Natural Vitamin E Supplementation during Pregnancy in Rats Increases RRR-α-Tocopherol Stereoisomer Proportion and Enhances Fetal Antioxidant Capacity, Compared to Synthetic Vitamin E Administration

Introduction: Low dietary intake of vitamin E is a global public health issue. RRR-a-tocopherol (RRR-aT) is the only naturally occurring vitamin E stereoisomer, but the equimolecular mixture of all eight stereoisomers, synthetic vitamin E (S-aT), is commonly consumed. The objective of this study was to evaluate bioavailability and antioxidant activity of RRR-aT versus S-aT, in both mother and fetus, after maternal supplementation during pregnancy. Methods: Female rats (7 weeks of age) received a modified AIN-93G diet supplemented with 75 IU/kg of RRR-aT (NVE, n = 20) or S-aT (SVE, n = 17). At delivery, the levels of aT, stereoisomer distribution, and antioxidant capacity were analyzed in maternal and fetal plasma. Results: NVE administration significantly increased the proportion of RRR-aT stereoisomer in maternal and fetal plasma. The percentage of RRR-aT increased from 32.76% to 88.33% in maternal plasma, and 35.25% to 97.94% in fetal plasma, in the NVE group compared to SVE. Fetal plasma from the NVE group was found to have higher total antioxidant capacity compared to SVE. Lastly, fetal plasma RRR-aT stereoisomer percentage was positively associated with expression levels of scavenger receptor class B type 1 (SR-B1) in the placenta. Conclusions: Both natural and synthetic sources of vitamin E showed similar bioavailability. Still, NVE supplementation increased the proportion of RRR-aT and promoted higher antioxidant activity in fetal plasma at birth. Placental SR-B1 might be involved in the stereoselective transfer of RRR-aT stereoisomer across the placenta and may improve aT bioactivity in the fetus.

Automated summary

The objective of this study was to evaluate the bioavailability and antioxidant activity of RRR-aT compared to S-aT in both mother and fetus. The results showed that RRR-aT supplementation increased the proportion of RRR-aT in maternal and fetal plasma, resulting in higher antioxidant activity in fetal plasma. Placental SR-B1 may play a role in the stereoselective transfer of RRR-aT and enhance aT bioactivity in the fetus.