“This is the first study to our knowledge to describe the impact of differing sources of supplemental alpha-tocopherol on the human milk alpha-tocopherol profile,” the researchers wrote in their report, published in The Journal of Nutrition.
While alpha-tocopherol derived from plant sources like dark green leafy vegetables, nuts, or seeds comprises only the single naturally occurring stereoisomer RRR-alpha-tocopherol, the researchers argued that most dietary supplements use synthetic alpha-tocopherol (known as all-rac-tocopherol), which comprise eight possible alpha-tocopherol stereoisomers.
The differences the researchers found in stereoisomer distribution in breast milk samples have a potential to affect how a baby’s nervous system develops, especially with 95% of US childbearing-aged-women not meeting the current Estimated Average Requirement of 12 mg alpha-tocopherol per day, according to NHANES data.
Study design
Researchers collected milk and blood samples from 89 US mothers between the ages of 19 to 40 with a BMI at and under 30. The study participants had delivered full-term singleton infants within four to six weeks of the study’s start, had been continuously lactating, and planned to continue breastfeeding for six weeks.
The participants were part of an umbrella study looking at lutein, DHA, and alpha-tocopherol supplementations.
For this particular study, participants were randomly assigned to one of three groups and were asked to consume two study capsules per day in the morning with food for six weeks. The possible supplements were 45.5 mg of all-rac-alpha-tocopherol, a mix of 22.8 mg all-rac-alpha-tocopherol and 20.1 mg RRR-alpha-tocopherol, or 40.2 mg of just RRR-alpha tocopherol.
Participants provided a sample of breast milk and blood before starting the supplementation period for baseline measurements, and then once again at the end of the six-week period.
Findings
Tocopherol source did not differentially affect the alpha-tocopherol of milk or plasma, but it did influence the alpha-tocopherol stereoisomer distribution in both milk and plasma.
“We consider [this] important because milk potentially serves as the sole source of alpha-tocopherol for developing infants,” the researchers said. “This might affect the alpha-tocopherol functional status in breastfed infants given the established differences in bioavailability of [different] stereoisomers.”
In this study, the researchers found that supplementation with only RRR-alpha-tocopherol decreased the percentage of non-RRR stereoisomers, whereas supplementation with all-rac-alpha-tocopherol increased the non-RRR-alpha-tocopherol stereoisomers in milk.
Limits of the exploratory study included the 10-day washout period potentially not long enough for an analysis of alpha-tocopherol. In addition, cholesterol and triglyceride levels were not measured, meaning participants with hyperlipidemia could not be identified.
“Hyperlipidemia reduces the uptake of newly absorbed alpha-tocopherol into plasma and results in a slow turnover,” the researchers wrote, but in sum, “these findings support the need for further research into the impact of the milk alpha-tocopherol stereoisomer profile on infant health and development.”
Source: The Journal of Nutrition
Published online ahead of print, doi: 10.3945/jn.116.245134
Authors: Shahank Gaur, et al.