Vitamin K: history, metabolism, and nutrition in the horse

Vitamin K (VK) has long been known for its essential role in blood coagulation. However, over the past decade, evidence has mounted for its intrinsic and essential roles in other functions within the body, including bone metabolism, calci fi cation, brain development and glucose metabolism. Thus, VK should no longer be considered a single-function ‘ haemostasis vitamin ’ , but rather as a ‘ multi-function vitamin ’ . While current research has focused on its emerging role in human nutrition, the role that VK plays in other species such as the horse has not been well described, with most of our current understanding having been extrapolated from other species, especially rodents. This review assesses the current state o f knowledge of VK as it pertains to human and animal nutrition, and, where data exist, its metabolism and nutrition in the horse is explored. Future research on the roles of VK as they pertain to horses, particularly extra-hepatic functions, is necessary. Such insight will allow a greater understanding of how VK is metabolised