A team of researchers from the Duke Sarah W. Stedman Nutrition and Metabolism Center, including scientists from the departments  of medicine, pharmacology and cancer biology performed tests on human muscle cells that showed supplementing with Carnitine might help older people with prediabetes, diabetes, and other disorders that make glucose (sugar) metabolism difficult.

Carnitine is made in the liver and recycled by the kidney, but in some cases when this is insufficient, dietary Carnitine from red meat and other animal foods can compensate for the shortfall.
 
After just eight weeks of supplementation with Carnitine, laboratory subjects restored their cells’ fuel- burning capacity (which was shut down by a lack of natural carnitine) and improved their glucose tolerance, a health outcome that indicates a lower risk of diabetes. These results offer hope for a new therapeutic option for people with glucose intolerance, older people, people with kidney disease, and those with type 2 diabetes (also known as adult-onset diabetes).
 
The study is published in the Aug. 21 issue of the Journal of  Biological Chemistry.
 
The Duke researchers began studying Carnitine more closely when abnormalities in the nutrient emerged from blood chemistry profiles of obese and old subjects. These chemical profiles report on hundreds of by-products of cell metabolism called metabolites and give scientists an opportunity to identify markers of disease states.

Carnitine is a natural compound known for helping fatty acids enter the mitochondria, the powerhouses of cells, where fatty acids are “burned” to give cells energy for their various tasks. Carnitine also helps move excess fuel from cells into the circulating blood, which then redistributes this energy source to needier organs or to the kidneys for removal. These processes occur through the formation  of acylcarnitine molecules, energy molecules that can cross membrane barriers that encase all cells.
 
Researchers at Duke had observed that skeletal muscle of obese subjects produced high amounts of the acylcarnitines, which requires free Carnitine. As these molecules started to accumulate, the availability of free, unprocessed Carnitine decreased. This imbalance was linked to fuel-burning problems, that is, impairments n the cells’ combustion of both fat and glucose fuel.

“We suspected that persistent increases in acylcarnitines in the laboratory subjects were causing problems, and we could also see that the aavailability of free Carnitine was decreasing with weight gain and aging, It appeared that carnitine could no longer do its job when chronic metabolic disruptions were stressing the system. That’s when we designed an experiment to add extra Carnitine to the diet.”
 
The work was supported by grants from the National Institutes  of Health, and the American Diabetes Association, and a  John A. Hartford Duke Center for Excellence Award.