A global perspective on carotenoids: Metabolism, biotechnology, and benefits for nutrition and health

Abstract

Carotenoids are lipophilic isoprenoid compounds synthesized by all photosynthetic organisms and some non-photosynthetic prokaryotes and fungi. With some notable exceptions, animals (including humans) do not produce carotenoids de novo but take them in their diets. In photosynthetic systems carotenoids are essential for photoprotection against excess light and contribute to light harvesting, but perhaps they are best known for their properties as natural pigments in the yellow to red range. Carotenoids can be associated to fatty acids, sugars, proteins, or other compounds that can change their physical and chemical properties and influence their biological roles. Furthermore, oxidative cleavage of carotenoids produces smaller molecules such as apocarotenoids, some of which are important pigments and volatile (aroma) compounds. Enzymatic breakage of carotenoids can also produce biologically active molecules in both plants (hormones, retrograde signals) and animals (retinoids). Both carotenoids and their enzymatic cleavage products are associated with other processes positively impacting human health. Carotenoids are widely used in the industry as food ingredients, feed additives, and supplements. This review, contributed by scientists of complementary disciplines related to carotenoid research, covers recent advances and provides a perspective on future directions on the subjects of carotenoid metabolism, biotechnology, and nutritional and health benefits.

An Overview of Carotenoids, Apocarotenoids, and Vitamin A in Agro‐Food, Nutrition, Health, and Disease

“…Mammalians express an enzyme (referred to as β,β‐carotene 9′,10′‐dioxygenase, BCO2) that catalyzes the eccentric cleavage (at both the 9,10 and 9′,10′ double bonds) of both provitamin A carotenoids (PAC) and non‐PACs producing both non‐volatile apocarotenoids and volatile compounds . The apocarotenoids stemming from the oxidative cleavage of dietary carotenoids are attracting much attention because they may contribute to positive health‐promoting actions by mechanisms such as the intervention in cell signaling pathways …”

“…Although the attention in the following sections will be focused on carotenoids, it is to be noted that some actions of carotenoids could arise to a greater or lesser extent from derivatives originated through structural modifications of a parent carotenoid molecule, including cleavage. Examples would be VA or lycopene derivatives (such as apo‐10′‐lycopenal, apo‐10′‐lycopenol, or apo‐10′‐lycopenoic acid), which have attracted considerable interest in this context …”

“…However, ample evidence has accumulated indicating that carotenoids (and/or their derivatives) are health‐promoting compounds. Similarly, studies indicating that in addition to an ability to protect the skin, carotenoids can provide cosmetic benefits that are coming to light …”

“…It is estimated that the diets of humans usually contain ≈50 carotenoids . The main bioavailable dietary carotenoids are lutein, zeaxanthin, β‐cryptoxanthin, α‐carotene, β‐carotene, lycopene, phytoene, and phytofluene, which are the principal carotenoids in human fluids and tissues ( Figure ) .…”

“…They are still largely known in the context of food science, nutrition, and health as colorants and some of them exhibit vitamin A (VA) activity. There is ample evidence that carotenoids (and their derivative products and metabolites) may be involved in health‐promoting biological actions in humans . Thus, carotenoids (most notably lutein) are among the bioactives for which the need to establish recommended dietary intakes (RDI) has been discussed .…”