PREDIMED is one of the most influential health studies of the past decade. It confirms the power of the Mediterranean diet with nuts to prevent cardiovascular disease.  This large Spanish study involved 7,447 people aged 55-80 years at high cardiovascular risk, who were placed on different study diets and followed up over several years to assess their effects. 

A Mediterranean diet supplemented with nuts, and a Mediterranean diet supplemented with olive oil, both reduced the risk of cardiovascular events by 30% compared with the control (usual) diet. 

This dietary intervention also improved metabolic syndrome, diabetes, weight and brain function. 

What is the Mediterranean diet?  

The Mediterranean diet is based on the traditional healthy eating and cooking habits of those countries bordering the Mediterranean Sea. The diet is based on eating primarily plant-based products including vegetables, fruit, whole grains, legumes, nuts, seeds, herbs and spices. It encourages frequent intake of fish and shellfish, moderate consumption of wine with meals, and low intake of red and processed meat, milk and milk products and simple sugars. Olive oil is encouraged as the main culinary fat.

A smorgasbord of powerful benefits

The study found the Mediterranean diet supplemented with virgin olive oil or nuts can deliver a host of health benefits related to cardiovascular disease, diabetes, metabolic syndrome and brain health. 

These include:

• An anti-inflammatory effect on the cardiovascular system  
• Reduced cardiovascular events in people at high cardiovascular risk. This included myocardial infarction, stroke and death from cardiovascular causes. 
• Inverse association between following the diet and key cardiovascular risk factors including diabetes, hypertension, dyslipidemia and obesity 
• Reduced waist circumference, particularly in people with diabetes  
• Reduction in diabetes incidence compared to those following the low fat diet, without any reduction in body weight or increase in physical exercise 
• Improved insulin resistance 
• Lower prevalence of metabolic syndrome. Metabolic syndrome refers to a set of conditions that often occur together that increase risk of diabetes, stroke and heart disease. These include obesity, high blood pressure, high triglycerides, low levels of HDL (good) cholesterol, and insulin resistance.  
• Improved overall brain health and potential to counter-act age-related cognitive decline including Alzheimer’s disease and dementia 
• Reversal of fatty liver, which can increase risk for type-2 diabetes and liver cancer   

The mental health benefits of the Mediterranean diet

More recently, an Australian study (The SMILES Trial, Jacka, Opie et al 2017) has shown that the Mediterranean diet with olive oil and nuts may offer a powerful means of combating depression. 

A study of people suffering from clinical depression saw 32% on the Mediterranean diet experience a remission in depression symptoms, compared to just 8% in the control group receiving standard care with no diet change. The more closely they adhered to a Mediterranean diet, the lower their score for depression and anxiety. These are significant findings.

Nuts: a powerful addition to the Mediterranean diet 

The advantages of the Mediterranean diet are significant, however its effects appear to be even more marked when a daily 30-gram serve of nuts is incorporated. The Mediterranean diet plus nuts group in the PREDIMED study displayed some additional long-term health benefits that were not observed in the olive oil or control groups.  

 Cardiovascular disease   

• Reduced levels of tissue factor pathway inhibitor, which inhibits thrombin, a substance that plays a role in the blood clotting process   

• Delayed progression of internal carotid intima-media thickness and plaque   

• Lower mean plasma glucose levels   

• Lower systolic and diastolic blood pressure   

• Significantly lower LDL (bad) cholesterol   

• Healthier LDL:HDL cholesterol ratio   

• Increased fibre intake  

• Increased polyunsaturated (good) fat intake  

Weight management   

• Improved Body Mass Index (BMI)   

• Improved waist circumference   

• Inverse association between nut consumption and obesity and central obesity   

• A lifetime habit of eating 30 grams of nuts 3+ times per week resulted in a 39% reduction in total mortality in an older Mediterranean population at high risk of CVD 

Diabetes   

 • Inverse relationship with diabetes: eating 3+ serves of nuts per week significantly lowers the risk of diabetes, compared to eating one or fewer serves per week   

Metabolic syndrome   

• Inverse relationship with metabolic syndrome: eating 3+ serves of nuts per week lowers the risk of developing metabolic syndrome, compared to eating one or fewer serves per week   

• Potential to reverse metabolic syndrome, in particular, reduced waist circumference Brain health   

• Significant association with improved levels of brain-derived neurotrophic factor (BDNF) in people suffering from depression. BDNF is a protein thought to be connected with depression. Higher levels are associated with better brain health.  

It’s never too late to change! 

When you consider that all these positive health outcomes were found in a study of people aged 55-80, it’s clear that it’s never too late to change our dietary habits to improve our health. So if you’re looking to make some positive changes to the way you eat, why not start by grabbing a handful of your favourite nuts for your next snack, and make improvements from there. Further details of the PREDIMED study and a full list of references can be found here.

This blog was updated 31 May 2017