Association of Polyunsaturated Fatty Acids and Vitamin B6 with Inflammation in Adults from the National Health and Nutrition Examination Survey (NHANES) 2003–2004

Abstract

Abstract Objectives Polyunsaturated fatty acids (PUFA) such as n-3 PUFA, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and n-6 PUFA, arachidonic acid (AA) may mediate inflammatory responses. Vitamin B6 deficiency has been shown to alter plasma PUFA levels. This perturbation of PUFA metabolism in vitamin B6 deficiency measured by pyridoxal-5’-phosphate (PLP) may contribute to inflammation. Thus, we aimed to examine the associations of 1) dietary EPA + DHA, and vitamin B6 with plasma ratio of AA/(EPA + DHA) by PLP level, 2) plasma AA/(EPA + DHA) and PLP with C-reactive protein (CRP), a marker for inflammation, and 3) dietary EPA + DHA, and vitamin B6 with CRP level, using NHANES. Methods NHANES datasets (2003–2004) with subjects ≥20 years were analyzed, accounting for survey design and sample weights (n = 4486). The significance level was P < 0.05. Covariates were age, gender, ethnicity, BMI, smoking, alcohol, total energy, dietary supplements, physical activity, and NSAIDs, depending on analyses. Multiple linear regression assessed the association of dietary EPA + DHA, and vitamin B6 with plasma ratio of AA/(EPA + DHA) by PLP level (Low: < 20 nmol/L, High: ≥20 nmol/L). Next, multivariate logistic regression predicted the associations of plasma AA/(EPA + DHA) and PLP with CRP level (Low: ≤3 mg/L, Moderate to High: > 3 mg/L); then, dietary EPA + DHA, and B6 with CRP level. Results In the low PLP level, dietary EPA + DHA was negatively associated with plasma ratio of AA/(EPA + DHA) (B = ─5.29, SE = 0.84, P = < .0001), but B6 intake was not, whereas, in the high PLP level, both dietary EPA + DHA (B = ─2.99, SE = 0.53, P = < .0001) and dietary vitamin B6 (B = ─0.21, SE = 0.04, P = 0.0001) were inversely associated with plasma AA/(EPA + DHA). Further, low PLP level was associated with greater odds of moderate to high CRP level compared to high PLP level (adjusted OR (aOR): 2.8, 95% CI: 1.93–4.04, P = < .0001), but plasma AA/(EPA + DHA) was not. In addition, both dietary EPA + DHA (aOR: 0.5, 95% CI: 0.23–0.98, P = 0.04) and vitamin B6 (aOR: 0.8, 95% CI: 0.68–0.95, P = 0.009) were inversely associated with moderate to high CRP level. Conclusions Our findings show that low plasma PLP level and low vitamin B6 intake are associated with inflammation, and the relationship may be through their effect on PUFA metabolism, suggesting that increased intake of vitamin B6 and EPA and DHA may protect against inflammation. Funding Sources N/A.