Influence of sources of dietary vitamin E on the maternal transfer of α-tocopherol to fetal and neonatal guinea pigs as determined by a stable isotopic technique

• Published in: British journal of nutrition Vol. 89; no. 4; pp. 455 - 466
• Main Authors: Hidiroglou, N., Madere, R., McDowell, L. R., Toutain, P. L.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.04.2003
• Subjects: alpha-Tocopherol - metabolism; Animals; Animals, Inbred Strains; Animals, Newborn - metabolism; Bioavailability; Biological and medical sciences; Biological Availability; Dose-Response Relationship, Drug; Female; Fetus - metabolism; Fundamental and applied biological sciences. Psychology; Guinea pig; Guinea Pigs; Isotope Labeling; Lactation; Mammary Glands, Animal - metabolism; Maternal-Fetal Exchange; Mother. Fetoplacental unit. Mammary gland. Milk; Nutritional Status; Placenta - metabolism; Pregnancy; Pregnancy. Parturition. Lactation; Stable isotopes; Vertebrates: reproduction; Vitamin E - administration & dosage; Vitamin E - metabolism; Vitamin E sources; Vitamin E sources; Guinea pig; Bioavailability; Stable isotopes; Placental transfer; Rodentia; Vitamin; α-Tocopherol; Antioxidant; Fetomaternal relation; Feeding; Micronutrient; Pregnancy; Vertebrata; Mammalia; Diet; Newborn animal; Vitamin E sources: Bioavailability: Stable isotopes: Guinea pig; Isotopes
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1079/BJN2002788

The accepted biological potencies of vitamin E (United States Phamacopeia, 1985) for 1 mg all-rac-α-tocopheryl acetate (synthetic form) is 1·00 IU and that of 1 mg (RRR)-α-tocopheryl acetate (natural form) is 1·36 IU. In the present study, a stable isotopic (2H) technique was employed to evaluate the bioavailability of natural v. synthetic forms of vitamin E and to determine whether the potency of the forms is the stated relationship of 1·36:1·00 (RRR)-α-tocopheryl acetate:all-rac-α-tocopheryl acetate. Sixty female in-bred guinea pigs received either 40 or 80 mg vitamin E/kg diet with equal levels of (RRR)-α-tocopheryl acetate and all-rac-α-tocopheryl acetate throughout gestation and lactation. At late-term pregnancy (day 50 or 60) and during early lactation, dams and their corresponding fetuses or neonates were killed and various tissues collected for subsequent α-tocopherol analysis. Vitamin E analysis of fetal and neonatal tissues indicated a substantial transfer of 2H-labelled α-tocopherol across the placenta and through the mammary gland. Total α-tocopherol concentrations were significantly influenced by tissue type and dose level, but not by stage of gestation or lactation. The relative bioavailability (d3:d6) across fetal and neonatal tissues was on average 1·81:1·00, with a range from 1·62:1·00 to 2·01:1·00. Maternal tissues had a mean ratio of 1·77:1·00. A higher relative bioavailability (P≤0·05) was observed with natural compared with synthetic α-tocopherol as shown by a higher d3:d6 ratio in all tissues examined. Vitamin E was highest in colostrum on day 2 then declined through to day 5. Results from this present experiment further question the accepted biological potencies of natural:synthetic α-tocopheryl acetate of 1·36:1·00.