Primer on Dietary Carbohydrates and Utility of the Glycemic Index in Equine Nutrition

The feeding of “low carbohydrate” or “low glycemic” diets has been recommended for management of horses with metabolic and endocrine disorders in which insulin resistance is a component. A “low carbohydrate” diet is a misnomer, however, because horses require that a significant proportion of their daily ration comprises structural carbohydrates (fiber/forage) to maintain gut health and mental wellbeing. This article provides a detailed description of the different carbohydrates in equine feeds. It also reviews the terminology used to describe glucose and insulin responses to the ingestion of carbohydrates, in particular the concept of the glycemic index. Some of the factors that influence glycemic index in humans and the glycemic response to a meal in horses are also discussed.