programs. These nutrients help protect cells from oxidative stress and are particularly important for horses with limited access to fresh pasture. While antioxidants do not directly treat insulin dysregulation, they can contribute to overall health and wellness, especially in aging horses or those with restricted diets. Chromium and magnesium are also discussed in the literature, both playing an important roles in normal metabolism and insulin signaling within the body. While some studies have suggested potential benefits, research results have been inconsistent, meaning they may be helpful for some horses but are not considered proven solutions for insulin dysregulation.

In recent years, the focus has shifted from viewing supplements solely as a means of addressing specific deficiencies to recognizing their broader role in supporting whole-body health. Ingredients such as omega fatty acids, antioxidants, vitamins, minerals, and muscle-support nutrients may help optimize cellular function, support healthy tissues involved in glucose utilization, and promote an internal environment that favors metabolic balance. Rather than serving as a replacement for sound management practices, nutritional supplementation is best viewed as an additional layer of support within a comprehensive metabolic health strategy.

Table 1: Current supplementation practices and research

Figure 1: Evidence scale.
5 = Strong, consistent research support. 4 = Good support. 3 = Moderate/supportive evidence. 2 = Limited or mixed evidence. 1 = Weak evidence

Table 2: Evidence scoring and definition for above chart

More recently, nutritional approaches have begun focusing on the importance of maintaining healthy muscle mass. Skeletal muscle is one of the primary tissues responsible for utilizing glucose in response to insulin. Products that support muscle maintenance through high-quality protein sources, amino acids, and other nutritional components may indirectly support metabolic health by helping maintain lean body mass. This is particularly relevant for senior horses, horses undergoing weight management programs, or those with reduced exercise levels. 

Many modern equine supplements combine several of these ingredients into multi-ingredient formulations designed to support metabolic health from multiple angles. These products often contain combinations of amino acids, omega-3 fatty acids, vitamins, minerals, and plant-derived compounds. While research in this area continues to grow, results are often specific to the individual formulation being studied. Consequently, it is important to evaluate each product based on its ingredients, scientific support, and measurable outcomes rather than assuming all metabolic supplements provide the same benefits.

STRUCTURE Muscle+

STRUCTURE Muscle+ was originally formulated to support muscle health, recovery, and overall wellness through a combination of high-quality oils, essential fatty acids, and antioxidants. Interestingly, many of the same nutritional pathways involved in muscle health are also important for metabolic function and insulin regulation.

Supporting the Body's Largest Glucose-Utilizing Tissue

Skeletal muscle is one of the primary tissues responsible for utilizing glucose in response to insulin. When insulin is released, muscle tissue absorbs glucose from the bloodstream and uses it for energy or stores it for future use. Maintaining healthy muscle tissue is therefore an important part of overall metabolic health. STRUCTURE Muscle+ provides a blend of essential fatty acids and nutrients that support normal muscle function and recovery. By helping horses maintain healthy, metabolically active muscle tissue, the body may be better equipped to utilize glucose efficiently and reduce the need for excessive insulin production.

The Role of Omega Fatty Acids -
The cranberry oil, wild-caught fish oil, and non-GMO soybean oil found in STRUCTURE Muscle+ provide a broad spectrum of omega-3, omega-6, and omega-9 fatty acids. These fatty acids play important roles in cell membrane structure, cellular signaling, and inflammatory balance throughout the body. Research in both animals and humans has shown that healthy cell membranes are essential for normal insulin signaling. When cells respond efficiently to insulin, less insulin is required to achieve the same metabolic effect. While omega fatty acids are not a direct treatment for insulin dysregulation, they contribute to the overall metabolic environment that supports healthy insulin function.

Antioxidant Protection and Metabolic Health -
STRUCTURE Muscle+ also contains natural vitamin E and antioxidant-rich cranberry oil. Antioxidants help protect cells from oxidative stress, which occurs naturally during metabolism, exercise, aging, and inflammatory processes. Oxidative stress has been associated with metabolic dysfunction in many species. By supporting the body's antioxidant defenses, vitamin E and naturally occurring tocopherols may help maintain healthy cellular function and support tissues involved in energy metabolism.

A Highly Digestible Energy Source:
Unlike feeds that derive energy primarily from sugars and starches, oils provide concentrated calories without causing substantial increases in blood glucose. This allows horses to obtain energy from dietary fat rather than relying solely on rapidly digestible carbohydrates. For horses requiring additional calories, replacing a portion of dietary energy with healthy fat sources may help support a more balanced metabolic profile compared with higher-starch feeding programs.

Why Might Lower Insulin Levels Be Observed?

When improvements in insulin concentrations are observed over time, it is likely that multiple factors are contributing. Proper dietary management, body condition control, exercise, veterinary care, and nutritional supplementation often work together to support metabolic health.

The ingredients found in STRUCTURE Muscle+ may contribute to this process by:

• Supporting healthy muscle mass and function
• Providing essential fatty acids involved in cellular signaling
• Supporting normal inflammatory balance
• Providing antioxidant protection
• Supplying calories from fat rather than rapidly digestible carbohydrates
• Supporting overall metabolic health and energy utilization

Because skeletal muscle is one of the body's largest consumers of glucose, nutritional strategies that support healthy muscle tissue and efficient energy metabolism may help the body maintain more normal insulin responses over time.

The Bottom Line

STRUCTURE Muscle+ was developed to support whole-body wellness through targeted nutritional support for muscle health, recovery, and metabolic function. While no supplement alone can replace proper management practices, the combination of omega fatty acids, antioxidant vitamin E, and highly digestible fat sources provides nutritional building blocks that support healthy cellular function, muscle maintenance, and energy metabolism.

Figure 2: Mean blood insulin levels in Spike when supplemented with Structure Muscle vs without supplementation (pmol/L).

We wanted to evaluate the impact of STRUCTURE Muscle+ as part of a horse's nutritional management program. Spike, a 20-year-old Quarter Horse gelding, underwent blood testing in October 2025, which revealed a resting insulin concentration of ~840 pmol/L, a level consistent with significant hyperinsulinemia and insulin dysregulation. Following the introduction of STRUCTURE Muscle+ into his daily feeding program, repeat blood testing demonstrated substantially lower insulin concentrations down to 231 pmol/L. Over the six-month monitoring period, Spike maintained a markedly improved insulin profile compared to his October baseline while maintaining his management routine with no reported changes to feed or exercise level. While individual case observations cannot establish cause and effect, these results suggest that nutritional support, when incorporated into a comprehensive management program, may help support healthy metabolic function and long-term wellness in horses.