Association of vitamin B-6 status with inflammation, oxidative stress, and chronic inflammatory conditions: the Boston Puerto Rican Health Study

Abstract

Background: Low vitamin B-6 status has been linked to an increased risk of cardiovascular diseases. The cardioprotective effects of vitamin B-6 independent of homocysteine suggest that additional mechanisms may be involved.

Objective: Our objective was to examine the cross-sectional association of vitamin B-6 status with markers of inflammation and oxidative stress.

Design: We measured plasma pyridoxal-5'-phosphate (PLP), C-reactive protein (CRP), and an oxidative DNA damage marker, urinary 8-hydroxydeoxyguanosine (8-OHdG), in Puerto Rican adults who were living in Massachusetts (n = 1205, aged 45-75 y).

Results: There was a strong dose-response relation of plasma PLP concentration with plasma CRP. Increasing quartiles of PLP were significantly associated with lower CRP concentrations (geometric means: 4.7, 3.6, 3.1, and 2.5 mg/L; P for trend < 0.0001) and with lower urinary 8-OHdG concentrations (geometric means: 124, 124, 117, and 108 ng/mg creatinine; P for trend: 0.025) after multivariate adjustment. These negative associations persisted after plasma homocysteine was controlled for. Plasma PLP concentrations were significantly correlated with plasma fasting glucose (r = -0.1, P = 0.0006), glycated hemoglobin (r = -0.08, P = 0.006), and homeostasis model assessment of beta cell function (r = 0.082, P = 0.005). Metabolic syndrome, obesity, and diabetes were also significantly associated with low plasma PLP concentrations (P = 0.011, 0.0007, and 0.004, respectively).

Conclusions: Low vitamin B-6 concentrations are associated with inflammation, higher oxidative stress, and metabolic conditions in older Puerto Rican adults. Our data suggest that vitamin B-6 may influence cardiovascular disease risk through mechanisms other than homocysteine and support the notion that nutritional status may influence the health disparities present in this population.

Figures

FIGURE 1

Geometric means (with 95% CIs) of plasma C-reactive protein (CRP) (A) and urinary 8-hydroxydeoxyguanosine (8OHdG) concentrations (B) by quartiles (Q) of plasma pyridoxal 5′-phosphate (PLP). P values for trend, in general linear models, were adjusted for age, sex, smoking status, alcohol intake, physical activity, hormone use among women, dietary vitamin B-6, folate intake, protein and total energy intake, and plasma homocysteine. *, **Significantly different from the lowest quartile: *P < 0.05, **P < 0.001.

FIGURE 2

Mean (±SE) association of plasma pyridoxal 5′-phosphate (PLP) concentration and chronic disease status. P values for mean differences between groups with and without a condition were adjusted for age, sex, smoking status, alcohol intake, physical activity, hormone use among women, dietary vitamin B-6, and folate, protein, and total energy intake in a general linear model. Black bars represent the percentage of vitamin B-6 inadequacy (PLP < 20 nmol/L). MetS, metabolic syndrome.