β-Carotene in the human body: metabolic bioactivation pathways – from digestion to tissue distribution and excretion

• Published in: Proceedings of the Nutrition Society Vol. 78; no. 1; pp. 68 - 87
• Main Authors: Bohn, Torsten, Desmarchelier, Charles, El, Sedef N., Keijer, Jaap, van Schothorst, Evert, Rühl, Ralph, Borel, Patrick
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.02.2019; Cambridge University Press (CUP)
• Subjects: beta Carotene - metabolism; beta-carotene; bioactive properties; Bioavailability; Biological activity; Biological Availability; blood serum; Carotene; Carotenoids; chronic diseases; Conference on ‘Nutrient–nutrient interaction’; critical control points; Diabetes; Digestion - physiology; Enzymes; Esters; Excretion; Fatty acids; Food; Food and Nutrition; Gene expression; genes; hormone receptors; Human body; Human subjects; Humans; Life Sciences; Ligands; Lipids; Metabolic Networks and Pathways - physiology; Metabolism; Metabolites; Nuclear receptors; Nutrition Society Scottish Section Meeting 2018; Oxygenase; Particle size; Physiology; Receptors; Retinoic acid; retinoic acid receptors; Retinoids; Signal transduction; Signaling; Studies; Symposium 2: Nutrient interactions and their role in protection from chronic diseases; tissue distribution; Tissue Distribution - physiology; Vitamin A; β-Carotene; Vitamin A; Nuclear hormone receptor; Absorption; SNPs; Apo-carotenoids; Micellisation; Retinoic acid
• ISSN: 0029-6651; 1475-2719; 1475-2719
• DOI: 10.1017/S0029665118002641

β-Carotene intake and tissue/blood concentrations have been associated with reduced incidence of several chronic diseases. Further bioactive carotenoid-metabolites can modulate the expression of specific genes mainly via the nuclear hormone receptors: retinoic acid receptor- and retinoid X receptor-mediated signalling. To better understand the metabolic conversion of β-carotene, inter-individual differences regarding β-carotene bioavailability and bioactivity are key steps that determine its further metabolism and bioactivation and mediated signalling. Major carotenoid metabolites, the retinoids, can be stored as esters or further oxidised and excreted via phase 2 metabolism pathways. In this review, we aim to highlight the major critical control points that determine the fate of β-carotene in the human body, with a special emphasis on β-carotene oxygenase 1. The hypothesis that higher dietary β-carotene intake and serum level results in higher β-carotene-mediated signalling is partly questioned. Alternative autoregulatory mechanisms in β-carotene / retinoid-mediated signalling are highlighted to better predict and optimise nutritional strategies involving β-carotene-related health beneficial mediated effects.