Role of vitamin A in health and illness

Abstract

Introduction. Vitamin A is an essential substance for human well-being and survival. It plays a crucial role in many physiological processes, including growth and differentiation of target tissues, reproduction, proper functioning of the retina and modulation of the immune system. Vitamin A deficiency leads to increased risk of severe infections, numerous diseases and pathological conditions, including disorders of vision, bones, epithelial tissue and immunity. It remains one of the main causes of preventable blindness in children. Nonetheless, excessive intake of vitamin A can also cause serious health problems. Objective. The aim of this study is to describe and summarize current knowledge about the role of vitamin A in the human organism, as well as to provide general information on its supplementation. State of Knowledge. Vitamin A is a group of similar organic compounds that cannot be synthesized in the human body, and therefore has to be included in the diet. Vitamin A influences the human body since foetal life. Both deficiency and an excess of vitamin A may cause serious complications. The main sources of the vitamin are meat, fish, poultry and dairy products. Its precursors, such as carotenoids, are present in fruit and vegetables. It is stored mainly in the liver and adipose tissue. Vitamin A has antioxidative attributes. Conclusion. An adequate intake of vitamin A is crucial for maintaining health and well-being, and deficiency as well as overdose of this vitamin may cause serious complications and diseases.