Immunometabolic effects of β-carotene and vitamin A in atherogenesis

Carotenoids are a diverse group of lipids produced by photosynthetic organisms, and therefore, these compounds are major components of healthy diets. Carotenoids are among the most extensively studied micronutrients to date due to their antioxidant and provitamin A properties. β-carotene is one of the most abundant carotenoids in our diet, but more importantly, it is the main vitamin A precursor in humans. This review summarizes the key metabolic steps involved in vitamin A formation in mammals. It also highlights the recent advancements in the bioactive properties of β-carotene and vitamin A in relationship with atherosclerotic cardiovascular disease. We examine the dual effect retinoic acid, the transcriptionally active form of vitamin A, has on lipid metabolism and atherosclerosis development. Finally, we cover recent findings on the immunomodulatory role retinoic acid plays in macrophages and T cells in the context of atherosclerosis development and resolution.