Posted: 2nd April 2026 | Back to news feed
Magnesium for Horses: Benefits, Deficiency Signs & Why It Matters
There has been increasing interest in magnesium for horses, often referred to as the “super mineral” due to its wide-ranging benefits. From supporting calm behaviour to aiding metabolic health, magnesium plays a crucial role in your horse’s overall wellbeing.
Before adding a magnesium supplement to your horse’s diet, it’s important to understand how this essential mineral works within the body and why it can make such a difference.
What Does Magnesium Do for Horses?
Magnesium is a vital mineral found throughout the horse’s body. Around 60% is stored in the bones, while approximately 30% is found in muscle tissue.
It plays a key role in several important functions, including:
- Supporting muscle contraction and relaxation
- Enhancing oxygen delivery to muscles
- Promoting strength, endurance, and recovery
- Activating enzymes involved in energy production
- Supporting the nervous system
Because of its involvement in both muscular and neurological function, magnesium is essential for performance horses as well as those in everyday work.
Magnesium Deficiency in Horses
Despite its importance, magnesium is often overlooked in equine nutrition. A magnesium deficiency in horses can present in a variety of ways, and in some cases, may go unnoticed.
Common signs of low magnesium levels include:
- Nervousness or excitability
- Spookiness or sensitivity
- Muscle tremors or tightness
- Poor tolerance to exercise
- Difficulty relaxing
Spring grass can be particularly low in magnesium due to rapid growth, meaning horses grazing lush pasture may actually be at higher risk of deficiency. This is often when behavioural changes become more noticeable.
Why Magnesium Helps Calm Horses
Magnesium is widely used as a calming supplement for horses, but its effects are based on science rather than sedation.
Here’s how it works:
- Calcium is responsible for muscle contraction
- Magnesium controls muscle relaxation
When magnesium levels are low, muscles may struggle to fully relax, leading to tension, stiffness, and even spasms. At the same time, the nervous system becomes more sensitive, which can make horses reactive to noise, stress, and environmental changes.
This imbalance can trigger a cycle of stress and adrenaline release, resulting in the sharp or anxious behaviour often seen in magnesium-deficient horses.
Magnesium for Metabolic Health and Laminitis Risk
Magnesium for horses is also closely linked to metabolic health.
It may be particularly beneficial for horses that are:
- Overweight or prone to obesity
- At risk of laminitis
- Diagnosed with insulin resistance
- Affected by Equine Metabolic Syndrome (EMS)
Magnesium plays a role in how the body processes sugar and starch. After feeding, magnesium levels in the blood increase, indicating its involvement in insulin function and glucose regulation.
Low magnesium levels can lead to:
- Poor carbohydrate metabolism
- Reduced insulin sensitivity
- Increased risk of metabolic issues
Ensuring adequate magnesium intake can therefore help support a healthier metabolic response, particularly during high-risk periods such as spring grazing.
How Much Magnesium Does a Horse Need?
Magnesium is naturally present in forage and feed, and the horse’s body regulates it efficiently under normal conditions.
However, supplementation may be beneficial when requirements increase or dietary intake is insufficient.
As a general guideline:
- A 600kg horse in light to moderate work requires approximately 7.8g of magnesium for horses per day to maintain healthy levels
- Individual needs may vary depending on workload, diet, and overall health.
Choosing the Right Magnesium Supplement for Horses
When selecting a magnesium supplement for horses, it’s important to consider both quality and bioavailability.
- A high-quality supplement should:
- Provide sufficient daily magnesium levels
- Include highly absorbable forms such as magnesium chelate
- Support the nervous system with additional nutrients like B vitamins
Synovium MGNIUM – Advanced Magnesium Support for Horses
Synovium MGNIUM is a premium supplement designed to support your horse’s daily magnesium requirements and overall wellbeing.
Key features include:
- 9,000mg of magnesium per daily dose
- A combination of magnesium chelate and magnesium oxide for optimal absorption
- High levels of Vitamin B1 and Vitamin B6 (3,000mg each) to support the nervous system
- Designed to promote calm behaviour, muscle function, and stress support
This makes it an ideal choice for horses that are sensitive, in work, or requiring additional metabolic support.
Final Thoughts on Magnesium for Horses
Magnesium truly earns its reputation as a “super mineral.” From supporting calm behaviour and muscle function to aiding metabolic health, it plays a vital role in keeping your horse healthy and performing at their best.
If your horse is showing signs of tension, excitability, or struggling during seasonal changes, reviewing their magnesium intake could make a significant difference.
Check out Synovium’s Mgnium Supplement HERE.
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