Vitamin B2, also known as riboflavin, is essential for fatty acid oxidation because it is a precursor for the cofactors flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). These cofactors serve as electron carriers in the mitochondrial fatty acid β-oxidation pathway. Specifically, FAD is required for the activity of acyl-CoA dehydrogenase, the enzyme that catalyzes the initial step of fatty acid oxidation. Without adequate vitamin B2, this step is impaired, leading to deficient energy production from fatty acids. This makes vitamin B2 crucial for metabolic processes involving energy extraction from fats.

Reference: Harper's Illustrated Biochemistry, Rodwell, 31st Edition.