Association of serum vitamin C with all-cause and cause-specific death: Data from National Health and Nutrition Examination Survey (NHANES 2003-2006).

OBJECTIVES: The association between levels of circulating vitamin C and mortality remains controversial. The aim of this study was to explore the non-linear association between serum vitamin C levels and all-cause or cause-specific mortality. METHODS: We included 9902 US adults with their serum vitamin C levels from the National Health and Nutrition Examination Survey (NHANES 2003-2006). Their survival information was retrieved from baseline until 2015 using the national death index. Multivariable Cox proportional hazards models were used to show the risk for all-cause or cause-specific death according to baseline serum vitamin C levels. Smooth curve fitting and threshold effect analyses were used to clarify potential nonlinearity. RESULTS: During a median follow-up of 10.6 y, there were 1558 all-cause deaths, including 320 from cancer, 374 from cardiovascular disease (CVD), and 120 from respiratory diseases. Serum vitamin C levels had a U-shaped relationship with all-cause or CVD-associated mortality. Interestingly, serum vitamin C levels lower than the threshold value (1.06 mg/dL) were negatively associated with all-cause (fully adjusted hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.59-0.86) and CVD (fully adjusted HR, 0.70; 95% CI, 0.47-1.03) mortality. In contrast, serum vitamin C levels higher than the threshold value (1.06 mg/dL) were positively associated with all-cause (fully adjusted HR, 1.33; 95% CI, 1.15-1.54) and CVD (fully adjusted HR, 1.60, 95% CI, 1.23-2.10) mortality, respectively. CONCLUSION: Serum vitamin C levels showed a U-shaped relationship with all-cause and CVD-associated deaths among US adults using the NHANES data.

Characterization of a protein-bound polysaccharide from Herba Epimedii and its metabolic mechanism in chronic fatigue syndrome.

OBJECTIVES: Herba Epimedii is one of the famous Traditional Chinese Medicines used to treat the chronic fatigue syndrome (CFS). The polysaccharides are the main active components in H. epimedii. The aim of this study is to discover the therapeutic effect and metabolic mechanism of H. epimedii polysaccharides against CFS. METHODS: The polysaccharide conjugates named HEP2-a were isolated from the leaves of H. epimedii using a water extraction method, and the general physicochemical properties of HEP2-a were analysed. In addition, a CFS rat model was established, and then, urinary metabonomic studies were performed using gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) in combination with multivariate statistical analysis. RESULTS: The physicochemical properties revealed that HEP2-a had an average molecular weight of 13.6×104Da and consisted of mannose (4.41%), rhamnose (5.43%), glucose (31.26%), galactose (27.07%), arabinose (23.43%), and galacturonic acid (8.40%). The amino acids in HEP2-a include glutamate, cysteine, leucine, tyrosine, lysine, and histidine. Molecular morphology studies revealed many highly curled spherical particles with diameters of 5-10µm in solids and 100-200nm for particles in water. Five metabolites in the HEP2-a group were oppositely and significantly changed compared to the CFS model group. CONCLUSION: Two metabolic pathways were identified as significant metabolic pathways involved with HEP2-a. The therapeutic effects of HEP2-a on CFS were partially due to the restoration of these disturbed pathways.

Metabolic mechanism of a polysaccharide from Schisandra chinensis to relieve chronic fatigue syndrome.

Schisandra chinensis fruits are a famous traditional Chinese medicine to treat all kinds of fatigue. This study aimed to investigate the therapeutic effect and metabolic mechanism of a polysaccharide (SCP) from Schisandra chinensis fruits on chronic fatigue syndrome (CFS). SCP was isolated and the physicochemical properties were analyzed. A CFS model of rats was established and the urinary metabonomic studies were performed using gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) in combination with multivariate statistical analysis. The results showed that SCP is a protein-bound polysaccharide. The amino acid composition of SCP consisted of 12 amino acids. The growth and the behaviors of the rats in the CFS model group were worse than those in the control group and improved after SCP treatment. Analysis of the GC-TOF-MS revealed that twelve metabolites were significantly changed, and six metabolites were oppositely and significantly changed after the SCP treatment. The TCA cycle metabolic pathways and the alanine, aspartate and glutamate metabolism were identified as significant metabolic pathways involved with SCP. The therapeutic mechanism of SCP against CFS was partially due to the restoration of these disturbed pathways.