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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: 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.

The increasing lifespan in developed countries results in age-associated chronic diseases. Biological aging is a complex process associated with accumulated cellular damage by environmental or genetic factors with increasing age. Aging results in marked changes in brain structure and function. Age-related neurodegenerative diseases and disorders (NDDs) represent an ever-growing socioeconomic challenge and lead to an overall reduction in quality of life around the world. Alzheimer’s disease (AD) and Parkinson’s disease (PD) are most common degenerative neurological disorders of the central nervous system (CNS) in aging process. The low levels of acetylcholine and dopamine are major neuropathological feature of NDDs in addition to oxidative stress, intracellular calcium ion imbalance, mitochondrial dysfunction, ubiquitin-proteasome system impairment and endoplasmic reticulum stress. Current treatments minimally influence these diseases and are ineffective in curing the multifunctional pathological mechanisms. Synthetic neuroprotective agents sometimes have negative reactions as an adverse effect in humans. Recently, numerous ethnobotanical studies have reported that herbal medicines for the treatment or prevention of NDDs are significantly better than synthetic drug treatment. Medicinal herbs have traditionally been used around the world for centuries. Radix Glycyrrhizae (RG) is the dried roots and rhizomes of Glycyrrhiza uralensis or G. glabra or G. inflata from the Leguminosae/Fabaceae family. It has been used for centuries in traditional medicine as a life enhancer, for the treatment of coughs and influenza, and for detoxification. Diverse chemical constituents from RG have reported including flavanones, chalcones, triterpenoid saponins, coumarines, and other glycosides. Among them, flavanone liquiritigenin (LG) and its precursor and isomer chalcone isoliquiritigenin (ILG) are the main bioactive constituents of RG. In the present review, we summarize evidence in the literature on the structure and phytochemical properties and pharmacological applications of LG and ILG in age-related diseases to establish new therapeutics to improve human health and lifespan.