Docosahexaeoic acid (DHA) is the most abundant long chain polyunsaturated fatty acid in the grey matter of the brain. Although man has the capability of converting dietary linolenic acid into KHA, the evidence suggests that this process is slow. Consequently, at the time of most rapid brain development in the first few months of life, there is a critical demand for dietary DHA. Although DHA is provided to a nursing infant from mother's milk, most infant formulas are severely deficient in DHA. Attempts at supplementing infant formulas with fish oils have led to rejection due to the strong fishy odor and taste. Consequently, there is a need for an alternative DHA-containing oil as a nutritional supplement for infant formulations, and there is a need for further research on the uptake and metabolism of dietary DHA by both nursing mother and infant. Phytoplankton represent the largest depot of DHA on the Earth. The main goal of this research is to test the feasibility of using selected stains of DHA-producing microalgae for the production of an oil which can be used as a nutritional supplement for infant formulas and baby food. En route to this goal we will also develop the capability of producing 13C-labeled DHA; a nonradioactive research tool for the study of DHA uptake and metabolism using noninvasive nuclear magnetic resonance techniques.