Carotenoids: Dietary Sources, Extraction, Encapsulation, Bioavailability, and Health Benefits-A Review of Recent Advancements

Abstract

Natural carotenoids (CARs), viz. β-carotene, lutein, astaxanthin, bixin, norbixin, capsanthin, lycopene, canthaxanthin, β-Apo-8-carotenal, zeaxanthin, and β-apo-8-carotenal-ester, are being studied as potential candidates in fields such as food, feed, nutraceuticals, and cosmeceuticals. CAR research is advancing in the following three major fields: (1) CAR production from natural sources and optimization of its downstream processing; (2) encapsulation for enhanced physical and chemical properties; and (3) preclinical, clinical, and epidemiological studies of CARs' health benefits. This review critically discusses the recent developments in studies of the chemistry and antioxidant activity, marketing trends, dietary sources, extraction, bioaccessibility and bioavailability, encapsulation methods, dietary intake, and health benefits of CARs. Preclinical, clinical, and epidemiological studies on cancer, obesity, type 2 diabetes (T2D), cardiovascular diseases (CVD), osteoporosis, neurodegenerative disease, mental health, eye, and skin health are also discussed.

Keywords: astaxanthin; cancer; cardiovascular diseases (CVDs); diabetes; lycopene; microalgae; neurodegenerative disease; pigments; vitamin A; β-carotene.

Figure 1

The molecular structure of chromophore of (all-E)-β-carotene (A), responsible for the absorption of light in the visible range. The absorbance spectrum of (all-E)-β-carotene (B) is from carrots recorded using a diode array detector (DAD) in the solvent system previously used in our study [29] (unpublished data).

Figure 2

The lipid peroxyl radical (LOO•) scavenging/detoxification by carotenoids (CARs). The carotenoid radical cation (CAR•+) can be regenerated in the presence of tocopherol (vitamin E), ascorbate (vitamin C), and glutathione.

Figure 3

The marketing trends of carotenoids. Source: https://www.bccresearch.com, accessed on 25 February 2022.

Figure 4

The dietary carotenoids obtained from the major fruits and vegetables. From top to bottom, (1) green leafy vegetables, (2) pumpkin and carrot, (3) tomatoes, (4) red paprika, and (5) orange.

Figure 5

The presence of two unmodified β-ionone rings in one molecule of β-carotene can provide two molecules of retinol (vitamin A; 100% provitamin A activity), while α-carotene and β-cryptoxanthin contain only one β-ionone ring structure (50% provitamin A activity).

Figure 6

The antioxidant (in normal cells) and pro-oxidant properties of carotenoids regulate the reactive oxygen species (ROS) and modulate the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB); nuclear factor-erythroid 2-related factor 2 (Nrf2), responsible for apoptosis of cancer cells; and survival of normal cells. Abbreviations: BAX, B-cell lymphoma 2 associated X; Bcl-2, B-cell lymphoma 2; PARP, poly (ADP-ribose) polymerase; PGE2, prostaglandin E2; TNF-α, tumor necrosis factor-alpha.

Figure 7

Carotenoids block the phosphoinositide 3-kinase (PI3K)/phosphorylated protein kinase B (PKB or Akt)/mechanistic target of rapamycin (mTOR) signaling pathways, thus reducing tumor cell initiation, progression, and metastasis. Abbreviations: Bcl-2: B-cell lymphoma 2: IGF: Insulin-like growth factor: MMP9: Matrix Metallopeptidase 9.