Olive OilPolyphenols Enhance High-Density Lipoprotein Function in Humans: A Randomized Controlled Trial

Hernáez A, Fernández-Castillejo S, Farràs M, et al.
Arterioscler Thromb Vasc Biol. 2014 Jul 24. pii: ATVBAHA.114.303374

Background

It has previously been shown that olive oil polyphenols increased HDL-c levels dose-dependently [1]. Although low HDL-c levels are strongly associated with high cardiovascular (CV) risk [2], recent data indicate that higher HDL-c levels do not imply a reduction in the risk of experiencing a myocardial infarction [3]. A strategy may be to not only increase HDL-c, but also to enhance its biological function.
Olive oil polyphenols have been demonstrated to be able to enhance expression of genes related to HDL metabolism and function [4], but no randomised controlled study in humans has been conducted to confirm this. This study therefore aimed to elucidate whether 3 weeks consumption of high-polyphenol content olive oil (HPCOO) is able to enhance HDL activity and quality characteristics. This was tested in a cross-over design with healthy volunteers, with low-polyphenol content olive oil as control condition.

Main results

• Cholesterol efflux capacity from THP-1 macrophages of the participants’ HDL fraction was significantly higher after the HPCOO intervention, as compared to the low-polyphenol content olive oil (P=0.043).
• The main metabolites of olive oil polyphenols bind to HDL in a dose-dependent manner, after the HPCOO intervention, as compared to baseline and the control condition. Metabolites of olive oil polyphenols were positively associated with cholesterol efflux capacity.
• Higher levels of larger HDL were detected in plasma after the HPCOO intervention, as compared to baseline or the low polyphenol olive oil intervention. Levels of small HDL were lower.
• Triglyceride content in the HDL core was significantly decreased with HPCOO as compared to baseline (P=0.049). There was a tendency for it to be statistically significantly different from the control olive oil (P=0.057). HDL particle fluidity was significantly increased with HPCOO as compared with baseline (P=0.033).

Conclusion

These results shows that consumption of olive oil polyphenols during three weeks induced enhancement of the main HDL biological function, namely its cholesterol efflux capacity. In addition, biochemical properties of the lipoprotein were also altered, which may have contributed to the functional enhancement.
Based on these results, it can be hypothesised that better binding of olive oil polyphenols to HDL would increase the fluidity (through local antioxidative properties of the bound polyphenols). This in turn may increase HDL capacity to promote cholesterol efflux from peripheral cells, towards the liver to be metabolised and excreted. The data are in line with previous evidence that suggests that consumption of olive oil polyphenols helps to reduce CV risk.

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References

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4. Farràs M, Valls RM, Fernández-Castillejo S, et al. Olive oil polyphenols enhance the expression of cholesterol efflux related genes in vivo in humans. A randomized controlled trial. J Nutr Biochem. 2013;24:1334–1339.