Friday Research Review: Vitamin B6 supplementation improves rheumatoid arthritis symptoms

Vitamin B6 supplementation improves pro-inflammatory responses in patients with rheumatoid arthritis.

Original Research Article

Authors: Huang, S.C., Wei, JC-C, and Huang (2010); Y-C. European J. of Clinic. Nutr.

Review: Ali Al-Rajhi, MPH

Huang et al. (2010) investigated if there were benefits of B6 supplementation on inflammatory and immune responses with rheumatoid arthritis (RA) patients. The study design was a single-blind co-intervention at a Taiwanese hospital. The control group (n=15) were given 5 mg/day of folic acid while the experimental group (n=20) were given 5 mg/day of folic acid and 100mg/day of vitamin B6. Over a 12 week period measurements were taken of plasma PLP, serum folate, inflammatory parameters (e.g., hs-CRP, ESR, IL-6, TNF-a), and immune parameters (e.g., white blood cell, total lymphocyte, T-cell, B-cell, T-helper cell, T-suppressor). Overall, researchers found that patients with RA, supplementation with 100 mg/day doses of B6 “suppressed pro-inflammatory cytokines (IL-6 and TNF-a).”

The first strength I noticed was an aspect of the research methodology; researchers took the effort to stay in constant  contact with all their participants through  weekly reminders to take their tablets and have them log their diet (via 24 diet recall at week 0 and 12) before their clinical visit. I believe the small study population made it feasible to stay in consistent contact and it ensured higher compliance. Also, researchers eliminated the interference of folate metabolism by methotrexate (usually taken to treat RA) by co-intervening folic acid into the study.

There were weaknesses in the study as well. The obvious was the low study population. The p-values for all of the measures were either not significant or approaching a trend, expect for plasma interleukin-6. Another limitation were the inclusion of patients taking methotrexate; this should be more of an exclusion factor. Also, I believe the population samples was likely to be homogeneous (Taiwanese), which cannot be generalizable to other poulations and there were far fewer men then women that participated (2 of 15 in control and 3 of 17 in experimental). The limitations that the researchers indicated include the loss of eight patients may have “decreased the degree of effect of plasma PLP on inflammatory and immune response,” that the study was a “single-blind rather than a double-blind study,” and “the short disease duration of our patients.”

There is potential for future research to strength the potential claims this paper found. First, increasing the study population to a number that is found in similar research that contain similar population characteristics. Second, establishing more stringent exclusion factors such as not allowing patients traking methotrexate. Lastly, establishing a double-blind study versus the single-blind design that was chosen for the study.