- Coat shedding and heavy exertion can increase the need for B vitamins
B vitamins are a group of water-soluble vitamins, each with its own function and chemical properties. Because they are water-soluble, B vitamins are not stored in the body but are excreted in urine if consumed in excess. Horses can produce some B vitamins in their gut with the help of bacteria. If gut function is impaired (e.g. diarrhea, intestinal inflammation, stress), the horse’s own B-vitamin production may be disrupted. In such cases, deficiencies must be compensated through the diet.
What are B vitamins needed for?
B vitamins are required for energy metabolism, protein synthesis, and the function of the nervous system and muscles. Competition horses and foals benefit the most from B-vitamin supplementation, as B vitamins support muscle energy production, nervous system function, and metabolism. Horses also benefit from B-vitamin supplementation during coat shedding, when hindgut production may be insufficient. Folic acid, a B vitamin, supports red blood cell formation and protein metabolism and is therefore especially important for horses under heavy workload.
Brewer’s yeast contains all essential B vitamins.
Who may benefit from B-vitamin supplementation?
There is limited research on the exact B-vitamin requirements of horses and how much is covered by endogenous production. Although deficiency signs are rare, the line between minimum requirements and optimal levels for performance may be unclear. Supplementation may be beneficial for horses on high-grain diets, under heavy stress or workload (competition, transport), those with poor appetite, diarrhea, poor condition due to illness, older horses with reduced digestive efficiency, horses with parasites, or very young horses with an undeveloped gut microbiota.
Supplementation has shown positive results particularly in heavily trained and competing horses that experience transport and competition stress. B vitamins appear to provide a natural “boost,” and while not all effects are scientifically proven, they are widely supported by experienced horse professionals.
Some B vitamins have been studied more extensively than others, with reported benefits in both academic research and practical field use.
Studies suggest that although thiamine (B1) is produced in large amounts in the hindgut, sufficient intake from the diet is still necessary. Thiamine is abundant in fresh green grass and brewer’s yeast. Traditionally, vitamin B1 has been used to calm nervous horses. While it does not work for all horses, evidence suggests a calming effect in horses showing undesirable behavior due to deficiency or increased requirement.
The horse’s gut microorganisms produce ample cobalamin (B12) when sufficient cobalt is present in the diet. B12 is not available from plants but is abundant in brewer’s yeast, which contains all B vitamins required by the horse. Brewer’s yeast is widely used to improve appetite, prevent anemia, and enhance performance, even though deficiency has not been documented. Unlike other B vitamins, horses can store vitamin B12 in their bodies.
Most B vitamins are obtained from fresh grass or high-quality forage, which should always form the foundation of a balanced diet. Horses in light to moderate work are likely to receive adequate B vitamins from their diet alone.
Feeding large amounts of B vitamins will not make a horse run faster or jump higher, but supplementation can sometimes help achieve optimal rather than minimal vitamin levels, thereby supporting peak performance.
