Olive-oil Phenolics and Health: Potential Biological Properties

Abstract

Extra virgin olive oil, the primary source of oil in the Mediterranean diet, differs significantly in composition from dietary lipids that are consumed by other populations. The several minor constituents of virgin olive oil include vitamins such as alphaand gamma-tocopherols (around 200 ppm) and beta-carotene, phytosterols, pigments, terpenic acids, flavonoids, squalene, and a number of phenolic compounds, such as hydroxytyrosol, usually grouped under the rubric "polyphenols". The antioxidant and enzyme-modulating activities of extra virgin olive oil phenolics, such as their ability to inhibit NF-kB activation in human monocyte/macrophages has been demonstrated in vitro. There is also solid evidence that extra virgin olive oil phenolic compounds are absorbed and their human metabolism has been elucidated. Several activities that might be associated with cardiovascular protection, such as inhibition of platelet aggregation and reduction of plasma rHcy have been demonstrated in vivo. The biologically relevant properties of olive phenolics are described, although further investigations in controlled clinical trials are needed to support the hypothesis that virgin olive oil consumption may contribute to lower cardiovascular mortality.

Extra Virgin Olive Oil Polyphenols: Modulation of Cellular Pathways Related to Oxidant Species and Inflammation in Aging

“…Extensive research highlighted the importance of EVOO polyphenols in limiting NO production in immune system cells, treated with LPS to simulate inflammatory conditions. HT above all [67,104,140] but also oleuropein [67,108] and complex EVOO polyphenols extracts [107,127] were able to impede NO overproduction in monocytes and macrophages. These effects occurred actually not only in these cell types, but also in almost all the tissues studied, both in vitro [129,141] and in vivo [98,142].…”

“…In vitro, EVOO extracts or simple phenols demonstrated, particularly in monocytes and activated macrophages, the ability to inhibit MAPKs activation, which in turn caused inhibition of phosphorylated-IκBα and thus NF-κB expression and translocation into the nucleus. These effects have been noticed in particular in those cells treated with oleuropein aglycone [105], Tyr [98,106], and HT [104], as well as complex phenolic extracts [107,108]. At the intestinal level, the breakdown of the NF-κB inhibitor IkBα was counteracted by EVOO phenolic extracts or by simple phenols HT and Tyr glucuronide and sulfates in intestinal Caco-2 cells, where NF-κB was experimentally activated by a mixture of dietary oxysterols [99] or by LPS [88].…”

Effect of extra virgin olive oil on glycaemia in healthy young subjects

“…Subjects did not modify their diet, with the exception of the consumption of the study oil, so that food intake (apart from added fat replace) before and during the test period was the same. Since most of the recent studies have highlighted a strong correlation between the beneficial properties of EVOO and its phenolic concentration 3, 4, 7, 10, 16, 20, in this research we selected an oil rich in phenolic compounds, with high amounts of secoiridoids, mainly oleuropein derivatives (Table 2). It has been recently pointed out the capacity of 3,4‐DHPE‐EA to prevent amyloid aggregation of human amylin, a hallmark of Type II diabetes 29.…”

“…Olive oil consumption has shown to reduce oxidative damage and cardiovascular risk in European populations 1, 2. Some authors report to have found increased HDL cholesterol 3–5, increased antioxidant capacity 6–8, and gene expression from antioxidant enzymes 6, 9 in intervention periods with participants consuming daily EVOO.…”

“…In addition, previous papers also reported decreased levels of blood pressure 5, 10, platelet aggregation 5, 11, 12, homocysteine 12, triglycerides 6, 13, 14, LDL cholesterol, and total cholesterol levels 5, 6, 13, 14, in intervention studies with EVOO. Oxidized LDL 1, 3, 4, 7, 15, 16, oxidative stress in several tissues 4–6, 11, 17–19 and DNA oxidative damage 20 have also shown to be reduced mainly due to the effect of polyphenols from EVOO.…”