Anti-DNA Damage Mechanisms and the Role of Carotenoids, Vitamin A, and Its Derivatives.

All forms of vitamin A have a similar structure and physiological functions in the body. These compounds can be classified as retinoids, including moieties with a common structure of four isoprenoid units of natural or synthetic origin. Vitamin A is generally uptake from products of animal origin (retinol and its derivatives) or from plants as provitamin A (carotenoids). Vitamin A is fat-soluble, so it is easily absorbed and transported in the body. The main storage sites are the liver and adipose tissue. Excessive amounts of the vitamin may lead to the development of different abnormal processes in the human body. Apart from being crucial for retina conditions and functions and the immune system, vitamin A is also deeply involved in DNA repair mechanisms. Its antioxidant nature helps to reduce the oxidative damage to DNA by neutralizing free radicals and thus decreasing the oxidative stress. On the other hand, vitamin A deficiency leads to lower antioxidant enzyme activity, which results in the weakening of the defense system against free radicals. This study aims to elucidate the mechanisms of DNA repair and determine the role of carotenoids, vitamin A, and its derivatives as contributing factors in this process. This review synthesizes the current knowledge on the dual role of vitamin A in DNA integrity by examining the conditions under which it acts as a genotoxic agent versus a facilitator of DNA repair. This article also discusses the role of vitamin A in inhibiting oxidative stress and its anti- and pro-cancer impact.