Vitamin E status of Chinese population in Taiwan

Influence of apolipoprotein E genotype on fat-soluble plasma antioxidants in Spanish children

BACKGROUND

Apolipoprotein (apo) E is a major determinant of plasma lipid concentrations, which in turn influence the plasma concentrations of various fat-soluble vitamins.

OBJECTIVE

We aimed to analyze the effect of APOE genotype on fat-soluble antioxidant concentrations in children.

DESIGN

A total of 926 healthy boys and girls aged 6-8 y were selected from 4 cities in Spain. APOE genotyping was carried out, and plasma concentrations of lipids, apolipoproteins, and lipid-soluble antioxidants were measured.

RESULTS

Plasma lipid concentrations were strongly influenced by APOE genotype. The mean plasma concentration of alpha-tocopherol was 21.3 micromol/L, which is one of the highest values ever reported for a population of children. Although plasma concentrations of alpha-tocopherol, gamma-tocopherol, lycopene, and alpha-carotene varied significantly between subjects with different APOE genotypes, most of these differences disappeared after adjustment for lipoprotein-related covariates. Nevertheless, tocopherol concentrations remained elevated in individuals with the E2/2 genotype. Multivariate regression analysis showed interactions of APOE genotype with triacylglycerol and apo B in determining alpha-tocopherol concentrations. When subjects were stratified according to major apo E groups, apo B appeared to be the most important predictor of alpha-tocopherol concentrations in all groups, whereas triacylglycerol was identified only in carriers of the E2 allele.

CONCLUSIONS

The association between APOE genotype and lipophilic antioxidant concentrations is dependent mainly on the effect of the polymorphism on lipoprotein concentrations. However, triacylglycerol plays a role in determining the variability of alpha-tocopherol concentrations in E2 carriers only. This suggests that the alpha-tocopherol content in each lipoprotein class varies according to APOE genotype.

Plasma levels of antioxidant vitamins, selenium, total sulfhydryl groups and oxidative products in ischemic-stroke patients as compared to matched controls in Taiwan

The possible involvement of oxidative damage and antioxidant protection has been suggested in the pathogenesis of stroke which is the second-leading cause of death in Taiwan. In this study we investigated the relationship between ischemic stroke and plasma status of antioxidants and oxidative products. Plasma levels of vitamin A, alpha-tocopherol, carotenoids, selenium (Se), total SH groups (T-SH), thiobarbituric acid-reactive substances (TBARS) and protein carbonyl, a marker of protein damage, were determined in ischemic-stroke patients (n = 36, blood sampled within 24 hrs after the clinical event) in comparison with 21 matched controls. The cholesterol-adjusted carotenoids and vitamin E were significantly lower (P < 0.05) in the plasma of ischemic-stroke patients than those of the controls. TBARS were higher (P < 0.05) in the patients than in the controls but Se, T-SH and protein carbonyls were not significantly different between the two groups. Separation of the patients into small-artery ischemic stroke (SAIS, n = 17) and large-artery ischemic stroke (LAIS, n = 19) groups revealed that both carotenoids/cholesterol and vitamin E/cholesterol ratios were significantly lower in both LAIS and SAIS groups than the controls (n = 21) while vitamin A/cholesterol was not different among the three groups. TBARS were only significantly higher in the LAIS group. The results demonstrated that, within 24 hrs after the clinical event, the acute-ischemic stroke patients had lowered levels of cholesterol-adjusted carotenoids and alpha-tocopherol but elevated levels of TBARS in the plasma as compared to the matched controls. It remains to be resolved as to whether enhanced lipid peroxidation is a cause or a result of lowered antioxidants in ischemic stroke.

The use of different lipids to express serum tocopherol: lipid ratios for the measurement of vitamin E status

Plasma tocopherol was measured in 85 alcoholic patients and 40 control subjects from a local factory. Cholesterol, triglycerides and phospholipids were measured individually and summed to give an estimate of total serum lipids. Plasma tocopherol concentrations of the alcoholics were significantly lower than those of the controls and showed wide variation from marked deficiency to the upper limit of the normal range. Using regression analysis, 1.11 mumol tocopherol/mmol total lipids were calculated as the threshold of deficiency equivalent to 0.8 mg tocopherol/g total lipid established by Horwitt et al. The sensitivity and specificity of other tocopherol:lipid ratios for identifying vitamin E deficiency was compared with the tocopherol:total lipid ratio. Thresholds of deficiency for the different tocopherol:lipid ratios were calculated. The tocopherol:cholesterol+triglyceride ratio was found to be almost as powerful in identifying vitamin E deficiency as the tocopherol:total lipid ratio (sensitivity 95%, specificity 99%). Of the tocopherol:individual lipid ratios, the tocopherol:cholesterol ratio gave the best results (sensitivity 86%, specificity 94%).