Synthetic as compared with natural vitamin E is preferentially excreted as α‐CEHC in human urine: studies using deuterated α‐tocopheryl acetates

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Abstract
α-CEHC (2,5,7,8-tetramethyl-2(2′-carboxyethyl)-6-hydroxychroman) is a urinary vitamin E metabolite with a truncated phytyl tail. To test whether natural and synthetic vitamin E are similarly converted to α-CEHC, 6 humans consumed 150 mg each RRR-α-[5-(C2H3)]- and all rac-α-[5,7(C2H3)2]-tocopheryl acetates (d3 RRR-α- and d6 all rac-α-tocopheryl acetates, respectively). Plasma was collected at 0, 6, 12 and 24 h; urine (24 h) at 0, 1, 2, 3, 4 and 8 days. Following dosing, plasma was enriched with d3 RRR-α-tocopherol, while urine was enriched with α-CEHC derived from d6 all rac-α-tocopherol. Thus, synthetic compared with natural vitamin E is preferentially metabolized to α-CEHC and excreted.