Research: Can a diet high in nuts and olive oil lower your risk or reverse metabolic syndrome?

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What does a Mediterranean Diet do to diabetes risk?  

Metabolic Syndrome infographic
Metabolic Syndrome infographic

First, let’s look at what metabolic syndrome is.  Metabolic syndrome is a pre-drome for diabetes are heart disease.  It is simply the syndrome of central obesity, elevated blood pressure, insulin resistance, abnormal cholesterol levels, and truncal or central obesity.  The pre-drome or precursor to diabetes and heart disease is at epidemic levels in the United States and is the warning shot across our bow that we are going to have a potential health care crisis in 10-20 years.  

In researching nuts a few days ago, I came across a published article from 2014 that caught my attention.  This journal article was published in the Candian Medical Journal and highlighted the finding from a secondary analysis of the PREDIMED trial​[1]​.  This study was a multicentre, randomized trial done between October 2003 and December 2010 that involved men and women (age 55–80 yr) at high risk for cardiovascular disease.  The Spanish researchers involved in this study evaluated 5801 men and women participants of with 64% of them showing signs of metabolic syndrome at the onset of the study.  The subjects were placed in one of three groups with a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with nuts or advice on following a low-fat diet (the control group).  The latter group is consistent with the typical American diet and current recommendations from the USDA and most healthy groups in the United States.  

So what did either intervention reduce the onset of metabolic syndrome?  Over 4.8 years of study, metabolic syndrome developed in 960 of the 1919 participants who did not have the condition at baseline.  So in other words, about 50% of those who did not have metabolic syndrome developed it during the study.  The risk of developing metabolic syndrome did not differ between participants assigned to the control diet and those assigned to either of the Mediterranean diets.  So in other words, a Mediterranean diet does not appear to stop the onset of metabolic syndrome.  

Central Obesity
Central Obesity

So did either intervention reverse metabolic syndrome?  Metabolic syndrome was reversed in 958 of the 3392 participants or 28% of those who had metabolic syndrome at the onset of the study.  Participants on either Mediterranean diet were more likely to undergo reversion.  Participants in the group receiving olive oil supplementation had a statistically significant decrease in both central obesity and high fasting glucose and participants in the group supplemented with nuts showed a significant reduction in central obesity. 

The bottom line: A Mediterranean diet supplemented with either extra virgin olive oil or nuts does not appear to stop patients from acquiring metabolic syndrome, but such diets are more likely to cause a reversal of the condition if you already have it.  Researchers postulated that “An energy-unrestricted Mediterranean diet may be useful in reducing the risks of central obesity and hyperglycemia in people at high risk of cardiovascular disease.​[2]​”  I would suspect that if you control your weight and caloric intake and also add an energy-unrestricted Mediterranean diet that you might be more successful at reducing your metabolic syndrome risk if you do not already have it.  Further research is needed in this area because it was not the primary focus of the study.  

[1]Babio et al., “Mediterranean Diets and Metabolic Syndrome Status in the PREDIMED Randomized Trial.”
[2]Babio et al., “Mediterranean Diets and Metabolic Syndrome Status in the PREDIMED Randomized Trial.”


  1. Babio, N, E Toledo, R Estruch, E Ros, MA Martínez-González, O Castañer, M Bulló, et al. “Mediterranean Diets and Metabolic Syndrome Status in the PREDIMED Randomized Trial.” CMAJ : Canadian Medical Association Journal = Journal de l’Association Medicale Canadienne 186, no. 17 (November 18, 2014): E649-57. [PubMed]
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About the Author

I am a family physician who has served in the US Army. In 2016, I found myself overweight, out of shape, and unhealthy, so I made a change to improve my health. This blog is the chronology of my path to better health and what I have learned along the way.

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