Inflammation causes tissue-specific depletion of vitamin B6

Vitamin B6 deficiency results in adverse health consequences, including hyperhomocysteinemia [1] and possibly arteriosclerotic lesions [2]. We have reported that the degree of disease activity is associated with vitamin B6 indices in patients with rheumatoid arthritis [3,4]. Bates and colleagues reported suboptimal vitamin B6 status in inflammatory conditions and in the acute-phase response in the elderly population [5]. These observations have attracted attention partly because vitamin B6 deficiency and several markers of inflammation were both found to be independent risk factors for thrombosis [6,7]. Although several clinical trials and epidemiological studies have demonstrated the associations between vitamin B6 and inflammatory diseases, the association between vitamin B6 status and inflammatory markers has been contentious, and the cause-effect relationship between these two has not been elucidated.Pyridoxine deficiency increased the degree of paw edema by 54% in a rat model of inflammation; it was therefore suggested that pyridoxine deficiency might enhance inflammation [8]. However, in healthy middle-aged adults, B vitamin status does not seem to be a strong correlate of circulating levels of inflammatory markers [9]. In contrast, a low level of circulating vitamin B6 was found to be associated with elevation of the inflammatory marker C-reactive protein independently of plasma homocysteine levels in the Framingham Heart Study cohort [10]. A recent study indicated that low plasma concentrations of pyridoxal 5'-phosphate are inversely related to major markers of inflammation and independently associated with increased coronary artery disease in the Italian population [11]. Decreased vitamin B6 status was also reported in patients after surgery and trauma [12]. In conditions with inflammation such as inflammatory bowel disease, low plasma levels of vitamin B6 are commonly found, especially in patients with active disease [13]. In a recent study we observed str