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

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.

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.

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).

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.

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.