Exploring the health benefits of the Mediterranean diet: polyphenols, olive oil and longevity

iStock photoMany different food types – from the school dinner favorite broccoli to traditional Chinese goji berries – have been termed ‘superfoods’ in recent years, due to their reported beneficial effects on longevity and disease prevention. The health gains of these foods are largely attributed to their antioxidant content, but evidence behind the benefits of consuming these foods is limited, and relatively little is known about the individual nutrients conferring disease protection.

To further unravel the protective effects of antioxidant consumption, new research published in BMC Medicine as part of our Metabolism, Diet and Disease article collection has investigated the impact of polyphenols, a type of antioxidant containing phenolic compounds, on overall mortality risk.

In a reanalysis of the Prevención con Dieta Mediterránea (PREDIMED) trial, Anna Tresserra-Rimbau and colleagues showed that in people with elevated cardiovascular disease (CVD) risk, those reporting a Wikimedia commons (Mick Stephenson)high polyphenol intake have reduced mortality risk.

The authors broke down the analysis by polyphenol class, demonstrating that stilbenoids and lignans are most strongly associated with this protective effect on mortality. Stilbenoids are found in grape skins and concentrated in red wine, whereas flax seed, sesame seed, cruciferous vegetables and cereals contain high levels of lignans.

These findings add to mounting evidence for the health benefits of polyphenol consumption, and suggest that consuming foods containing stilbenoids and lignans in particular could be linked to improved longevity.

An important source of dietary polyphenols is olive oil, and in a related analysis of the PREDIMED trial, Marta Guasch-Ferré and colleagues investigated whether increasing olive oil consumption, as part of advice to follow a Mediterranean diet in those at high cardiovascular risk, has an effect on longevity. The authors demonstrated that increased olive oil consumption is associated with decreased incidence of CVD and overall mortality.

olive oilThe association was particularly strong for extra-virgin olive oil, with a 10g/day increase in extra-virgin olive oil linked to a 10% reduction in CVD. These results provide evidence for the health benefits of extra-virgin olive oil consumption, and the authors conclude that:

“Our findings underscore olive oil consumption as one of the key components of the Mediterranean diet for cardiovascular disease prevention.”

The Mediterranean diet has been linked to a number of health benefits, as outlined in our previous blog. While the recent PREDIMED studies provide important information on which individual components of the Mediterranean diet may confer its beneficial effects, there have been concerns that too much focus on individual foods may encourage unhealthy eating overall. Alison Hornby, dietitian and spokesperson for the British Dietetic Association, cautions that:

“If people mistakenly believe they can ‘undo’ the damage caused by unhealthy foods by eating a superfood, they may continue making routine choices that are unhealthy and increase their risk of long-term illness”

Hornby recommends that emphasis should be placed on eating a balanced diet, such as the Mediterranean diet, in order to decrease the risk of chronic disease and early mortality.

We hope that the results of the two PREDIMED studies will inform public health policy on eating a healthy and balanced diet, and look forward to further research investigating the long-term benefits of consuming polyphenol-rich foods.

In recognition of our second annual conference (Metabolism, Diet and Disease 2014: Cancer and Metabolism) our Metabolism, Diet and Disease article collection, published in collaboration with our sister journal BMC Biology, remains open for submissions.

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