Glutamate Supplementation in Young Men

Amino acids play an important role in human metabolism. In aging individuals and in some diseases, certain amino acids, such as glutamate, are at lower than normal levels. Glutamate appears to be involved in providing energy and maintaining normal blood sugar (glucose) levels, processes which both depend heavily on skeletal muscle. The maintenance of healthy blood sugar levels, in particular, is tightly related to overall muscle mass and quality. To better understand the link between glutamate and glucose metabolism in skeletal muscle, the investigators will be using a nutritional approach to raise the body's glutamate levels with monosodium glutamate (MSG) supplementation, and raise blood glucose levels with a sugary drink. By altering the normal levels of glutamate and glucose in the blood and muscle tissue, the investigators can gather more information about the role of glutamate in energy metabolism. This will help the design of future studies investigating the function of glutamate in aging and disease. During this study the investigators will increase the levels of glutamate and glucose in the bloodstream by asking participants to ingest MSG along with a sugary drink. The goal is to subsequently determine: A) the amount of glutamate and glucose that ends up in the muscle; and B) whether normal skeletal muscle glucose metabolism, and the behaviour of additional amino acids (other than glutamate) is altered. The hypothesis is that when MSG and sugar drink are ingested together glucose uptake and metabolism within the skeletal muscle will be elevated.