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Metabolic syndrome increases dietary α-tocopherol requirements as assessed using urinary and plasma vitamin E catabolites: a double-blind, crossover clinical trial.
Traber, MG, Mah, E, Leonard, SW, Bobe, G, Bruno, RS
The American journal of clinical nutrition. 2017;(3):571-579
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Abstract
Background: Vitamin E supplementation improves liver histology in patients with nonalcoholic steatohepatitis, which is a manifestation of the metabolic syndrome (MetS). We reported previously that α-tocopherol bioavailability in healthy adults is higher than in those with MetS, thereby suggesting that the latter group has increased requirements.Objective: We hypothesized that α-tocopherol catabolites α-carboxyethyl hydroxychromanol (α-CEHC) and α-carboxymethylbutyl hydroxychromanol (α-CMBHC) are useful biomarkers of α-tocopherol status.Design: Adults (healthy or with MetS; n = 10/group) completed a double-blind, crossover clinical trial with four 72-h interventions during which they co-ingested 15 mg hexadeuterium-labeled RRR-α-tocopherol (d6-α-T) with nonfat, reduced-fat, whole, or soy milk. During each intervention, we measured α-CEHC and α-CMBHC excretions in three 8-h urine collections (0-24 h) and plasma α-tocopherol, α-CEHC, and α-CMBHC concentrations at various times ≤72 h.Results: During the first 24 h, participants with MetS compared with healthy adults excreted 41% less α-CEHC (all values are least-squares means ± SEMs: 0.6 ± 0.1 compared with 1.0 ± 0.1 μmol/g creatinine, respectively; P = 0.002), 63% less hexadeuterium-labeled (d6)-α-CEHC (0.04 ± 0.02 compared with 0.13 ± 0.02 μmol/g creatinine, respectively; P = 0.002), and 58% less d6-α-CMBHC (0.017 ± 0.004 compared with 0.041 ± 0.004 μmol/g creatinine, respectively; P = 0.0009) and had 52% lower plasma d6-α-CEHC areas under the concentration curves [area under the curve from 0 to 24 h (AUC0-24h): 27.7 ± 7.9 compared with 58.4 ± 7.9 nmol/L × h, respectively; P = 0.01]. d6-α-CEHC peaked before d6-α-T in 77 of 80 paired plasma concentration curves. Urinary d6-α-CEHC 24-h concentrations were associated with the plasma AUC0-24 h of d6-α-T (r = 0.53, P = 0.02) and d6-α-CEHC (r = 0.72, P = 0.0003), and with urinary d6-α-CMBHC (r = 0.88, P < 0.0001), and inversely with the plasma inflammation biomarkers C-reactive protein (r = -0.70, P = 0.0006), interleukin-10 (r = -0.59, P = 0.007), and interleukin-6 (r = -0.54, P = 0.01).Conclusion: Urinary α-CEHC and α-CMBHC are useful biomarkers to noninvasively assess α-tocopherol adequacy, especially in populations with MetS-associated hepatic dysfunction that likely impairs α-tocopherol trafficking. This trial was registered at clinicaltrials.gov as NCT01787591.
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α-Tocopherol supplementation reduces biomarkers of oxidative stress in children with Down syndrome: a randomized controlled trial.
Mustafa Nachvak, S, Reza Neyestani, T, Ali Mahboob, S, Sabour, S, Ali Keshawarz, S, Speakman, JR
European journal of clinical nutrition. 2014;(10):1119-23
Abstract
BACKGROUND Down syndrome (DS) is the most common human chromosomal abnormality. It is characterized by mental retardation and several metabolic disturbances, including elevated oxidative stress, which may be causally linked. Treatment with dietary antioxidants has been suggested as a potential method to alleviate the oxidative damage and retardation of DS patients, but prior supplementation work has been equivocal. AIM: To evaluate the effects of supplementation with antioxidants α-tocopherol and α-lipoic acid (ALA) on oxidative stress biomarkers in DS children. METHODS Ninety-three DS children aged 7-15 years from both sexes were randomly allocated to three groups: α-tocopherol (400 IU/day), ALA (100 mg/day) and placebo. The intervention period was 4 months. A healthy control group consisted 26 non-DS siblings. Serum thiobarbituric acid reactive substances (TBARS) and urinary 8-hydroxy-2'-deoxyguanosine (8OHdG) were used as biomarkers of oxidative stress. RESULTS DS children had greater levels of baseline oxidative stress than their siblings. Moreover, males had greater levels of 8OHdG than females (P<0.001) but there was no significant association between age and biomarkers of oxidative stress. Serum levels of TBARS did not change significantly over time, or relative to placebo. Although urinary 8OHdG concentrations decreased significantly in both α-tocopherol and ALA, groups compared with the baseline levels (P<0.001), mean final levels of urinary 8OHdG concentrations differed significantly only between α-tocopherol and placebo groups (P<0.01). CONCLUSIONS α-Tocopherol supplementation of the diets of DS children may attenuate oxidative stress at the DNA level.