Time for a Renaissance in Vitamin E Research
Vitamin E refers to a collection 4 naturally occurring tocopherol and 4 tocotrienol isomers. Its primary role in the body is to prevent lipid peroxidation by breaking the chain reaction generating free radicals. Because α-tocopherol has the highest biologic activity in the body, much of the research has focused on this form even though γ-tocopherol is the predominant dietary form. Based on insights in the metabolism of different vitamin E isomers, the Food and Nutrition Board, Institute of Medicine recommends that people consume 15mg α-tocopherol daily.
In her IUNS 20th International Congress of Nutrition presentation “Advances in Vitamin E Science: Research Trends and Perspectives in Benefits for Human Health”, 2013 DSM Nutritional Sciences Award recipient Professor Maret Traber of the Linus Pauling Institute emphasized the symbiotic relationship between polyunsaturated lipids and vitamin E. Dietary fat is necessary for vitamin E absorption. Vitamin E is needed to keep unsaturated lipids (fat) from being oxidized. Dr. Traber informed the audience that α-tocopherol remains in the plasma longer and is not excreted as rapidly as other isomers. Using epidemiological and animal research, she reported the importance of vitamin E during pregnancy.
Ley and colleagues investigated the effect of dietary vitamin E intake during the second trimester of pregnancy on insulin resistance and hyperglycemia later in pregnancy. 205 women, pregnant with only one child, were given 3h glucose-tolerance tests at 30 wk of gestation. The authors did not report plasma α-tocopherol concentrations. The average self-reported daily vitamin E intake among the women was 7.9 mg. Similar to data from What We Eat in America 2009-2010 where women 30-39y consume an average of 7.6 mg α-tocopherol daily, <50% of the recommended intake. Ley and associates report that higher vitamin E intakes are associated with lower fasting glucose, lower insulin resistance (measured by HOMA) and higher insulin sensitivity index.
Almost before the invention of the internet ;-), Paolisso and associates reported that pharmacologic vitamin E supplementation (900 mg/d for 4 mo) reduced indicators of oxidative stress and improved insulin sensitivity. Their study was conducted with 10 healthy subjects and 15 individuals with non-insulin dependent diabetes. Baseline plasma vitamin E levels were <3µmol/L. Vitamin E supplementation increased plasma α-tocopherol levels 333%, to ~8-10 µmol/L. These levels still fall well below 30 µmol/L which is the optimal concentration with regards to mortality (Wright et al, 2006).
For more than a decade, people have not been consuming the vitamin E RDA. Vitamin E has not been designated a ‘nutrient of concern’ because people are not dying from deficiency diseases; Just like people are not dying from vitamin D deficiency. However, evidence is emerging that suboptimal vitamin E status, like less than adequate vitamin D levels, may not support optimal health.
It is time for a renaissance in vitamin E research.
Ley SH, Hanley AJ, Sermer M, Zinman B, O’Connor DL. Lower vitamin E intake during the second trimester is associated with insulin resistance and hyperglycemia later in pregnancy. 2013 EJCN doi:10.1038/ejcn.2013.185
Paolisso G, D’Amore A, Giugliano D, Ceriello A, Varrichio M, D’Ononfrio F. Pharmacologic doses of vitamin E improve insulin action in healthy subjects and non-insulin-dependent diabetic subjects. 1993 AJCN 57:650-656
Wright ME, Lawson KA, Weinstein SJ, Pietinen P, Taylor PR, Virtamo J, Albanes D. Higher baseline serum concentrations of vitamin E are associated with lower total and cause-specific mortality in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. 2006 AJCN 84:1200-1207