State of the Art on Functional Virgin Olive Oils Enriched with Bioactive Compounds and Their Properties

Abstract

Virgin olive oil, the main fat of the Mediterranean diet, is per se considered as a functional food-as stated by the European Food Safety Authority (EFSA)-due to its content in healthy compounds. The daily intake of endogenous bioactive phenolics from virgin olive oil is variable due to the influence of multiple agronomic and technological factors. Thus, a good strategy to ensure an optimal intake of polyphenols through habitual diet would be to produce enriched virgin olive oil with well-known bioactive polyphenols. Different sources of natural biological active substances can be potentially used to enrich virgin olive oil (e.g., raw materials derived from the same olive tree, mainly olive leaves and pomaces, and/or other compounds from plants and vegetables, mainly herbs and spices). The development of these functional olive oils may help in prevention of chronic diseases (such as cardiovascular diseases, immune frailty, ageing disorders and degenerative diseases) and improving the quality of life for many consumers reducing health care costs. In the present review, the most relevant scientific information related to the development of enriched virgin olive oil and their positive human health effects has been collected and discussed.

Keywords: endothelial dysfunction; enriched olive oil; functional food; health; intestinal immune function; oxidative stress; phenolic compounds.

Figure 1

Cellular enzymes and mechanisms involved in protection from reactive oxygen species (ROS). SOD: Superoxide dismutase; CAT: Catalase; GPx: Glutathione peroxidase; GCL: Glutamate-cysteine ligase; GR: Glutathione reductase; GSH: Glutathione; GSSH: Oxidized glutathione; NADP⁺/NADPH: Nicotinamide adenine dinucleotide phosphate (oxidased/reduced).

Figure 2

Postprandial time-course changes in ischemic reactive hyperemia (IRH) after ingestion of the different olive oils (OOs). CVOO: control virgin olive oil; FVOO: functional virgin olive oil enriched with its phenolic compounds (500 ppm). *, P < 0.05 versus baseline; †, P < 0.05 versus VOO at the same time-point. Figure reproduced with permission from Valls et al. [85].

Figure 3

Role of low-density lipoproteins (LDLs) and early stages involved in atherosclerosis. Figure reproduced with permission from Barter [91]. LDL-C: LDL-cholesterol; MCP-1: Monocyte chemotactic protein-1.

Figure 4

Effect of hydroxytyrosol (HTyr, or HT) and HT metabolites on E-selectin, P-selectin, VCAM-1, ICAM-1, and MCP-1 protein secretion in human aortic endothelial cells (HAEC) stimulated by TNF-α after 24 h. Human aortic endothelial cells were co-incubated with HT or HT metabolites at 1, 2, 5, and 10 μM and TNF-α (10 ng/mL) for 24 h. (A) Effect of HT or HT metabolites on E-selectin protein secretion. (B) Effect of HT or HT metabolites on P-selectin protein secretion. (C) Effect of HT or HT metabolites on VCAM-1 protein secretion. (D) Effect of HT or HT metabolites on ICAM-1 protein secretion. (E) Effect of HT or HT metabolites on MCP-1 protein secretion. Results are expressed as the percentage of soluble cellular adhesion molecules or chemokine protein secretion adjusted by total cellular protein and standard error of the mean (SEM; error bars). *, P < 0.05 versus TNF-α alone. †, P < 0.05 compared between HT and HT metabolites at the same concentration. Figure reproduced with permission from Catalán et al. [13]. TCP: Tissue culture plate; TNF-α: Tumour necrosis factor-alpha; VCAM-1: Vascular cell adhesion molecule-1; ICAM-1: Intercellular adhesion molecule-1; MCP-1: Monocyte chemotactic protein-1.

Figure 5

Changes in atherogenic lipoprotein particle atherogenic ratios and lipoprotein insulin resistance index (LP-IR) after consumption of functional olive oils versus natural virgin olive oil (VOO). FVOO: Functional virgin olive oil enriched with its phenolic compounds (500 ppm); FVOOT: Functional olive enriched with its phenolic compounds (250 ppm) and those from thyme (250 ppm). *, P < 0.001 versus VOO. Differences between functional olive oils are indicated by square brackets with the corresponding significance. Figure reproduced with permission from Fernández-Castillejo et al. [34]. HDL: high-density lipoprotein; HDL-C: HDL-cholesterol; LDL-P: low density lipoprotein-particles; HDL-P: HDL-particles; s-HDL: small HDL; l-HDL: large HDL.

Figure 6

Stages involved in the reverse cholesterol transport (RCT), which favours the cholesterol transport to the liver for its excretion. Figure reproduced with permission from Oliveira and De Faria, 2011 [99]. LDLr: LDL receptors; LRP: LDL receptor-related proteins; CE: Cholesteryl ester; SR-BI: Scavenger receptor class B type I; VLDL: Very low-density lipoprotein; LH: Hepatic lipase; IDL: Intermediate-density lipoproteins; TG: Triglycerides; CETP: Cholesterylester transfer protein; LCAT: lecithin cholesterol acyl transferase; ABCA1/G1: ATP binding cassette transporter A1 or G1; Apo AI: Apolipoprotein AI.

Figure 7

Venn diagram showing intersections of proteins differentially expressed after VOO, FVOO, and FVOOT interventions. Proteins are presented with their gene encode symbol. Red proteins: Up-regulated; Green proteins: Down-regulated. Figure reproduced with permission from Pedret et al. [100]. VOO: Virgin olive oil; FVOO: Functional virgin olive oil enriched with its own phenolic compounds; FVOOT: Functional virgin olive oil enriched with its own phenolic compounds plus complementary phenols from thyme.