The colourless carotenoids phytoene and phytofluene: From dietary sources to their usefulness for the functional foods and nutricosmetics industries

Carotenoids are dietary compounds of great interest in food science, nutrition and health due to the fact that some of them can be converted into retinoids exhibiting vitamin A activity, their role as natural colorants and a growing body of evidence indicating that they may provide health benefits. This is not all as some carotenoids accumulate in human skin where, besides promoting health by protecting against UV damage, they can provide cosmetic benefits by contributing to improved skin colour or improving other skin characteristics. Of the over 800 carotenoids described, only very few of them are colourless. Two of these, phytoene and phytofluene, are attracting much attention recently as they are taken with the diet, they are bioavailable and there are studies of diverse nature indicating that they could be beneficial for health. However, they have not been as extensively studied as the other major bioavailable carotenoids, namely lutein, zeaxanthin, β-cryptoxanthin, β-carotene and lycopene. The aim of this review is to summarize much of the research carried out on these carotenoids, highlighting their potential in the context of functional foods and the related area of nutricosmetics.