Importance of Chromium in the Diet

The recognized function of chromium is as a component of glucose tolerance factor (GTF). GTF is thought to potentiate the action of insulin in chromium-deficient tissue. Insulin has anabolic characteristics as it promotes glucose uptake by the cell, stimulates amino acid synthesis, and inhibits tissue lipase.

Because of its role in carbohydrate, lipid, and protein metabolism and in the clearance of blood glucose, it is interesting to consider the requirements of the athletic horse for chromium. Chromium excretion is greater in athletic than in sedentary humans, and the chromium requirement is increased by physical activity. Research has shown that chromium supplementation can increase lean body mass in humans and pigs and results in a partitioning effect on nutrients that favors tissue anabolism and muscle protein accretion. In calves, chromium excretion is greater during stress, and chromium supplementation has resulted in a stimulation of the immune system and less mortality and morbidity in shipped feedlot cattle. Certainly this aspect of chromium is interesting when considering performance horses and the kind of stresses that they experience.

A study carried out at Kentucky Equine Research (KER) reported that supplementing performance horses with 5 mg/day of chromium in the form of chromium yeast had a beneficial effect on the response to exercise stress. Horses were subjected to a standard exercise test on a high-speed treadmill and blood and heart rate were monitored. The horses receiving chromium cleared blood glucose following a meal more quickly than control horses and showed lower peak insulin values and cortisol levels. Chromium-supplemented horses also had higher triglyceride values during exercise, possibly indicating more efficient fat mobilization. There was no difference in the heart rate in response to exercise between the two groups, but peak lactic acid concentrations in the chromium-supplemented group of horses were significantly lower than for the controls.

There is evidence that chromium supplementation has a positive impact on some horses known to have chronic problems with exertional rhabdomyolysis. In some types of tying-up, horses have a problem with normal glucose and glycogen metabolism. It may be that chromium assists in clearing glucose and makes glycogen utilization and storage more efficient.