Many of the health benefits of vitamin E intake are believed to derive from its antioxidant properties( 1 ), among them the prevention of oxidation of PUFA( 2 ). Previous animal studies have demonstrated the importance of dietary vitamin E in protecting circulating PUFA( 3 , 4 ); however, to our knowledge this has not been investigated in humans.
This study aimed to determine the relationship between habitual vitamin E intake and plasma α-tocopherol concentrations on plasma fatty acid proportion, in a nationally representative sample. Dietary intake data from the National Adult Nutrition Survey (NANS)( 5 ) were used; valid reporters who did not consume supplements containing PUFA were included in the study (n = 601). Plasma α-tocopherol concentrations were measured by HPLC and plasma fatty acids were extracted and quantified using GC-MS. Participants were divided into vitamin E intake quartiles and plasma α-tocopherol quartiles and differences in plasma fatty acid proportion were explored by general linear regression using SPSS.
* general linear model univariate analysis, adjusted for gender, vitamin E containing supplement use, total energy and corresponding PUFA intake as percentage of total energy (%TE) intake, was carried out to determine significance with log transformed value; different superscript letters denote significant differences across vitamin E intake quartiles (P < 0·05)
Across both vitamin E intake and plasma α-tocopherol quartiles, PUFA intake significantly increased. Following adjustment for PUFA intake, vitamin E intake showed positive correlations with plasma n-3 PUFA (P < 0·001), EPA (P = 0·011) and DHA (P = 0·002) proportion and plasma n-3/n-6 ratio (P = 0·001) and a negative correlation with plasma eicosatrienoic acid (P = 0·023) proportion. When plasma α-tocopherol was examined, only plasma α-linolenic acid (ALA) proportion significantly increased with increasing plasma α-tocopherol (data not shown). These results suggest that circulating plasma n-3 PUFA (EPA and DHA) may be protected by vitamin E intake.
The work was jointly funded by the Department of Agriculture, Food and Marine under the Food for Health Research Initiative; Ms Zhao is in receipt of a PhD student from the China Scholarship Council 2011–2015.