Vitamin B₆ supplementation increases immune responses in critically ill patients

Objective: To investigate whether vitamin B₆ supplementation has a beneficial effect on immune responses in critically ill patients. Design: A single-blind intervention study. Setting: The study was performed at the Taichung Veterans General Hospital, the central part of Taiwan. Subjects: Fifty-one subjects who stayed over 14 days in the intensive care unit completed the study. Subjects were not treated with any vitamin supplement before the intervention. Interventions: Patients were randomly assigned to one of three groups, control (n=20), a daily injection of 50mg vitamin B-6 (B₆-50, n=15), or 100mg vitamin B-6 (B₆-100, n=16) for 14 days.Main outcome measures:Plasma pyridoxal 5′-phosphate (PLP), pyridoxal (PL), 4-pyridoxic acid (4-PA), erythrocyte alanine (EALT-AC) and aspartate (EAST-AC) aminotransaminase activity coefficient, and urinary 4-PA were measured. The levels of serum albumin, hemoglobin, hematocrit, high-sensitivity C-reactive protein (hs-CRP) and immune responses (white blood cell, neutrophils, total lymphocytes count (TLC), T- (CD3) and B-(CD19) lymphocytes, T-helper (CD4) and suppressor (CD8) cells) were determined. Results: Plasma PLP, PL, 4-PA and urinary 4-PA concentrations significantly increased in two treated groups. T-lymphocyte and T-helper cell numbers and the percentage of T-suppressor cell significantly increased on day 14 in the B₆-50 group. Total lymphocyte count, T-helper and T-suppressor cell numbers, the percentage of T-lymphocyte cells and T-suppressors significantly increased in the B₆-100 group at the 14th day. There were no significant changes with respect to immune responses in the control group over 14 days. Conclusions: A large dose of vitamin B₆ supplementation (50 or 100mg/day) could compensate for the lack of responsiveness of plasma PLP to vitamin B₆ intake, and further increase immune response of critically ill patients.