alpha-Tocopherol Stereoisomers in Human Plasma Are Affected by the Level and Form of the Vitamin E Supplement Used

卷:145

Zhao, Yang ; Monahan, Frank J. ; McNulty, Breige A. ; Brennan, Lorraine ; Gibney, Mike J. ; Gibney, Eileen R.

关键词: vitamin E supplement intake;    RDA;    RRR-alpha-tocopherol;    all-rac-alpha-tocopherol;    bioactivity;    plasma alpha-tocopherol stereoisomers;    ROC analysis;   

DOI  :  10.3945/jn.115.213280

学科分类：食品科学和技术

【 摘 要 】

Background: Studies examining vitamin E intake and the percentage of the population meeting dietary guidelines do not distinguish between natural (RRR-alpha-tocopherol) and synthetic (all-rac-alpha-tocopherol) intake, even though these different isomeric forms differ in bioactivity. Objective: This study aimed to determine the effect of RRR-alpha-tocopherol vs. all-rac-alpha-tocopherol intake on the percentage of the population meeting the vitamin E recommendation and on plasma alpha-tocopherol stereoisomer distribution. Methods: With the use of data from the Irish National Adult Nutrition Survey (NANS), this study examined the percentage of the Irish population meeting the European Union (EU) RDA for vitamin E of 12 mg/d, correcting for a bioactivity difference in all-rac- vs. RRR-alpha-tocopherol, where 1 mg of all-rac-alpha-tocopherol is considered to be equivalent to 1:1.36 (0.74) mg in the EU RDA. In a subcohort of supplement users and nonusers, plasma alpha- and gamma-tocopherol concentrations and alpha-tocopherol stereoisomer distribution were measured. Receiver operating characteristic (ROC) curve analysis was conducted to determine ability to discriminate supplement user types. Results: Analysis of the NANS showed that 100% of participants still met the recommended intake of 12 mg/d, after allrac-a-tocopherol intake was corrected for alpha-tocopherol equivalent bioactivity. In the subcohort analysis, the percentage of plasma RRR-alpha-tocopherol was significantly lower in high all-rac-alpha-tocopherol supplement (>11 mg/d) users (82%) compared with nonusers and with high RRR-alpha-tocopherol supplement (>35 mg/d) users (91% and 93% respectively, P < 0.01). High RRR-alpha-tocopherol supplement users had a significantly higher plasma a-tocopherol than low all-rac-alpha-tocopherol supplement (<2.5 mg/d) users (34 vs. 25 mu mol/L, P = 0.01). ROC analysis demonstrated an ability to distinguish between RRR- and all-rac-alpha-tocopherol consumers, which may be useful in investigating the potential effect of RRR- and all-rac-alpha-tocopherol intake on health. Conclusions: This study demonstrated that the percentage of the population meeting the vitamin E recommendation was unaffected when all-rac-alpha-tocopherol intake was corrected for alpha-tocopherol equivalent bioactivity. all-rac-alpha-Tocopherol intake led to a decrease in the percentage of plasma RRR-alpha-tocopherol relative to RRR-alpha-tocopherol intake.