Erythrocyte concentrations of B1, B2, B6 but not plasma C and E are reliable indicators of nutrition status in the presence of systemic inflammation.

Background & Aim: There is increasing evidence that the plasma concentration of vitamin D, carotenoids, zinc and selenium are associated with the magnitude of the systemic inflammatory response. In order to examine whether other vitamins may be affected and whether red cell concentrations are less affected by systemic inflammation the aim of the present study was to examine the effect of the systemic inflammatory response on red cell measurements of vitamins B1, B2 and B6, and plasma concentration of vitamin C and E in a large cohort of patients referred for a nutritional screen.

Methods: Patients referred for nutritional assessment of B1 (n = 551), B2 (n = 251), B6 (n = 313), ascorbic acid (n = 494) and α-tocopherol (n = 395) concentrations. These vitamins were measured using routine laboratory methods.

Results: The median concentrations of vitamin B1 grouped according to C-reactive protein concentrations ≤10, 11-80 and >80 mg/L were 543, 664 and 766 ng/g Hb respectively (p < 0.001, 41% higher). The median concentration of vitamin B1 grouped according to albumin concentrations ≥35, 25-34 and <25 g/l were 547, 664 and 701 ng/g Hb respectively (p < 0.001, 28% higher). The median concentrations of red cell vitamin B2 grouped according to CRP concentrations ≤10, 11-80 and >80 mg/L were 2.2, 2.3 and 2.4 nmol/g Hb respectively (p < 0.001, 9% higher). The median red cell concentrations of vitamin B2 grouped according to albumin concentrations ≥35, 25-34 and <25 g/l were 2.1, 2.4 and 2.3 nmol/g Hb respectively (p < 0.001, 14% higher). The median concentrations of red cell vitamin B6 grouped according to CRP concentrations ≤10, 11-80 and >80 mg/L were 534, 548 and 767 pmol/g Hb respectively (p < 0.001, 44% higher). The median red cell concentrations of vitamin B6 grouped according to albumin concentrations ≥35, 25-34 and <25 g/l were 462, 644 and 840 pmol/g Hb respectively (p < 0.001, 82% higher). In contrast, the median plasma concentrations of ascorbic acid grouped according to CRP concentrations ≤10, 11-80 and >80 mg/L were 25.0, 15.0 and 6.0 μmol/l respectively (78% lower, p < 0.001). The median plasma concentrations of ascorbic acid grouped according to albumin concentrations ≥35, 25-34 and <25 g/l were 32.0, 13.0 and 5.0 μmol/l respectively (84% lower, p < 0.001). The median α-tocopherol/cholesterol grouped according to CRP concentrations ≤10, 11-80 and >80 mg/L were 5.9, 4.6 and 2.1 μmol/l respectively (64% lower, p < 0.001). The median α-tocopherol/cholesterol grouped according to albumin concentrations ≥35, 25-34 and <25 g/l were 6.0, 5.5 and 2.1 μmol/l respectively (65% lower, p < 0.001).

Conclusion: Red cell concentrations of vitamins B1, B2 and B6 were not lower with an increasing systemic inflammatory response. In contrast, plasma concentrations of vitamin C and E were lower. Therefore, compared with plasma concentration, red cell concentrations of B1, B2 and B6 are likely to be more reliable measures of status in the presence of a systemic inflammatory response.