Splanchnic uptake and metabolism contributes significantly to the differences in flux seen between the intravenous and intragastric ingestion of certain indispensable amino acids.

This is the third in a series of studies designed to increase the investigators knowledge of the metabolism of two indispensable amino acids, threonine and lysine, by the splanchnic bed. In the initial two studies the investigators established the neonatal parenteral requirement of threonine and lysine. In the current study, the investigators will be examining the differences in uptake and metabolism of threonine and lysine across the splanchnic bed.

We propose that we will see a smaller amount of enterally fed isotopes reach the plasma as compared to the amount in plasma from the parenterally delivered isotopes. We also believe that the amount of enterally delivered threonine isotope that reaches the plasma will be significantly less than the amount of enterally fed lysine isotope.

Inclusion Criteria:

• Healthy Males

Exclusion Criteria:

• History of inborn error of metabolism
• Presence of a chronic disease
• Have unusual dietary practices
• Has recently lost weight
• Receiving pharmacological therapy or hormonal treatment