(P11-009-23) Egg-Mediated Bioavailability of Plant-Derived Vitamin E in Humans: A Pilot Study

Objectives: Long-standing dogma indicates that co-ingestion of fat is critical for fat-soluble vitamin E (α-tocopherol; α-T) absorption but recent evidence shows that dietary fat ingested several hours after α-T is sufficient to achieve bioavailability. Because lipid-containing foods, such as eggs, are expected to promote α-T bioavailability, we hypothesized that either concurrent or late ingestion of eggs would facilitate bioavailability of spinach-derived α-T in humans.

Methods: Spinach was grown hydroponically with 30% deuterium oxide prior to harvesting twice at 6- and 10-weeks post-germination. Harvested leaves were washed, chopped, cooked, portioned, vacuum-sealed, and stored at -20°C until consumed. HPLC-ECD and LC-MS analyses were performed to quantify nutrient concentration and isotopomer profile. In a 4-arm crossover pharmacokinetics pilot study, healthy adults ingested: 1) deuterium-labeled spinach (containing 5 mg α-T; SPIN); 2) spinach + 1 egg concurrently (SPIN+EGG_0h); 3) spinach + 1 egg 3h later (SPIN+EGG_3h); 4) spinach + 1 egg + 1 egg 3h later (SPIN+EGG_0h+EGG_3h) prior to timed blood collections over 72-h to assess bioavailability of deuterium-labeled α-T. Eucaloric diets controlled for α-T were provided for 3 days prior to and during the initial 24 h of each 72-h trial. Plasma deuterium-labeled α-T was analyzed by LC-MS.

Results: 100% of α-T in spinach was deuterium-labeled, with 78-83% of isotopomers between d₅ to d₁₁-α-T. Participants had adequate unlabeled (d₀-) α-T status (28.5 ± 1.6 μM). Pharmacokinetic profiling showed that deuterated α-T reached T_max at 12 h regardless of the timing of egg ingestion. A trend was observed for greater plasma deuterated α-T AUC_0-72h as well as maximal concentrations (C_max) in SPIN+EGG_0h and SPIN+EGG_0h+EGG_3h compared to SPIN and SPIN+EGG_3h groups.

Conclusions: These data demonstrate feasibility of deuterium-labeled spinach to examine food matrix effects and interactions in human bioavailability studies. Proof-of-concept findings suggest the potential effectiveness of concurrent ingestion, but not delayed ingestion of eggs, to promote α-T bioavailability, which will be confirmed in the actively underway large-scale clinical study.

Funding Sources: Egg Nutrition Center and OSU Center for Applied Plant Sciences