Tocopherols and Tocotrienols—Bioactive Dietary Compounds; What Is Certain, What Is Doubt?

Abstract

Tocopherols and tocotrienols are natural compounds of plant origin, available in the nature. They are supplied in various amounts in a diet, mainly from vegetable oils, some oilseeds, and nuts. The main forms in the diet are α- and γ-tocopherol, due to the highest content in food products. Nevertheless, α-tocopherol is the main form of vitamin E with the highest tissue concentration. The α- forms of both tocopherols and tocotrienols are considered as the most metabolically active. Currently, research results indicate also a greater antioxidant potential of tocotrienols than tocopherols. Moreover, the biological role of vitamin E metabolites have received increasing interest. The aim of this review is to update the knowledge of tocopherol and tocotrienol bioactivity, with a particular focus on their bioavailability, distribution, and metabolism determinants in humans. Almost one hundred years after the start of research on α-tocopherol, its biological properties are still under investigation. For several decades, researchers’ interest in the biological importance of other forms of vitamin E has also been growing. Some of the functions, for instance the antioxidant functions of α- and γ-tocopherols, have been confirmed in humans, while others, such as the relationship with metabolic disorders, are still under investigation. Some studies, which analyzed the biological role and mechanisms of tocopherols and tocotrienols over the past few years described new and even unexpected cellular and molecular properties that will be the subject of future research.

Anything New under the Sun? An Update on Modulation of Bioactive Compounds by Different Wavelengths in Agricultural Plants

“…This review specifically focuses on the influence of the different light radiations, from red–far-red to UV-B, on the main classes of secondary metabolites, such as phenolic compounds, terpenoids, tocopherols, glucosinolates, and ascorbic acid in agricultural plant species, because of the recognised role that these compounds generally play as promoters of human wellness [ 43 , 44 , 45 , 46 ]. UV-C radiation was reported to modulate accumulation of health-promoting compounds in different plants and fruits of food interest, such as tomato fruit [ 47 ], bean seedlings [ 48 ] and peanut sprouts [ 49 ], this review exclusively discusses the effects of those wavelengths that reach the Earth’s surface, and to which plants have adapted fine-tuning perception mechanisms and consequent molecular and biochemical responses through evolution.…”

Effect of Nutrition on Age-Related Metabolic Markers and the Gut Microbiota in Cats

“…Metabolites of tocopherols, which are vitamin E compounds with antioxidant activity [38], were higher in both serum and feces from cats fed the test food compared with the control food. A prior study showed that levels of vitamin E were lower in patients with CKD compared with healthy controls [39].…”

Differential Mechanisms of Action and Efficacy of Vitamin E Components in Antioxidant Cytoprotection of Human Retinal Pigment Epithelium

“…Many plant-based vitamin E sources contain predominantly γT and lesser concentrations of other tocopherols ( Jiang et al, 2001 ; Szewczyk et al, 2021 ). Since North American diets contain more γT than other tocopherols, higher levels of γT tocopherol are ingested, but it is more rapidly eliminated from the body (in bile).…”