Bioavailability of alpha-tocopherol fed with retinol and relative bioavailability of D-alpha-tocopherol or DL-alpha-tocopherol acetate

J Dairy Sci. 1997 Feb;80(2):393-9. doi: 10.3168/jds.S0022-0302(97)75949-6.

Abstract

Two experiments were conducted to examine the effects of the form of alpha-tocopherol or interactions of alpha-tocopherol with vitamin A on its bioavailability. In Experiment 1, Holstein steers were fed a diet that was low in vitamins A and E for 1 mo; then, steers were blocked by body weight (X = 97.5 kg) and assigned randomly to one of four oral treatments: 1) no added vitamins, 2) 442 mg of retinyl acetate, 3) 1342 mg of D-alpha-tocopherol, or 4) 442 mg of retinyl acetate and 1342 mg of D-alpha-tocopherol. Each treatment was given as a pulse dose. Blood was sampled over a 36-h period. Concentrations of plasma retinyl palmitate peaked at 2 to 6 h postsupplementation for all calves and then peaked again at 22 to 28 h for calves receiving vitamin supplements. Concentrations of plasma alpha-tocopherol peaked earliest with D-alpha-tocopherol supplementation alone at 12 to 20 h after supplementation, but simultaneous supplementation with retinyl acetate resulted in lower plasma alpha-tocopherol concentrations. Plasma retinyl palmitate decreased during peak alpha-tocopherol concentrations. In Experiment 2, blood and tissue were analyzed after a single gastric tube administration of a powder (DL-alpha-tocopheryl acetate) or a liquid (D-alpha-tocopherol) form of vitamin E to Holstein calves. Plasma and kidney concentrations of alpha-tocopherol were higher when calves were fed D-alpha-tocopherol than when calves were fed the DL-alpha-tocopherol acetate form. Concentrations in the liver, spleen, adipose tissue, heart, muscle, cellular blood fraction, and gut did not differ between the two forms.

MeSH terms

  • Animals
  • Biological Availability
  • Cattle / metabolism*
  • Diet
  • Diterpenes
  • Kidney / metabolism
  • Kinetics
  • Male
  • Retinyl Esters
  • Tocopherols
  • Vitamin A / administration & dosage*
  • Vitamin A / analogs & derivatives
  • Vitamin A / blood
  • Vitamin E / administration & dosage*
  • Vitamin E / analogs & derivatives*
  • Vitamin E / blood
  • Vitamin E / pharmacokinetics*
  • alpha-Tocopherol* / analogs & derivatives*

Substances

  • Diterpenes
  • Retinyl Esters
  • Vitamin A
  • Vitamin E
  • retinol palmitate
  • alpha-Tocopherol
  • Tocopherols