Supplementation with RRR- or all-rac-α-Tocopherol Differentially Affects the α-Tocopherol Stereoisomer Profile in the Milk and Plasma of Lactating Women

Abstract

Background: The naturally occurring α-tocopherol stereoisomer RRR-α-tocopherol is known to be more bioactive than synthetic α-tocopherol (all-rac-α-tocopherol). However, the influence of this difference on the α-tocopherol stereoisomer profile of human milk is not understood.Objective: We investigated whether supplemental RRR-α-tocopherol or all-rac-α-tocopherol differentially affected the distribution of α-tocopherol stereoisomers in milk and plasma from lactating women.Methods: Eighty-nine lactating women aged 19-40 y and with a body mass index (in kg/m²) ≤30 were randomly assigned at 4-6 wk postpartum to receive a daily supplement containing 45.5 mg all-rac-α-tocopherol acetate (ARAC), 22.8 mg all-rac-α-tocopherol acetate + 20.1 mg RRR-α-tocopherol (MIX), or 40.2 mg RRR-α-tocopherol (RRR). Milk and plasma were analyzed for α-tocopherol structural isomers and α-tocopherol stereoisomers at baseline and after 6 wk supplementation with the use of chiral HPLC.Results: There were no significant treatment group or time-dependent changes in milk or plasma α, γ, or δ-tocopherol. RRR-α-tocopherol was the most abundant stereoisomer in both milk and plasma in each group. Supplementation changed both milk and plasma percentage RRR-α-tocopherol (RRR > MIX > ARAC) (P < 0.05) and percentage non-RRR-α-tocopherol (ARAC > MIX > RRR) (P < 0.05). In the RRR group, percentage RRR-α-tocopherol increased in milk (mean ± SEM: 78% ± 2.3% compared with 82% ± 1.7%) (P < 0.05) and plasma (mean ± SEM: 77% ± 1.8% compared with 87% ± 1%) (P < 0.05). In contrast, the percentage RRR-α-tocopherol decreased in the MIX and ARAC groups (MIX, P < 0.05; ARAC, P < 0.0001), and percentage non-RRR-α-tocopherol stereoisomers increased (MIX, P < 0.05; ARAC, P < 0.0001) commensurate with an accumulation of 2S-α-tocopherol stereoisomers (P < 0.05) in both milk and plasma. Milk and plasma RRR-α-tocopherol was positively correlated at baseline (r = 0.67; P < 0.0001) and 6 wk (r = 0.80; P < 0.0001).Conclusion: The α-tocopherol supplementation strategy differentially affected the α-tocopherol milk and plasma stereoisomer profile in lactating women. RRR-α-tocopherol increased milk and plasma percentage RRR-α-tocopherol, whereas all-rac-α-tocopherol acetate reduced these percentages. Because RRR-α-tocopherol is the most bioactive stereoisomer, investigating the impact of supplement-driven changes in the milk α-tocopherol stereoisomer profile on the α-tocopherol status of breastfed infants is warranted.

Keywords: RRR-α-tocopherol; breast milk; lactation; maternal plasma; stereoisomer; α-tocopherol.