Alpha-tocopherol improves uptake and distribution of tocotrienol
Another study proves that alpha-tocopherol does not interfere with tocotrienol uptake and distribution
A recent study that evaluates the distribution of vitamin E isoforms (tocopherol and tocotrienol) in laying hens was conducted at Iowa State University, USA. The study shows that the presence of alpha-tocopherol improves the uptake and enhances the distribution of gamma- and delta-tocotrienols in certain tissues and organs.
It also demonstrates the poor uptake of annatto tocotrienol (tocopherol-free tocotrienol) as more than 90% of the tocotrienols are excreted.
The vitamin E family comprises eight chemically distinct compounds – four tocopherols and four tocotrienols (alpha, beta, gamma and delta, respectively). Alpha-tocopherol has been documented to be more bioavailable owing to its strong binding affinity to alpha-tocopherol transfer proteins (alpha-TTP) in the liver.
It was once thought that talpha-tocopherol exhibited biodiscrimination against other vitamin E forms, including tocotrienols. Hence, tocotrienols were mistakenly thought to be poorly absorbed in the presence of alpha-tocopherol.
In this tissue distribution study, an alpha-tocopherol and tocotrienol preparation showed higher gamma-tocotrienol levels in the liver, kidney and brain, whereas the distribution of delta-tocotrienol was higher in almost all the tissues tested (fat pad, liver, brain, oviduct, yolk, breast and thigh meat), compared with the tocopherol-free tocotrienol preparation (better known as Annatto Tocotrienol), suggesting that alpha-tocopherol facilitates the uptake and distribution of tocotrienols into tissues and organs.
In addition, the study reported that more than 90% of annatto gamma- and delta-tocotrienol intake was found in the faeces, indicating that less than 10% had been absorbed. This corresponds with the finding in humans wherein pharmacokinetic data showed that gamma- and delta-tocotrienol were poorly absorbed. The absolute absorption rate for gamma- and delta-tocotrienol is approximately 9.1% and 8.5%, respectively.
The results from this particular study complement two other earlier studies conducted at the Ohio State University Medical Center that showed tocotrienols are well-absorbed in alpha-TTP knock-out mice, and in a human tissue distribution study, where the tocotrienols are absorbed and deposited in vital human organs in the presence of alpha-tocopherol.
'This study caught our attention because the results are contradictory to the claim that alpha-tocopherol hinders the absorption of tocotrienol and one must take tocopherol-free tocotrienol to ensure tocotrienol is well-absorbed,' says Bryan See, Regional Product Manager, ExcelVite.
'As a fat-soluble compound, poor absorption and low bioavailability are the common issues for researchers and formulators. We can see from this study that more than 90% of annatto’s gamma- and delta-tocotrienols were found in the manure, indicating poor absorption. In fact, we reported the poor absorption and low bioavailability of tocotrienols in pharmacokinetic journals as early as 2000. Hence, we embarked on an extensive R&D programme to develop a patented food-grade Self-Emulsifying Delivery System (SEDS) for tocotrienols – called the SupraBio System. It has been shown in human clinical studies that EVNol SupraBio ensures a consistent delivery and improved absorption of each individual tocotrienol into the blood plasma by an average of 250%,' says CheeYen Lau, Nutritionist, ExcelVite Sdn Bhd.
'I am particularly proud of the fact that EVNol SupraBio has been selected and used in various human clinical studies, including a human tissue distribution study that conclusively proves that tocotrienols are delivered to and deposited at important tissues and organs even when alpha-tocopherol exists naturally in the formulation. It is the most bioavailable tocotrienol complex in the market with proven bioavailability and bioefficiency,' added Bryan See.
