Table 2.

¹H NMR metabolomics studies in OA using NMR spectroscopy, undertaken on urine samples

Authors	Clinical, experimental or spontaneous OA	Animal type	Study groups	Number of samples	Proton Frequency	Total number of metabolites identified	Differentially abundant metabolites	Prospective metabolic pathways/biological context with respect to OA
Lamers et al, 200324	Spontaneous	Guinea pig	Osteoarthritic and healthy guinea pigs treated with variable vitamin C doses	44,randomly separated between different treatment groups	400 MHz	Not mentioned	Lactic acid, malic acid, hypoxanthine and alanine	Energy production and purine metabolism
Lamers et al, 200525	Clinical	Human	Non-OA controls and 45 individuals with radiographic OA of the knees or hips	92, 47 in non-OA group and 45 OA	600 MHz	Not mentioned	Hydroxybutyrate, pyruvate, creatine/creatinine, glycerol,histidine and methylhistidine.	Altered energy utilization, articular chondrocyte changes.