New Insights into Tocotrienol Isomer Uptake in the Plasma and Tissues of Rats Supplemented with Tocotrienol-Rich Fraction Solubilized in Palm Kernel Olein Carrier.

INTRODUCTION/OBJECTIVE: Tocotrienol-rich fraction (TRF) possesses anti-cancer, anti-inflammatory, neuroprotective, cardio-protective properties; however, its biological activity is limited by lower bioavailability compared to alpha-tocopherol. Although TRF has been studied with longchain triglyceride (LCT)-based carriers such as palm olein (PO), the influence of medium-chain triglyceride (MCT)-rich carriers remains unclear. This study aimed to evaluate the safety and uptake of TRF solubilised in palm kernel olein (PKO) or palm olein (PO) carrier in rats. METHODS: Female Sprague-Dawley rats were orally supplemented with carrier alone, or TRF solubilised into the carrier, PKO+TRF and PO+TRF for 1 day (acute), 14 days (subacute), and 90 days (subchronic). Blood was collected for liver function tests and plasma vitamin E analysis. Tissue uptake was assessed in the lung, liver, heart, brain, spleen, and kidney. RESULTS: No significant toxicity was observed under the study conditions. PKO appeared to enhance TRF bioavailability in plasma and liver during a short-term (14-day) supplementation period. In contrast, PO was associated with increased plasma bioavailability during long-term supplementation (90 days). DISCUSSION: Vitamin E absorption and tissue distribution were strongly influenced by the fatty-acid composition of the carriers used. PKO (MCT-rich) enhanced the short-term absorption, whereas PO (LCT-rich) appeared to support sustained retention over time. CONCLUSION: PKO may be a novel carrier for enhancing short-term TRF absorption, while PO appears suitable for longer-term supplementation. These findings provide preliminary evidence of carrier- dependent differences in tocotrienol bioavailability.