Spirulina (Arthrospira platensis) is a microalga that has been used as a dietary supplement for decades. On the human side, it has been studied extensively, but in horses the research evidence has been considerably more limited. A new peer-reviewed study published in February 2026 brings new, measured data to this field.
The study examined how 30 days of spirulina supplementation affects horses' physiological responses after exercise. The horses received 30 grams of spirulina daily, after which biomarkers in their blood and synovial fluid were measured before and after a standardized exercise test.
The results were not dramatic, but they were biologically interesting.
Red Blood Cells and Oxygen Transport
One of the clearest findings related to blood parameters. In the horses receiving spirulina, red blood cell count and hemoglobin levels were slightly higher after exercise compared with the control group. The change was not huge, but it was measurable. Because red blood cells are responsible for transporting oxygen to tissues, this suggests that spirulina may influence oxygen transport capacity during or after exertion.
Another interesting finding involved the molecule resolvin D1 (RvD1). Resolvins are not compounds that initiate inflammation; rather, they are associated with the controlled resolution of the inflammatory response. When tissue is stressed, the body initiates an inflammatory response. Just as important as the initiation of that response is its timely shutdown. In the spirulina group, RvD1 levels increased, which suggests that spirulina may participate in this "resolution phase."
By contrast, no significant changes were seen in the activity of antioxidant enzymes such as SOD and GSH-Px, and no major differences were observed in biomarkers related to articular cartilage. This is an important point: in this study, spirulina did not act as a strong antioxidant booster, nor did it directly affect markers of joint tissue.
Spirulina as Support for Recovery From Exercise
Exercise causes controlled stress in the body: microdamage to muscle cells, oxidative stress, and activation of the inflammatory response. Adaptation occurs precisely through this stimulus. The key is not to prevent stress, but to ensure that the body can regulate the response efficiently and return to balance in order to avoid damage.
Spirulina did not appear to block the inflammatory response, but rather to be associated with its regulation. This is a more subtle, but biologically meaningful, difference. The body's ability to move from an active inflammatory phase into a controlled recovery phase is a central part of coping with exertion and recovering from it.
The possible effects of spirulina can also be considered through its composition. It contains abundant protein, minerals, and bioactive compounds such as phycocyanin, which has been studied in connection with oxidative stress and inflammatory responses. Spirulina is not a single active ingredient, but a complex nutritional whole in which multiple compounds act simultaneously.
In previous studies, spirulina has also been examined from the perspective of metabolic health, especially in horses with insulin resistance or metabolic syndrome. In those contexts, changes have been observed in inflammatory markers and metabolic parameters. The new study did not focus on metabolic health, but it adds to the picture of spirulina's possible role in the body's regulatory systems.
This was a relatively short, 30-day intervention combined with a moderately demanding exercise test. Spirulina did not radically change equine physiology. Its effect was subtle, but clearly measurable.
That is precisely what makes the study interesting. Spirulina does not appear as a "miracle substance," but rather as a nutritional factor that may influence the body's regulatory mechanisms — especially the rebalancing process after exertion.
In equine feeding, the greatest effects always come from the whole picture: the forage base, mineral balance, energy intake, and training program. Spirulina does not replace these. But in light of this study, it may be one of the factors that influences how the horse’s body responds to and recovers from exertion.
