Bioavailability of tocotrienols: evidence in human studies

Area of Science:

• Nutritional Science
• Biochemistry
• Pharmacology

Background:

• Tocotrienols, a minor component of vitamin E, possess unique biological activities including neuroprotection, radio-protection, anti-cancer, anti-inflammatory, and lipid-lowering properties.
• Unlike tocopherols, tocotrienols' therapeutic window and bioavailability mechanisms require further elucidation for human applications.
• Understanding tocotrienol absorption is crucial before extensive clinical investigations into their therapeutic efficacy.

Purpose of the Study:

• To review and update current evidence on the bioavailability of tocotrienols specifically from human studies.
• To discuss factors influencing tocotrienol bioavailability, including dosage, composition, formulation, and study populations.

Main Methods:

• Systematic review of existing human studies on tocotrienol bioavailability.
• Analysis of data from five studies suggesting alternative absorption pathways for tocotrienols.
• Examination of outcomes from 24 clinical studies focusing on variables like dosage, population, and formulation.

Main Results:

• Evidence suggests tocotrienols may utilize alternative absorption pathways, with significant amounts detected in HDL particles and adipose tissue.
• Oral tocotrienol absorption is enhanced when consumed with food or in self-emulsifying preparations.
• Inconsistent bioavailability results across studies highlight the impact of dosage, formulation variations, control diets, and diverse study populations (healthy, smokers, patients).

Conclusions:

• Tocotrienols exhibit unique biological activities, but their bioavailability in humans is variable and influenced by multiple factors.
• Further research is needed to optimize tocotrienol formulations and understand their absorption dynamics in different populations for effective therapeutic use.
• Standardization of study designs, including diet control and formulation specifics, is essential for consistent and reliable tocotrienol bioavailability data.