Serum Metabolomic Response to Long-Term Supplementation with all-rac - α -Tocopheryl Acetate in a Randomized Controlled Trial.
Level 2 - randomized trial
Nested randomized controlled trial sub-study
PubMed 27840740 · doi:10.1155/2016/6158436
What was done
Metabolomic profiling was performed on baseline and follow-up fasting serum from 200 men randomly selected from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study (50 participants from each of four arms: 50 mg/day all-rac-α-tocopheryl acetate [ATA], 20 mg/day β-carotene, both, or placebo). Changes in serum metabolite profiles were compared between participants receiving vitamin E and those who were not.
What was found
After correction for multiple comparisons, ATA supplementation resulted in statistically significant alterations in five metabolites (change in metabolite level expressed as standard deviations on the log scale, β): - α-CEHC sulfate increased (β = 1.51, p = 1.45 × 10⁻³⁸) - α-CEHC glucuronide increased (β = 1.41, p = 1.02 × 10⁻³¹) - α-tocopherol increased (β = 0.97, p = 2.22 × 10⁻¹³) - γ-tocopherol decreased (β = -0.90, p = 1.76 × 10⁻¹¹) - β-tocopherol decreased (β = -0.73, p = 9.40 × 10⁻⁸) Glutarylcarnitine, beta-alanine, ornithine, and N6-acetyllysine also decreased (β range 0.40 to -0.36), but not statistically significantly.
Why it matters
These results demonstrate that long-term synthetic α-tocopherol supplementation sharply depletes circulating γ- and β-tocopherol while elevating α-tocopherol metabolites. Understanding these specific biochemical alterations helps clarify why clinical cancer prevention outcomes have varied across major vitamin E supplementation trials.
Limits
The analysis was conducted in a sub-sample of 200 male participants from a trial of male smokers, limiting direct generalizability to non-smokers and women. The study evaluated circulating metabolic biomarkers rather than direct clinical cancer endpoints.