Vitamin A Update: Forms, Sources, Kinetics, Detection, Function, Deficiency, Therapeutic Use and Toxicity.

Alejandro Carazo,Kateřina Macáková,Lenka Kujovská Krčmová,Přemysl Mladěnka,Kateřina Matoušová,Michele Protti

doi:10.3390/nu13051703

Alejandro Carazo, Kateřina Macáková + Show 4 more

Open Access

https://doi.org/10.3390/nu13051703

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Abstract

Vitamin A is a group of vital micronutrients widely present in the human diet. Animal-based products are a rich source of the retinyl ester form of the vitamin, while vegetables and fruits contain carotenoids, most of which are provitamin A. Vitamin A plays a key role in the correct functioning of multiple physiological functions. The human organism can metabolize natural forms of vitamin A and provitamin A into biologically active forms (retinol, retinal, retinoic acid), which interact with multiple molecular targets, including nuclear receptors, opsin in the retina and, according to the latest research, also some enzymes. In this review, we aim to provide a complex view on the present knowledge about vitamin A ranging from its sources through its physiological functions to consequences of its deficiency and metabolic fate up to possible pharmacological administration and potential toxicity. Current analytical methods used for its detection in real samples are included as well.

Highlights

Introduction and Forms of Vitamin AVitamin A is a fat-soluble life-essential group of compounds both of animal and vegetal origin characterized by an unsaturated isoprenoid chain structure
The basic vitamin A string is hidden in their structures, and they are similar to other retinoids in their interaction with retinoid receptors
It is a common belief that these preparations are safe products, but several thousand intoxications are reported every year due to using these products

Summary

Introduction

Introduction and Forms of Vitamin AVitamin A is a fat-soluble life-essential group of compounds both of animal and vegetal origin characterized by an unsaturated isoprenoid chain structure. A forms share a similar structure and the same physiological functions in an organism These compounds can be classified as retinoids, including compounds with a common structure of four isoprenoid units being of either a natural or synthetic origin (Figure 1). The basic vitamin A string is hidden in their structures, and they are similar to other retinoids in their interaction with retinoid receptors. All these compounds are liposoluble and, unlike water-soluble vitamins, are accumulated in the body, especially in the liver and adipose tissue.This represents, on one hand, an advantage since temporal deprivation of vitamin A intake is not associated with clinical symptoms, but on the other hand, accumulation with subsequent toxicity can appear

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