Grant: Doctoral Research Award - PA: RPP - Newfoundland and Labrador

Amino acids are the building blocks of proteins but many also play critical roles in metabolism. For example, methionine is responsible for gene regulation and the synthesis of essential products such as cysteine, taurine, creatine and phosphatidylcholine. The synthesis of these products is critical in infants since breast milk and formula do not provide adequate amounts to a growing neonate. Methionine is an essential amino acid which means that all of the required methionine must come from the diet. Thus, a sufficient dietary intake of methionine is vital for normal metabolism and overall growth. However, the metabolism of methionine also results in the formation of homocysteine which is a risk factor for cardiovascular disease. Methionine can be regenerated from homocysteine provided the essential nutrients folate and betaine are available. Folate is deficient in most populations and little is known regarding betaine intake. Since methionine can be regenerated by folate and betaine, the dietary intake of these nutrients will impact the methionine requirement. If an infant diet meets the defined methionine requirement, but is deficient in folate and betaine, does the baby need more methionine? What is the total amount of methionine needed for synthesis of these essential products? How do folate and betaine supplements affect this nutrient demand? This proposal seeks answer these questions using isotope tracers and the neonatal pig as a model for the infant. The methionine requirement will be determined when folate and betaine are present as well as when they are removed from the diet. We will also measure the change in methionine regeneration from homocysteine in folate/betaine-deficient animals that are subsequently 'rescued' with either folate, betaine or both. Since the quality of neonatal nutrition has an impact on the development of obesity and disease into adulthood, we hope that through these experiments we can help explain this phenomenon.