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Several functions of HDL particles improved by Mediterranean diet

Several functions of HDL particles improved by Mediterranean diet

Mediterranean Diet Improves High-Density Lipoprotein Function in High-Cardiovascular-Risk Individuals - A Randomized Controlled Trial

Hernáez Á, Castañer O, Elosua R, et al. - Circulation. 2017;135:633-643

Background

The biological functions of high-density lipoproteins (HDLs), such as cholesterol transport, HDL antioxidant properties and HDL vasodilatory capacity, contribute to explaining the cardioprotective role of the lipoproteins, beyond measuring levels only. Several nutrients and food that are part of a traditional Mediterranean diet (TMD) may improve these functions, as shown by previous trials [1-4].

However, no evidence of the effects of a whole TMD on HDL properties has been reported. Therefore, this study assessed whether long-term (1 year) consumption of a TMD, enriched with virgin olive oil or nuts, improved different biological functions of HDL in a random selection of PREDIMED study patients (n=296, 4.14% of total trial). 100 Patients received a TMD diet with supplementary virgin olive oil, 100 with supplementary nuts and 96 a low-fat control diet.

Main results

Conclusion

After 1 year, a TMD, especially the one enriched with virgin olive oil, improved several HDL functions, namely cholesterol efflux capacity, cholesterol metabolism, antioxidant/anti-inflammatory properties and vasodilatory capacity, in individuals at high cardiovascular risk. Further studies are warranted to investigate the mechanisms by which a TMD achieves this and whether this results in cardioprotective effects.

Editorial comment

Rader discusses the complexity of the role HDL in cardiovascular diseases in this editorial comment [5]. In this regard, he mentions the ‘HDL flux’ or ‘HDL function’ hypothesis, which “ concept is based on the idea that HDL has a number of putative antiatherogenic functions that may causally affect CVD risk but that are not directly related to simple measures of HDL mass such as HDL-C levels. The best established of the measures of HDL function is HDL cholesterol efflux capacity (CEC), an ex vivo measure of the ability of an individual’s HDL to promote cholesterol efflux from macrophages in cell culture. A number of studies have shown that HDL CEC is inversely associated with prevalent coronary artery disease and incident CVD events even independently of HDL-C levels. Although this is consistent with the concept of a protective effect, it is still only an association that is far from proof of causality.” He notes that interventions that increase CEC are one approach to establish a body of data that CEC could causally protect against atherosclerosis, but that this so far, didn’t yield any rigorous data. Therefore, this dietary study on CEC is of particular interest, he writes. Rader further discusses the results for the low-fat diet group, the differences between the three dietary groups and the mechanisms by which the TMD increases HDL CEC. And he also points out that “it is possible that the TMD, by enhancing HDL function, could slow the progression of AMD in addition to atherosclerosis.” His conclusion is “these results indicate that a Mediterranean diet is a practical lifestyle-focused approach to improving HDL function and has the proven benefit of reducing cardiovascular risk and the potential to reduce the progression of AMD. Whether promotion of HDL CEC causally contributes to the benefits of the Mediterranean diet remains to be established.”

References

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