Intramitochondrial fatty acid metabolism: riboflavin deficiency and energy production

Abstract

Inborn errors of fatty acid β-oxidation have contributed significantly to our understanding of intracellular fatty acid metabolism. The first intramitochondrial step in β-oxidation of fatty acyl-CoA of different chain lengths is catalyzed by the three chain length specific acyl-CoA dehydrogenases. Inherited deficiency of these enzymes has been reported. Some are riboflavin responsive. The first step of fatty acid oxidation is reviewed with specific emphasis on β-oxidation in newborn infants, rendered riboflavin deficient by phototherapy. Given that medium chain fatty acids are not stored as triacylglycerols and undergo rapid β-oxidation, they have been proposed as superior substrates compared with long chain triglycerides in times of metabolic stress. This review also examines medium chain triglycerides as an alternate energy source. When medium chain triglycerides were fed as 50% of total energy, glucose sparing was present with little loss of energy as dicarboxylic acids.Key words: β-oxidation, acyl-CoA dehydrogenase, riboflavin, medium chain triglycerides, dicarboxylic acids.